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<v Speaker 1>All right, let's continue with our next module. Here.

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<v Speaker 2>We're gonna be talking about reactants, impedance, resonance, and active

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<v Speaker 2>components in this section, So let's talk about reactance. Reactance

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<v Speaker 2>is the resistance to the flow of current caused by

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<v Speaker 2>capacitance or inductance. It's denoted by the letter X, and

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<v Speaker 2>it's measured in homes like resistance capacitive reactants, which is

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<v Speaker 2>the opposite, which is the opposition to AC current flow

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<v Speaker 2>from the store energy in the capacitor is denoted by XC.

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<v Speaker 2>Capacitors behave differently with AC and DC.

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<v Speaker 1>Current with DC.

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<v Speaker 2>When voltage is instantly applied, capacitor looks like a short circuit.

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<v Speaker 2>After charging, it looks like an open circuit. This is

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<v Speaker 2>how it blocks DC signals. However, AC behavior depends upon

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<v Speaker 2>voltage frequency. Here you can see some graft. If you

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<v Speaker 2>have a capacitor, as soon as you apply voltage, it's

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<v Speaker 2>a short circuit and the voltage rises up to the

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<v Speaker 2>applied voltage over a specific set of specific amount of time,

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<v Speaker 2>and when you remove the voltage from the capacitor then

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<v Speaker 2>it slowly decays down to zero volts.

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<v Speaker 1>Again.

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<v Speaker 2>So when a circuit contained a capacitors first, energize, the

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<v Speaker 2>vultage across the capacitor is zero.

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<v Speaker 1>And the current's very large.

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<v Speaker 2>As time passes, the voltage across the capacitor increases and

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<v Speaker 2>the current drops toward towards zero. As a frequency of

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<v Speaker 2>the applied signal increases, the reactive.

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<v Speaker 1>Capacitance decreases, and vice versa.

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<v Speaker 2>What is the reactance of a one nano farreed capacitor

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<v Speaker 2>at two megahertz? Well, first we have to convert megaherts

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<v Speaker 2>the hertz and nanofage to ferreds. Two megaherts is two

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<v Speaker 2>times tens of the six herts. One nano fareed is

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<v Speaker 2>one times ten to the minus nine fair ads, So

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<v Speaker 2>the equation of capacitive reactants is one over two pi

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<v Speaker 2>the frequency times capasit So in this case it's equel

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<v Speaker 2>one over two times three point four times two times

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<v Speaker 2>ten to the six times one times ten to the

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<v Speaker 2>minus nine, which comes out to be seventy nine point

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<v Speaker 2>six ohms. So the capacity of reactants of a one

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<v Speaker 2>nanofarreed capacitor at two megahertz is seventy nine points six omes.

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<v Speaker 2>Inductive reactants is the opposition to ac current flow from

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<v Speaker 2>the stored energy in an inductor and is denoted by XL.

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<v Speaker 2>Behavior with frequency is described as below. XL is equal

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<v Speaker 2>to two pi times the frequency times the inductance in henrys.

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<v Speaker 2>As a frequency F is of the applied signal increases, XL.

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<v Speaker 1>Increases, and vice versa.

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<v Speaker 2>When a circuit containing introductor is first energized, the initial

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<v Speaker 2>current is zero and the full applied voltage appears across

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<v Speaker 2>the inductor. As time passes, the voltage drops down towards

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<v Speaker 2>zero has shown in this figure, and the current increases

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<v Speaker 2>is shown in B. What is the reactance of a

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<v Speaker 2>ten Microhindr inductor at five megahertz? First we convert microhenries

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<v Speaker 2>to Henri's and megahertz to hertz. That way everything has

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<v Speaker 2>the same base units. So five megahurts is five times

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<v Speaker 2>ten to the six hertz. Ten microhendris is one times

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<v Speaker 2>ten to the minus five henris, and from our equation,

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<v Speaker 2>the reactive the inductive reactants is two pi times of

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<v Speaker 2>frequency times l, So in this case it's two times

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<v Speaker 2>three point one four times five times in the six

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<v Speaker 2>times one times ten to the minus five or about

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<v Speaker 2>three hundred and fourteen omes. So the reactance of a

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<v Speaker 2>ten Microhindry inductor at five megahertz is three hundred and

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<v Speaker 2>fourteen homes. Parasitic inductance is unwanted. Parasitic inductance is an

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<v Speaker 2>unwanded characteristic that results from the component's physical construction. The

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<v Speaker 2>coils in a wire wound resistor, for example, create pair

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<v Speaker 2>parasitic in inductance. Wire leads of components at inductance that

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<v Speaker 2>we of parasitic inductance, and in inductors, each pair of

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<v Speaker 2>turns creates parasitic capacitance in series, with the inductance often

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<v Speaker 2>significant enough to disrupt the circuit's operation or affect tuning

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<v Speaker 2>in the radios. Some capacitors made of thin foils.

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<v Speaker 1>Are rolled up.

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<v Speaker 2>The rolled up construction creates parasitic inductance. It's very high

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<v Speaker 2>in electrolytic capacity. This limbits are used to relatively low frequencies.

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<v Speaker 2>Tanelum and ceramic capacitors have little parasitic inductance and can

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<v Speaker 2>be used up to microwave frequencies. What is reactants is

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<v Speaker 2>that the opposition of the flow of direct current caused

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<v Speaker 2>by resistance. Nope, it's the opposition of the flow of

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<v Speaker 2>ultimating current caused by capacitive or inductance.

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<v Speaker 1>What reactance is.

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<v Speaker 2>Which of the following causes opposition to the flow of

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<v Speaker 2>alternating current in an inductor.

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<v Speaker 1>It's going to be reactance.

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<v Speaker 2>Which of the following causes opposition to the flow of

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<v Speaker 2>alternating incurring in a capacitor and its reactance?

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<v Speaker 1>How much?

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<v Speaker 2>How does an A D an AC? How does an

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<v Speaker 2>inductor react to AC As a frequency of the applied

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<v Speaker 2>AC increases, the reactants decreases or does it increase? All right,

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<v Speaker 2>so the frequency increases as the as the applied AC increases,

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<v Speaker 2>which is D as the frequency. As a frequency goes.

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<v Speaker 1>Up, inductance goes up the reactants.

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<v Speaker 2>How does a capacitor react to AC, Well, it's the opposite,

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<v Speaker 2>So as the frequency goes up the reactants and decreases

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<v Speaker 2>in a in a capacitor, So it'd be a what

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<v Speaker 2>unit is used to measure reactants.

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<v Speaker 1>Be the ome?

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<v Speaker 2>What should wire round resistors? Why should wire round resistors

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<v Speaker 2>not be used in RAF circuits? Let's see, Because let's see,

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<v Speaker 2>the resist induction can make circuit performs unpredictables. The terms

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<v Speaker 2>of dis capacitance would two the circuit. So I think

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<v Speaker 2>it's going to be D. Nope, the resistance inductions could

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<v Speaker 2>make the performance unpredictable because there's parasitic because there's parasitic

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<v Speaker 2>reactants in there.

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<v Speaker 1>Okay.

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<v Speaker 2>Impedance is the opposition to current flow in an AC

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<v Speaker 2>circuit caused by resistance, reactants, or any combination of the two.

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<v Speaker 2>It's also impedances is denoted by the letter Z. It's

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<v Speaker 2>measured in ohms. So remember, impedance is the opposition to

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<v Speaker 2>current flow in an AC circuit caused by resistance, reactive,

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<v Speaker 2>or any combination of the two.

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<v Speaker 1>Okay, Like resistance, it's.

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<v Speaker 2>The ratio of voltage to current. It's the inverse of

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<v Speaker 2>impedance is admittance. So resonance indicates a match between the

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<v Speaker 2>frequency at which a circuit or intenda naturally responds to

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<v Speaker 2>the frequency of an applied signal. Resonance occurs when capacitance reactives.

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<v Speaker 2>Reactance is equal to inductive reactants. So when those two

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<v Speaker 2>are equal, then you're gonna have resonance. In a resonance

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<v Speaker 2>series circuit, reactance of L and C cancel, making it

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<v Speaker 2>sh making a short circuit, leaving only the resistance.

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<v Speaker 1>As a circuit's impedance.

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<v Speaker 2>Read Resonance is used in filters and tuned circuits to

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<v Speaker 2>pass or reject specific frequencies, so resonance is a very

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<v Speaker 2>important piece of amateur radio used a lot in our

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<v Speaker 2>RF circuits. In a resonance series circuit, the reactance of

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<v Speaker 2>L and the reactance of C cancel, making this making

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<v Speaker 2>a short circuit. This leaves only the resistance as a

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<v Speaker 2>circuit's impedance. Self resonance resonance can occur when a component's

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<v Speaker 2>expected reactance equals the reactance of its parasitic reactants, called

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<v Speaker 2>self resonance.

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<v Speaker 1>Results.

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<v Speaker 2>Then self resonance results in a component that appears to

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<v Speaker 2>be short or open circuit at the self resonant frequency.

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<v Speaker 2>Above this frequency, the components reactive the reactants switches tight,

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<v Speaker 2>making an inductor capacitive and a capacitor inductive, so that's

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<v Speaker 2>above the self resonance frequency of the device. Impedance transformer

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<v Speaker 2>is a transformer that can change the combination of voltage

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<v Speaker 2>and current while transferring energy. The transformer also changes impedance

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<v Speaker 2>between the primary and the secondary circuits by changing the

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<v Speaker 2>ratio of voltage and current between the primary and secondary circuits.

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<v Speaker 2>The turns ratio controls the transformation in the same ways

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<v Speaker 2>as the ratio of gear teeth and a mechanical transmission.

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<v Speaker 2>So impedance transformers. This is real similar to the volted

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<v Speaker 2>transformer we just saw, except we've got impedance. Now, what

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<v Speaker 2>is the primary impedance of a two hundred ERME load

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<v Speaker 2>is connected to the secondary of a transformer with the

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<v Speaker 2>five to one secondary to primary turns ratio. Well, using

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<v Speaker 2>our equation filling in our numbers, it's two hundred divided

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<v Speaker 2>by one over five, which about eight omes. So if

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<v Speaker 2>I've got a two hundred zero load, if I got

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<v Speaker 2>two hundred oz impedance on one side of a transformer

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<v Speaker 2>and a five to one winding ratio, it will transform

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<v Speaker 2>that impedance to eight to eight excuse me, to eight omes. Okay,

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<v Speaker 2>what's the turns ration? What turns ratio is required to

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<v Speaker 2>change a five hundred, six hundred impedance into a fifty impedance. Well,

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<v Speaker 2>it's going to be the square root of the impedance

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<v Speaker 2>ratio six hundred divided by fifty square root of twelve

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<v Speaker 2>three point four to six. So if I had a

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<v Speaker 2>six hundred oerme impedance on one side of my transformer, I.

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<v Speaker 1>Needed to get to fifty homes.

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<v Speaker 2>I'd have to have a turns ratio of three point

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<v Speaker 2>four to six in my windings.

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<v Speaker 1>Note that the impedance to be changed.

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<v Speaker 2>In this case, six hundred homes can be connected to

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<v Speaker 2>the primary or secondary, but turns ratios are always stated

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<v Speaker 2>with the larger number first three point four six to one,

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<v Speaker 2>not one point three point four to six, because remember

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<v Speaker 2>a transformer, you can hook up both directions, but it's

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<v Speaker 2>always stated with the turns ratio of the primary.

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<v Speaker 1>First and energy sources.

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<v Speaker 2>Ability to deliver power to a load is limited by

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<v Speaker 2>its internal impedance. Amateur transmitting equipment is designed so that

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<v Speaker 2>the internal impedance of its output circuits is fifty homes.

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<v Speaker 2>If the difference between the antenna's system impedance and the

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<v Speaker 2>transmitter output impedance is greater enough, the transmitter may reduce

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<v Speaker 2>output power to avoid damage. So what you need to

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<v Speaker 2>do is put in an impedance matching circuit. This is

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<v Speaker 2>the case where you've got an antenna that's other than

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<v Speaker 2>fifty homes. Most impedance matching circuits are LC circuits and

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<v Speaker 2>duct and capacitors. UH They are called PIE or T

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<v Speaker 2>networks based on how they're configured. On the left is

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<v Speaker 2>the PIE network. You notice it's an inductor with two capacitors,

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<v Speaker 2>and a T network is two capacitors with one inductor.

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<v Speaker 2>Impedis matching can also be performed by special links and

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<v Speaker 2>connections of a transmission line. Okay, what happens when an

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<v Speaker 2>inductive and capacitive reactants are equal in a serious circuit?

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<v Speaker 2>This means emped's are very low pieces equal to the

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<v Speaker 2>I think it's going to be c The resonance causes

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<v Speaker 2>impedans to be very low, so the two cancel each

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<v Speaker 2>other out and you only have the resistance value left

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<v Speaker 2>the real resistance. What is the term of the inverse

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<v Speaker 2>of impedance admittance? What is impedance?

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<v Speaker 1>It's the It's.

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<v Speaker 2>The the ratio voltage to current number similar to equals.

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<v Speaker 1>I are.

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<v Speaker 2>Which of the following devices can we used for impedance

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<v Speaker 2>matching at radio frequencies? A transformer, a pig network, link

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<v Speaker 2>of transmission line, all the choices?

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<v Speaker 1>I think it's all these.

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<v Speaker 2>Remember we talked about a transformer, a pied network, a

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<v Speaker 2>transmission line. All these can be used to transformer match

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<v Speaker 2>What letters used to represent reactants X? What occurs in

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<v Speaker 2>an LC circuit at resonance current voltage or equal?

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<v Speaker 1>Nope? A circuit Nope.

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<v Speaker 2>The inductance, reactants, and capacitance cancel each other. D What

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<v Speaker 2>transformer turns ratio matches and antenna's six hundred one feed

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<v Speaker 2>point to impedance to a fifty zero coaxial cable.

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<v Speaker 1>It's about a three and a half to one a M.

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<v Speaker 2>What happens when an inductor is operated above its self

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<v Speaker 2>resonant frequency? UH, it becomes capacitive. Remember inductor above itself

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<v Speaker 2>resonant inductor becomes capacitive and a capacitor becomes inductive above

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<v Speaker 2>its self resonant frequency. What is one reason to use

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<v Speaker 2>an impedance transformer at a transmitter output?

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<v Speaker 1>Uh?

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<v Speaker 2>Present desired reduced to minimize to present the desired impedance

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<v Speaker 2>with the transformer feed line b.

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<v Speaker 1>KAY.

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<v Speaker 2>Talk about some semiconductor components. The most common active components

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<v Speaker 2>are made of semiconductors. Most are made of silicon or germanium.

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<v Speaker 2>Electrical properties can be controlled by addition of small amounts

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<v Speaker 2>of dopants or impurities such as indium and phosphorus. If

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<v Speaker 2>the impurity creates it an excess of electrons, the result

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<v Speaker 2>is an N type material, and the opposite deficiency of

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<v Speaker 2>electrons is P type So those are the two type

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<v Speaker 2>of semiconductor materials that we commonly use. Where NP type,

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<v Speaker 2>N type and P type are in contact. Where those

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<v Speaker 2>two come together, it's called a P N junction. Okay,

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<v Speaker 2>here's a diode semiconductor junction. That's a diode uses a

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<v Speaker 2>P P type material and an N type P has

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<v Speaker 2>excess electrons, in has deficient electrons. When those two come

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<v Speaker 2>together and a boundary is called the junction. And let's

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<v Speaker 2>see current flows when positive voltage is applied from the

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<v Speaker 2>P type to N type material, that's called Ford bias.

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<v Speaker 2>And if I hope the power up backwards is not

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<v Speaker 2>going to flow, so current flows when positive voltage is

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<v Speaker 2>applied from P.

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<v Speaker 1>To end ford bias.

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<v Speaker 2>Voltage applied in the opposite direction is called reverse bias.

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<v Speaker 2>It pulls electrons away from the junction, so no current

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<v Speaker 2>can flow across the junction. Voltage required to force electrons

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<v Speaker 2>across the through the junction is called forward voltage or

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<v Speaker 2>junction threshold voltage. For silicon diodes, the Ford voltage is

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<v Speaker 2>zero point seven volts. For germanium diodes it's point three volts.

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<v Speaker 2>There's different types of diodes. There's light emitting diodes called

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<v Speaker 2>LED laser diodes, avalanche zine or shot key.

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<v Speaker 1>There's a bunch and they have different they're all diodes.

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<v Speaker 2>They have different applications and different properties and can be

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<v Speaker 2>used for different types of things in your electrical circuit.

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<v Speaker 2>Diodes are rated by their peak inverse voltage. That's the

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<v Speaker 2>maximum voltage they can stand before breaking down Negatively, there's

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<v Speaker 2>specified with their forward voltage how much voltage it takes

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<v Speaker 2>to turn the voltage on to get ford current flow

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<v Speaker 2>exceeding a diodes writing will destroy the diodes internal structure

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<v Speaker 2>junction capacitants when reverse biased layers of the P and

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<v Speaker 2>N type material act like capacitors. The larger the c

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<v Speaker 2>the longer it takes to switch it to conducting forward current.

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<v Speaker 2>So if you want something that switches fast like a

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<v Speaker 2>transmit received dide, or you want something that's got lower

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<v Speaker 2>capacitans in the junction, if we add a third layer

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<v Speaker 2>of semiconductor material, you get a transistor. This is a

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<v Speaker 2>bipolar transistor. You notice you've got two P type materials

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<v Speaker 2>with an end between them. That's called the PNP transistor.

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<v Speaker 2>And if you have N type materials on the end

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<v Speaker 2>with the P type in the middle. It's called it

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<v Speaker 2>N P in transistor. These are the two base six

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<v Speaker 2>types of bipolar transistors. They've got to have power on

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<v Speaker 2>them to function. There's three electrodes. There's the collector, the base,

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<v Speaker 2>and the emitter, and they're controlled by the current flow

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<v Speaker 2>between the It's controlled by the current flow between the

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<v Speaker 2>base and the emitter. Very little base emitter current is

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<v Speaker 2>required for collector emitter current to flow. The control of

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<v Speaker 2>large current by smaller current is called amplification. The ratio

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<v Speaker 2>of collector emitter current to base emitter current is called

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<v Speaker 2>current gain. Current gain for DC signals is abbreviated with beta.

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<v Speaker 1>Current gain for.

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<v Speaker 2>AC signals is HFE. Field effector transistors has three electrodes,

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<v Speaker 2>a diode, a source and a gate. Instead of controlling drain,

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<v Speaker 2>instead of controlling drained source current with gate source current,

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<v Speaker 2>the voltage between gate and the source is used instead

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<v Speaker 2>of current gain, FET has transconductance, which is a ratio

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<v Speaker 2>of source drain current through gate voltage. So bipolar transistor

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<v Speaker 2>uses current to control flow. Field effect transistor used voltage.

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<v Speaker 2>MOSS FETs, which stands for metal oxide semiconductor FETs use

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<v Speaker 2>oxide layer to insulate the gate. So when you look

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<v Speaker 2>at the figure on the right, here here's an inf channel.

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<v Speaker 2>It's got a P material N and a P in

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<v Speaker 2>the middle, and then the opposite is a P channel

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<v Speaker 2>FAT which has an end channel substrate.

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<v Speaker 1>FETs are very sensitive.

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<v Speaker 2>They require only small amounts of voltage to control the

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<v Speaker 2>source drain current. High amplification makes the ideal for use

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<v Speaker 2>of switches both voltage and current. With enough voltage, transistors

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<v Speaker 2>can be driven into saturation, where further increases an input

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<v Speaker 2>results of no change in output. High enough input signals

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<v Speaker 2>can reduce outputs current to to zero.

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<v Speaker 1>Which is called cut off.

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<v Speaker 2>Saturation and cut off conditions are are excellent representations of

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<v Speaker 2>digital on off signals and logical circuits.

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<v Speaker 1>So what is the proximate junction threshold.

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<v Speaker 2>Of a germanium diode and it's about point three volts

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<v Speaker 2>and the forward threshold voltage of a silicon junction diode

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<v Speaker 2>is point seven volts. And what are the operating points

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<v Speaker 2>of a bipolar transistor used as a switch that would

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<v Speaker 2>be saturation and cut off? Which of the following describes

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<v Speaker 2>a mossvat construction. Let's see the gate is rented by

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<v Speaker 2>the gates are separated from the channel by a thin

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<v Speaker 2>insulating layer.

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<v Speaker 1>KAY, tell me about vacuum tubes.

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<v Speaker 2>Vacuum tubes have at least three electrodes called elements.

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<v Speaker 1>The three basic parts are.

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<v Speaker 2>Sm the source of electrons, the electrode to collect the electrons,

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<v Speaker 2>and intervening electrodes that control the flow or the travel

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<v Speaker 2>from source to collector. So you've got a source of

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<v Speaker 2>place to collect them, and something to control them. The

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<v Speaker 2>three parts of a vacuum tube. Compared to transistors, they're

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<v Speaker 2>most like the fet they operate. Tubes operate at high

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<v Speaker 2>hazardous voltage two to three thousand volts, so always exercise

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<v Speaker 2>costume and working around vacuum tubes. A filament or heater

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<v Speaker 2>heats the cathode it's causing it to emit electrons inside

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<v Speaker 2>the tube. The cathode is the source of electrons, and

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<v Speaker 2>the control grid, which is the grid closest to the cathode,

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<v Speaker 2>is used to regulate the electron travel between cathode and plate.

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<v Speaker 2>The screen grid, which is the electrode that reduces grid

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<v Speaker 2>to plate capacitance suppressure grid prevents electrons from traveling from

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<v Speaker 2>plate to control or screen grid, and the plate collects electrons,

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<v Speaker 2>and that's called plate current. Which element of a vacuum

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<v Speaker 2>tube regulates the flow of electrons between cathode and plate.

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<v Speaker 2>That'd be the control grid. What is the primary purpose

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<v Speaker 2>of a screen grid in a vacuum tube to reduce

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<v Speaker 2>grid to plate capacitance. Now we'll talk a little about

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<v Speaker 2>analog ice circuits, and ICE is an electronic circuit formed

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<v Speaker 2>on a small piece of semiconducting material, performing the same

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<v Speaker 2>function as a larger circuit.

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<v Speaker 1>Made from discrete chips.

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<v Speaker 2>Uh ICs can operate over a continuous range of voltages

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<v Speaker 2>and currents. They're used for amplification, filtering, measurement, voltage regulation,

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<v Speaker 2>and power control. Most common analog icees operational amplifier and

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<v Speaker 2>linear voltage regulators op amps are used for DC and

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<v Speaker 2>audio circuits. They're inexpensive source of gain. Linear voltage regulators

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<v Speaker 2>maintain power supply output at constant voltages over a wide

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<v Speaker 2>range of currents. So ICs are used in just about

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<v Speaker 2>everything that we have today. All these modern radios we

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<v Speaker 2>have have lots of chips in them.

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<v Speaker 1>The popular seven symbol.

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<v Speaker 2>Here's what a AMP symbol looks like, shown in a package.

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<v Speaker 2>What's called a dual inline package or a DIP and

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<v Speaker 2>it's got connections one through eight. You can see the

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<v Speaker 2>schematic how it's pinned out, and then there's a two

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<v Speaker 2>twenty package which is real common for a voltage regulator.

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<v Speaker 1>That's what they look like.

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<v Speaker 2>Digital integrated circuits operate with discrete values of voltage and

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<v Speaker 2>current representing the binary numbers between values of zero in

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<v Speaker 2>one that is representing on and off. Digital ICs are

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<v Speaker 2>used for performing computations or controlling functions. The most popular

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<v Speaker 2>logic family is C MOSS, which stands for a complementary

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<v Speaker 2>metal oxide semiconductor technology known for high speed and low

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<v Speaker 2>power consumption. And here's the chart that shows the logic

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<v Speaker 2>family characteristics of the different types of families TTL, SE

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<v Speaker 2>MOSS and SEA MOSS.

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<v Speaker 1>The four thousand.

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<v Speaker 2>Series you can see the operating frequency ranges, power consumption,

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<v Speaker 2>and the supply voltage. The basic building block of digital

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<v Speaker 2>circuits are called gates that perform inversion that is, changing

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<v Speaker 2>one to zero or vice versa in the ore and functions.

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<v Speaker 2>The most common gates in use are the inverter nand

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<v Speaker 2>and nore For more complex functions such as microprocesses and

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<v Speaker 2>signal processors. They're constructed from combinations of these functions. So

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<v Speaker 2>all the inverter nand and nore are the basic building

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<v Speaker 2>blocks for all the big microprocessors that we have. That's

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<v Speaker 2>just a whole bunch of combinations of those gates. Circuits

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<v Speaker 2>that use gates to combine binary inputs to generate a

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<v Speaker 2>binary output or combination of binary outputs are called it's

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<v Speaker 2>called combinational logic. And here's some schematics for some basic

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<v Speaker 2>digital functions with the logical equations and truth tables that

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<v Speaker 2>describe their operations. So if you look a logic symbol

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<v Speaker 2>for a gate A and B and C, so c

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<v Speaker 2>the output if the input, if the inputs are the same,

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<v Speaker 2>if the inputs if any input zero, the output zero.

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<v Speaker 2>If the inputs are there are ones and the output one,

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<v Speaker 2>so they both and they both have to be the.

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<v Speaker 1>Same to have an output of one. An or gate.

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<v Speaker 2>Takes the two inputs and or or it ors them together.

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<v Speaker 2>So if I have a any input has a one

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<v Speaker 2>on it, the output's.

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<v Speaker 1>Going to have a one A two.

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<v Speaker 2>Input and gate. Either A and B are off, the

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<v Speaker 2>gate is off. Both have to be on for the

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<v Speaker 2>gate to be on. For a two input or gate,

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<v Speaker 2>either A or B are on, the gate is on.

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<v Speaker 2>Both have to be off for the gate to be off.

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<v Speaker 2>Can you think of examples where this might be used.

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<v Speaker 2>Maybe a gumball machine you need to insert a coin

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<v Speaker 2>and press a button to dispense. So you've got to

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<v Speaker 2>do this and that then something happens, or an intrusive

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<v Speaker 2>detection the alarm sounds for intrusion, or the front door

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<v Speaker 2>or bedroom window, so either have this window, either this

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<v Speaker 2>alarm or this alarm.

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<v Speaker 1>That's an an or function.

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<v Speaker 2>Schematic symbols for the basic digital functions, with the logic

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<v Speaker 2>equations and truth tables already described in their operations. So

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<v Speaker 2>here's a here's here's an inverter. Whatever the input is,

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<v Speaker 2>it converts it to the opposite, So a zero becomes

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<v Speaker 2>a one, one becomes a zero.

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<v Speaker 1>Uh.

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<v Speaker 2>And the two input nand gate. It's the the two inputs.

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<v Speaker 2>It's it's the invert of the hand gate. So if

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<v Speaker 2>I want the output to be a one of the

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<v Speaker 2>any of the inputs have to be Any of the

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<v Speaker 2>one inputs have to be zero. If I want the

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<v Speaker 2>output to be a zero, both inputs have to be

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<v Speaker 2>a one. So here's a no or gate and against.

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<v Speaker 2>It's the opposite of the or gate. It takes the

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<v Speaker 2>output of the or of the or gate and and

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<v Speaker 2>inverts it. So if I have any input that's a one,

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<v Speaker 2>the outputs a zero. If both inputs are zero, the

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<v Speaker 2>outputs a one, and here's a flip flop. The flip

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<v Speaker 2>flop is used to store.

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<v Speaker 1>The next condition.

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<v Speaker 2>So if I have an input, if my inputs are

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<v Speaker 2>one in one and I get a clock, the outputs

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00:27:08.799 --> 00:27:11.519
<v Speaker 2>one in one. If the inputs one in one goes

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<v Speaker 2>to the next state, output is going to be a zero.

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<v Speaker 2>So sequential logic circuits combine binary signals in a way

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<v Speaker 2>that depends on time and on the sequence of inputs

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<v Speaker 2>to the circuits. Basic building blocks for sequential logic is

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<v Speaker 2>the flip flop. It responds to a clock signal that

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<v Speaker 2>causes its output to change based on input.

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<v Speaker 1>The two outputs q and.

427
00:27:37.880 --> 00:27:41.160
<v Speaker 2>Qbar are always in opposite states, connecting the flip flops

428
00:27:41.200 --> 00:27:45.480
<v Speaker 2>together to one flip flops output feeds the next one's input,

429
00:27:45.640 --> 00:27:48.519
<v Speaker 2>which creates a two important circuits called a counter and

430
00:27:48.559 --> 00:27:52.960
<v Speaker 2>a shift register. In counter logic, the outputs of the

431
00:27:53.039 --> 00:27:55.359
<v Speaker 2>chain of flip flops make up a binary number of

432
00:27:55.720 --> 00:27:58.240
<v Speaker 2>or state representing the number of clock signals that have

433
00:27:58.319 --> 00:28:01.799
<v Speaker 2>been occurred. Each flip flop stores one bit of the

434
00:28:01.880 --> 00:28:07.200
<v Speaker 2>total count. Highest number of count counter can represent. The

435
00:28:07.279 --> 00:28:10.480
<v Speaker 2>highest number a counter can represent is two to the end,

436
00:28:10.519 --> 00:28:12.319
<v Speaker 2>where end is a number of flip flops that make

437
00:28:12.400 --> 00:28:16.359
<v Speaker 2>up the counter. A three bit counter which has three

438
00:28:16.359 --> 00:28:19.720
<v Speaker 2>flip flops can count two to the three or eight states.

439
00:28:20.400 --> 00:28:23.279
<v Speaker 2>A four bit can count sixteen states, a five bit

440
00:28:23.440 --> 00:28:24.759
<v Speaker 2>thirty two states, et cetera.

441
00:28:26.240 --> 00:28:27.240
<v Speaker 1>Shift registers.

442
00:28:27.799 --> 00:28:30.640
<v Speaker 2>If you connect the array of a flip flop slightly differently,

443
00:28:30.880 --> 00:28:34.559
<v Speaker 2>results in a shift register. Shift register stores a sequence

444
00:28:34.559 --> 00:28:37.319
<v Speaker 2>of ones and zeros from its input as the flip

445
00:28:37.319 --> 00:28:41.839
<v Speaker 2>flop outputs. Each clock signal causes the value of the

446
00:28:41.839 --> 00:28:44.200
<v Speaker 2>shift register's input to pass or shift to the next

447
00:28:44.240 --> 00:28:49.079
<v Speaker 2>flip flop in the string. Some shift register circuits can

448
00:28:49.119 --> 00:28:52.880
<v Speaker 2>be configured to shift up and down or forward and backward,

449
00:28:53.880 --> 00:28:59.000
<v Speaker 2>a simple form of a digital memory r F circuits.

450
00:29:00.000 --> 00:29:02.440
<v Speaker 2>They're designed to function as either like low level high

451
00:29:02.440 --> 00:29:06.119
<v Speaker 2>gain amplifiers, mixers, modulators, demodulators, filters.

452
00:29:07.119 --> 00:29:08.559
<v Speaker 1>They greatly reduce the number.

453
00:29:08.400 --> 00:29:12.240
<v Speaker 2>Of discrete devices required to build a radio circuit, so

454
00:29:12.279 --> 00:29:14.519
<v Speaker 2>you can get an RF integrated circuit that has a

455
00:29:14.559 --> 00:29:16.160
<v Speaker 2>lot of these components already.

456
00:29:15.920 --> 00:29:16.640
<v Speaker 1>Built into it.

457
00:29:17.400 --> 00:29:22.599
<v Speaker 2>Monolithic microwave integrated circuits MMC are special types of RFICs

458
00:29:22.599 --> 00:29:26.119
<v Speaker 2>that work through microwave frequencies and they perform several functions.

459
00:29:26.640 --> 00:29:29.960
<v Speaker 2>They enable construction of low cost cell phones, GPS receivers,

460
00:29:30.480 --> 00:29:33.559
<v Speaker 2>and those types of things. So what is meant by

461
00:29:33.599 --> 00:29:40.640
<v Speaker 2>the term MMIC. It is a monolithic microwave integrated circuit.

462
00:29:41.960 --> 00:29:44.119
<v Speaker 2>Which of the following is an advantage of C MOSS

463
00:29:44.160 --> 00:29:50.359
<v Speaker 2>integrated circuits compared to TTL circuits low power consumption. What

464
00:29:50.519 --> 00:29:55.799
<v Speaker 2>kind of device is an integrated circuit operational amplifier? It's

465
00:29:55.839 --> 00:30:00.400
<v Speaker 2>an analog device. Which of the following describes the function

466
00:30:00.440 --> 00:30:06.240
<v Speaker 2>of a two input and gate. Okay, output is high

467
00:30:06.359 --> 00:30:08.160
<v Speaker 2>only when both inputs are high.

468
00:30:08.240 --> 00:30:08.839
<v Speaker 1>That would be b.

469
00:30:09.720 --> 00:30:12.680
<v Speaker 2>How many states does a three bit binary counter have?

470
00:30:13.359 --> 00:30:14.519
<v Speaker 2>So remember you take.

471
00:30:16.039 --> 00:30:16.880
<v Speaker 1>Two to the end.

472
00:30:17.079 --> 00:30:19.960
<v Speaker 2>If it's three, it's two to the end, so that

473
00:30:20.000 --> 00:30:22.079
<v Speaker 2>would have to be eight.

474
00:30:23.400 --> 00:30:24.880
<v Speaker 1>What's a shift register.

475
00:30:26.160 --> 00:30:29.519
<v Speaker 2>Clocked array of circuits that passes that data and steps

476
00:30:29.519 --> 00:30:37.079
<v Speaker 2>along the array. It's a Okay, microprocessors and microcontroller I

477
00:30:37.119 --> 00:30:40.880
<v Speaker 2>see that are capable of performing millions of computing instructions

478
00:30:40.880 --> 00:30:46.359
<v Speaker 2>per second. That's what a microprocessor is programs must be

479
00:30:46.359 --> 00:30:50.559
<v Speaker 2>stored in memory devices so the microprocessor can read the instructions.

480
00:30:51.319 --> 00:30:55.119
<v Speaker 2>There's volatile memory, which loses the memory when the power

481
00:30:55.160 --> 00:30:59.960
<v Speaker 2>is removed. There's non volatile memory, which stores the data permanently.

482
00:30:59.559 --> 00:31:00.519
<v Speaker 1>Even with the out power.

483
00:31:01.359 --> 00:31:04.039
<v Speaker 2>And there's random access memory, which can be read and

484
00:31:04.119 --> 00:31:07.440
<v Speaker 2>right from or written to. Then there's read only memory,

485
00:31:07.440 --> 00:31:12.519
<v Speaker 2>which stores data permanently cannot be changed. Data interfaces. Microprocessors

486
00:31:12.519 --> 00:31:18.079
<v Speaker 2>communicate through data interfaces. There's two types, serial and parallel interfaces.

487
00:31:18.680 --> 00:31:21.880
<v Speaker 2>Serial transfers one bit at a time in each each direction.

488
00:31:23.240 --> 00:31:30.279
<v Speaker 2>Parallel transforms multiple bits in each for each operation. One

489
00:31:30.359 --> 00:31:35.240
<v Speaker 2>byte is typically eight bits and one bit.

490
00:31:36.519 --> 00:31:36.920
<v Speaker 1>There you go.

491
00:31:39.240 --> 00:31:43.359
<v Speaker 2>Amateur equipment uses two types of devices to present information visually,

492
00:31:43.799 --> 00:31:50.400
<v Speaker 2>indicators to prevent to present information visually, either indicators or displays.

493
00:31:51.279 --> 00:31:54.759
<v Speaker 2>Indicators present on off information, usually by the presence of

494
00:31:54.799 --> 00:31:59.160
<v Speaker 2>the absence of light or color. Common indicators include incandescent

495
00:31:59.200 --> 00:32:03.519
<v Speaker 2>light bulbs and light emitting diodes. For indicators displays, they

496
00:32:03.559 --> 00:32:08.920
<v Speaker 2>present textra graphics, information, and visual film. LEDs have large

497
00:32:09.079 --> 00:32:12.759
<v Speaker 2>and largely replaced incandescent light bulbs and amateur equipment. They

498
00:32:12.839 --> 00:32:15.319
<v Speaker 2>last longer, can be turned on off more quickly and

499
00:32:15.480 --> 00:32:18.720
<v Speaker 2>use less power and generate less heat. They're also available

500
00:32:18.759 --> 00:32:21.759
<v Speaker 2>in many colors, and they're made from special types of

501
00:32:21.759 --> 00:32:25.519
<v Speaker 2>semiconnecting material that light that emit light when the p

502
00:32:25.640 --> 00:32:28.960
<v Speaker 2>in junction is forward bias, so LED, like the term says,

503
00:32:29.039 --> 00:32:33.480
<v Speaker 2>is a diode. Liquid crystal display, probably the most common

504
00:32:33.519 --> 00:32:37.960
<v Speaker 2>type of display, is created by sandwiching liquid crystal between

505
00:32:38.799 --> 00:32:43.640
<v Speaker 2>between glass panels. A pattern of electrodes is printed in

506
00:32:43.680 --> 00:32:46.160
<v Speaker 2>a thin film on the front panel, with a single

507
00:32:46.279 --> 00:32:49.839
<v Speaker 2>electrode covering the rear panel. Boltage is applied to the

508
00:32:49.880 --> 00:32:53.559
<v Speaker 2>front panel, causing the crystal to twist and a configuration

509
00:32:53.640 --> 00:32:58.359
<v Speaker 2>that blocks light. LCDs require ambient or backlighting the light

510
00:32:58.440 --> 00:33:01.839
<v Speaker 2>source behind the crystal layer since layer crystal layer. Since

511
00:33:01.880 --> 00:33:05.359
<v Speaker 2>the crystal layer does not regenerate light on its own.

512
00:33:06.240 --> 00:33:09.480
<v Speaker 2>Compared to LCDs, LEDs have higher contrasts where there is

513
00:33:09.519 --> 00:33:13.160
<v Speaker 2>a high ambient light on a sunny day. How's an

514
00:33:13.240 --> 00:33:18.240
<v Speaker 2>LED bias when emitting light? It's forward biased. We're gonna

515
00:33:18.240 --> 00:33:24.640
<v Speaker 2>be talking about practical circuits, basic test equipment, all right, Yeah,

516
00:33:25.119 --> 00:33:29.680
<v Speaker 2>amateur radio electronic equipment requires DC power, so a power

517
00:33:29.680 --> 00:33:31.880
<v Speaker 2>supply is required to turn to make it run from

518
00:33:32.039 --> 00:33:35.960
<v Speaker 2>household AC power. Most amateur radio equipment uses DC power

519
00:33:36.079 --> 00:33:39.359
<v Speaker 2>thirteen point eight volts, which is chosen to be compatible

520
00:33:39.400 --> 00:33:44.799
<v Speaker 2>with vehicle power systems. Power supplies have three basic parts,

521
00:33:45.640 --> 00:33:51.720
<v Speaker 2>the input transformer, erectifire and filter regular output circuit. There's

522
00:33:51.759 --> 00:33:55.160
<v Speaker 2>two types of rectifier circuits here. A halfway rectifier converts

523
00:33:55.200 --> 00:33:59.000
<v Speaker 2>only one half of the input waveform. This creates a

524
00:33:59.039 --> 00:34:02.039
<v Speaker 2>series of pulses of current and the load of the

525
00:34:02.079 --> 00:34:06.039
<v Speaker 2>same frequency as the input voltage. A full wave rectifier

526
00:34:06.119 --> 00:34:08.480
<v Speaker 2>converts the entire input wave from.

527
00:34:08.280 --> 00:34:09.480
<v Speaker 1>Three hundred and sixty degrees.

528
00:34:09.920 --> 00:34:13.000
<v Speaker 2>This is this is really two half wave rectifiers operating

529
00:34:13.599 --> 00:34:17.079
<v Speaker 2>alt on the ultimate half cycles. It requires that the

530
00:34:17.119 --> 00:34:19.599
<v Speaker 2>transform to the center tap to provide a pattern a

531
00:34:19.679 --> 00:34:23.480
<v Speaker 2>return path for current following the load. So if you

532
00:34:23.519 --> 00:34:25.159
<v Speaker 2>take a look at the picture here on the right,

533
00:34:25.239 --> 00:34:28.480
<v Speaker 2>so halfway rectifier, the output of a halfway so you

534
00:34:28.559 --> 00:34:32.360
<v Speaker 2>got AC coming in and the dialde blocks half of

535
00:34:31.440 --> 00:34:35.280
<v Speaker 2>the negative cycles, so you get an output that looks

536
00:34:35.320 --> 00:34:40.000
<v Speaker 2>like this. On a full wave rectifire, you block half

537
00:34:40.000 --> 00:34:42.519
<v Speaker 2>of it come in one direction and half it go

538
00:34:42.599 --> 00:34:45.239
<v Speaker 2>in the other direction, and so you get you get

539
00:34:45.280 --> 00:34:48.960
<v Speaker 2>all you get all the you get the negative sineway

540
00:34:49.119 --> 00:34:52.360
<v Speaker 2>shows up on the top. It conducts in the opposite direction.

541
00:34:53.119 --> 00:34:56.360
<v Speaker 2>I get three piece through three voltages here versus six

542
00:34:56.519 --> 00:35:03.119
<v Speaker 2>on on this end, so I'll have less ripple. The

543
00:35:03.119 --> 00:35:05.480
<v Speaker 2>advantage of a full wave rectifiers that the output is

544
00:35:05.519 --> 00:35:08.280
<v Speaker 2>produced during the entire three sixty degrees of the wave cycle.

545
00:35:08.280 --> 00:35:11.920
<v Speaker 2>It's more efficient. The output from full wave rectifiers in

546
00:35:11.960 --> 00:35:15.920
<v Speaker 2>a series of pulses that twice the frequency of the

547
00:35:15.920 --> 00:35:18.760
<v Speaker 2>input voltage. So if my input is so my input

548
00:35:18.800 --> 00:35:21.800
<v Speaker 2>voltage at sixty hertz, full wave rectifier is going to

549
00:35:21.880 --> 00:35:28.320
<v Speaker 2>have one hundred and twenty hertz frequency range. Here's a

550
00:35:28.440 --> 00:35:34.519
<v Speaker 2>full wave rectifier. You can see this circuit adds two

551
00:35:34.519 --> 00:35:37.800
<v Speaker 2>more to adds to two more dials for total of four,

552
00:35:38.400 --> 00:35:41.760
<v Speaker 2>but eliminates the need for the center tap winding. Another

553
00:35:41.800 --> 00:35:44.840
<v Speaker 2>type of full wave rectifier. This circuit adds two diodes

554
00:35:44.880 --> 00:35:47.679
<v Speaker 2>total of four, but eliminates the need for center tap winding.

555
00:35:49.119 --> 00:35:51.280
<v Speaker 2>Rectifier output pulses.

556
00:35:51.960 --> 00:35:54.000
<v Speaker 1>Are used well.

557
00:35:54.039 --> 00:35:57.599
<v Speaker 2>These full wave rectifiers are used in power supply filter circuits.

558
00:35:59.599 --> 00:36:02.320
<v Speaker 2>Rectify our output pulses of DC current don't provide a

559
00:36:02.360 --> 00:36:06.400
<v Speaker 2>stable voltage for direct use by electronics. The variation in

560
00:36:06.559 --> 00:36:11.280
<v Speaker 2>output vultures is called ripple pulses must be smooth out

561
00:36:11.320 --> 00:36:16.000
<v Speaker 2>by a filter network, which consists of capacitors or capacitors

562
00:36:16.000 --> 00:36:20.440
<v Speaker 2>and inductors. The most common way to reduce ripple is

563
00:36:20.480 --> 00:36:26.840
<v Speaker 2>a filter capacitor or capacitor input filter. Older high voltage

564
00:36:26.840 --> 00:36:30.360
<v Speaker 2>circuits may use what's called choke conductors, so power supply

565
00:36:30.519 --> 00:36:34.519
<v Speaker 2>safety fuses is the primary. Fuses in the primary are

566
00:36:34.599 --> 00:36:37.800
<v Speaker 2>used to protect against short circuits or excessive current loads.

567
00:36:39.159 --> 00:36:43.400
<v Speaker 2>Bleeder resistors discharge stored energy when the supply is turned off.

568
00:36:43.440 --> 00:36:46.239
<v Speaker 2>So when you turn off a power supplies, sometimes you

569
00:36:46.280 --> 00:36:47.440
<v Speaker 2>have like a light one you can see the light

570
00:36:47.519 --> 00:36:50.599
<v Speaker 2>stay on and it finally goes off. That's the bleeder

571
00:36:50.639 --> 00:36:54.679
<v Speaker 2>resistor in there feeding off the voltage. Because a lot

572
00:36:54.719 --> 00:36:57.800
<v Speaker 2>of these power supplies have a large capacitor on them

573
00:36:57.840 --> 00:37:00.480
<v Speaker 2>to get rid of that ripple, and if you don't

574
00:37:00.480 --> 00:37:02.880
<v Speaker 2>bleed off that charge, it will stay there for a while.

575
00:37:02.960 --> 00:37:07.599
<v Speaker 2>So that's called a bleeder resistor does that. Working on

576
00:37:07.639 --> 00:37:09.719
<v Speaker 2>power supplies, you need to wait for the bleeder resistor

577
00:37:09.760 --> 00:37:13.719
<v Speaker 2>to discharge or eat the energy, even if it's unplugged.

578
00:37:15.159 --> 00:37:15.480
<v Speaker 1>Okay.

579
00:37:15.599 --> 00:37:20.320
<v Speaker 2>Switch mode power supplies, the AC input is first rectified

580
00:37:20.320 --> 00:37:25.719
<v Speaker 2>and filtered a transistor switched a transistor. Switched pulses at

581
00:37:25.800 --> 00:37:29.440
<v Speaker 2>high frequency usually twenty kill hers in that range or more,

582
00:37:29.920 --> 00:37:33.679
<v Speaker 2>transfer energy to the filter capacitor, which smoothes out the ripple.

583
00:37:34.679 --> 00:37:37.639
<v Speaker 2>High frequency enables power supply to quickly change to current

584
00:37:37.679 --> 00:37:41.119
<v Speaker 2>demands and means that small lightweight inductor to capacitors can

585
00:37:41.119 --> 00:37:45.719
<v Speaker 2>be used to filter the output. Here's a block diagram

586
00:37:45.920 --> 00:37:50.639
<v Speaker 2>of a switching power supply AC's first input to the rectify.

587
00:37:51.800 --> 00:37:56.920
<v Speaker 2>Its first ac input is first rectified and filtered transistor.

588
00:37:56.920 --> 00:38:01.880
<v Speaker 2>Switch then supplies current pulses to a small doctor or transformer,

589
00:38:02.320 --> 00:38:06.760
<v Speaker 2>which transfers the energy into another filter capacitor that smooths

590
00:38:07.599 --> 00:38:10.639
<v Speaker 2>the pulses for a steady output voltage. The high frequency

591
00:38:10.679 --> 00:38:14.679
<v Speaker 2>of the pulses means that the supply can react quickly

592
00:38:14.719 --> 00:38:18.280
<v Speaker 2>to changing current demands. The high frequency also means that

593
00:38:18.360 --> 00:38:21.119
<v Speaker 2>small lightweight inductors and capassitors can be used to smooth

594
00:38:21.119 --> 00:38:23.960
<v Speaker 2>out the pulses and the filter and filter the output.

595
00:38:24.639 --> 00:38:28.159
<v Speaker 2>So what is the function of a power supply bleader resistor? Well,

596
00:38:28.199 --> 00:38:32.440
<v Speaker 2>you remember it's it's there to remove the To remove

597
00:38:32.480 --> 00:38:38.559
<v Speaker 2>the voltage, it discharges the capacitor the filter capacitors when

598
00:38:38.599 --> 00:38:42.440
<v Speaker 2>the power is removed, which of the following components are

599
00:38:42.519 --> 00:38:48.159
<v Speaker 2>used in power supply filter network diodes, transformers and transducers,

600
00:38:48.199 --> 00:38:49.280
<v Speaker 2>capassitors and inductors.

601
00:38:49.360 --> 00:38:50.119
<v Speaker 1>It have to be c.

602
00:38:52.760 --> 00:38:56.360
<v Speaker 2>Which type of rectifier circuit uses two diodes and a

603
00:38:56.440 --> 00:39:05.599
<v Speaker 2>center tap transformer via the full wave rectifier? What is

604
00:39:05.679 --> 00:39:08.599
<v Speaker 2>characteristic of a half wave rectifier and a power supply

605
00:39:10.800 --> 00:39:14.920
<v Speaker 2>only when doubt is required that recal frequency is twice

606
00:39:14.920 --> 00:39:19.079
<v Speaker 2>out of the current can be drawn A only has

607
00:39:19.119 --> 00:39:23.440
<v Speaker 2>one diete half wave rectifier. What portion of the AC

608
00:39:23.599 --> 00:39:27.760
<v Speaker 2>signal is converted to DC by a half wave rectifier

609
00:39:30.880 --> 00:39:36.480
<v Speaker 2>one hundred and eighty degrees? What portion of AC cycle

610
00:39:36.559 --> 00:39:38.880
<v Speaker 2>is converted to d C by a full wave rectifier

611
00:39:39.719 --> 00:39:43.000
<v Speaker 2>three hundred and sixty degrees. It's doing the full wave.

612
00:39:45.920 --> 00:39:48.760
<v Speaker 2>What is the output waveform of an unfiltered full wave

613
00:39:48.800 --> 00:39:54.880
<v Speaker 2>rectifier connected to a resistive load series of DC pulses

614
00:39:54.880 --> 00:39:58.239
<v Speaker 2>at twice the frequency of the AC output When you

615
00:39:58.280 --> 00:40:01.119
<v Speaker 2>re memory of the full wave rectifier, You've got both

616
00:40:01.159 --> 00:40:03.679
<v Speaker 2>the high end the lows, so it's twice the frequency

617
00:40:03.719 --> 00:40:07.480
<v Speaker 2>coming out. Which of the following is characteristic of a

618
00:40:07.519 --> 00:40:10.559
<v Speaker 2>switch mode power supply as compared to a linear power supply.

619
00:40:14.000 --> 00:40:16.960
<v Speaker 2>High I put that the viewers circuits. High frequency. It's

620
00:40:16.960 --> 00:40:22.920
<v Speaker 2>going to be higher frequency operation, the use of smaller components. Okay,

621
00:40:22.960 --> 00:40:26.480
<v Speaker 2>now we're going to talk about batteries and chargers. There's

622
00:40:26.519 --> 00:40:32.079
<v Speaker 2>two types of batteries, primary and secondary. Primary usually disposable,

623
00:40:32.159 --> 00:40:37.760
<v Speaker 2>discarded after discharging. Battery chemistry is usually carbon link, alkaline

624
00:40:37.800 --> 00:40:42.719
<v Speaker 2>or silver nickel. Referably to secondary batteries for emergency operation.

625
00:40:42.840 --> 00:40:49.000
<v Speaker 2>Because AC power may not be available for charging the secondary,

626
00:40:49.519 --> 00:40:54.760
<v Speaker 2>they can be recharged reused many times. Battery chemistries include nickel, cadmium, nickel,

627
00:40:54.760 --> 00:41:01.760
<v Speaker 2>metal hydride, litimion, lead acid. Here's a charge that shows

628
00:41:02.280 --> 00:41:06.480
<v Speaker 2>some of the different battery types and their power ratings.

629
00:41:07.079 --> 00:41:12.800
<v Speaker 2>Just some interesting information about them. Hey, storage batteries. You know,

630
00:41:13.599 --> 00:41:17.719
<v Speaker 2>Larger secondary batteries use for emergency or portable power to

631
00:41:17.800 --> 00:41:22.199
<v Speaker 2>replace power supplies operating from AC power. Usually the battery

632
00:41:22.280 --> 00:41:26.360
<v Speaker 2>chemistry of these is lead acid or liquid electrolyte gel electrolyte.

633
00:41:28.280 --> 00:41:30.960
<v Speaker 2>They're rated of twelve volte batteries, but are actually thirteen

634
00:41:30.960 --> 00:41:35.159
<v Speaker 2>point eight bolts. Lead acid batteries can produce useful power

635
00:41:35.199 --> 00:41:39.800
<v Speaker 2>down to about ten point five bolts. Discharging below minimum

636
00:41:39.880 --> 00:41:44.719
<v Speaker 2>voltage will reduce the battery life limiting amount of current

637
00:41:44.880 --> 00:41:47.760
<v Speaker 2>drawing keeps the battery cool and extends its life, so

638
00:41:48.760 --> 00:41:52.239
<v Speaker 2>you know be conscious of that. Some battery types nickel

639
00:41:52.440 --> 00:41:57.079
<v Speaker 2>cadm nickel cadmiums are designed to have low internal resistance

640
00:41:57.199 --> 00:42:02.199
<v Speaker 2>to supply high discharge currents. So based on your application

641
00:42:02.280 --> 00:42:04.679
<v Speaker 2>of your battery, you may be a certain type of

642
00:42:04.719 --> 00:42:08.039
<v Speaker 2>battery that's for the to be right for your application.

643
00:42:09.079 --> 00:42:12.559
<v Speaker 2>Batteries slowly lose charge when they're not in use. That's

644
00:42:12.599 --> 00:42:18.519
<v Speaker 2>called self discharge. You can be minimized by keeping the

645
00:42:18.519 --> 00:42:22.599
<v Speaker 2>battery cool and dry, but avoid freezing. Expanding water can

646
00:42:22.599 --> 00:42:27.639
<v Speaker 2>crack the case or damaging electrodes. Some alternate power sources

647
00:42:27.679 --> 00:42:33.320
<v Speaker 2>a solar power photo voltaic conversion of sunlight to electricity.

648
00:42:33.519 --> 00:42:36.360
<v Speaker 2>Solar panels are cells are actually a special type of

649
00:42:36.400 --> 00:42:41.519
<v Speaker 2>diode silicon p injunctions. When solar cells, photons are absorbed

650
00:42:41.519 --> 00:42:44.320
<v Speaker 2>by electrons, giving them enough energy to travel across the

651
00:42:44.320 --> 00:42:48.559
<v Speaker 2>p in junction and create DC current flow. The ford

652
00:42:48.599 --> 00:42:50.960
<v Speaker 2>voltage created about half of a volt is called the

653
00:42:51.039 --> 00:42:58.679
<v Speaker 2>open circuit voltage. When solar power systems require substantial energy storage.

654
00:42:59.079 --> 00:43:01.400
<v Speaker 2>When connecting is so solar panel to a lithium ion

655
00:43:01.400 --> 00:43:05.159
<v Speaker 2>phosphate battery use a charge controller to avoid overcharging the battery.

656
00:43:05.960 --> 00:43:10.079
<v Speaker 2>You want to make sure you use the proper the

657
00:43:10.119 --> 00:43:14.159
<v Speaker 2>proper the proper controllers. You need something between your solar

658
00:43:14.159 --> 00:43:19.159
<v Speaker 2>panel and your batteries as a solar panel charger. Solar

659
00:43:19.159 --> 00:43:21.719
<v Speaker 2>connections are made through a series connected diode to prevent

660
00:43:21.840 --> 00:43:25.119
<v Speaker 2>damage from discharging back through the panel during periods of

661
00:43:25.159 --> 00:43:29.960
<v Speaker 2>low illumination produce voltage. Solar panels and solar cells are

662
00:43:29.960 --> 00:43:33.039
<v Speaker 2>made of silicon pian junctions are exposed to sunlight and

663
00:43:33.159 --> 00:43:39.079
<v Speaker 2>a range in a series parallel configuration. In the configuration

664
00:43:39.719 --> 00:43:42.280
<v Speaker 2>in what configuration are the individual cells and a solar

665
00:43:42.280 --> 00:43:47.320
<v Speaker 2>panel connected together. They're connected in a series parallel combination.

666
00:43:49.199 --> 00:43:52.480
<v Speaker 2>What is the approximate open circuit voltage from a fully

667
00:43:52.599 --> 00:44:00.559
<v Speaker 2>illuminated silicon photovotaic sell It's zero point five volts. Why

668
00:44:00.599 --> 00:44:03.400
<v Speaker 2>should a series diode be connected between a solar panel

669
00:44:03.599 --> 00:44:06.320
<v Speaker 2>and a storage panel that is being charged by the

670
00:44:06.360 --> 00:44:09.360
<v Speaker 2>panel to prevent discharge of the battery through the panel

671
00:44:09.440 --> 00:44:14.920
<v Speaker 2>during times of low or no illumination. What precaution should

672
00:44:14.920 --> 00:44:17.519
<v Speaker 2>be taken when connecting a solar panel to a lithium

673
00:44:17.639 --> 00:44:23.400
<v Speaker 2>iron phosphate battery. A solar panel must have a charge controller. Again,

674
00:44:23.440 --> 00:44:26.760
<v Speaker 2>You've got to have something in between your solar panel

675
00:44:26.800 --> 00:44:33.239
<v Speaker 2>and your battery. What is the minimum allowable discharge voltage

676
00:44:33.280 --> 00:44:36.840
<v Speaker 2>for maximum life of a standard TWEBAL lead acid battery,

677
00:44:37.639 --> 00:44:40.199
<v Speaker 2>and that's ten point five volts? Do you get below

678
00:44:40.239 --> 00:44:42.719
<v Speaker 2>ten point five volts your batteries? I can produce any

679
00:44:42.760 --> 00:44:46.880
<v Speaker 2>more power on a lead acid What is advantage of

680
00:44:47.119 --> 00:44:52.320
<v Speaker 2>batteries with low internal resistance that have a higher discharge current.

681
00:44:54.119 --> 00:44:59.079
<v Speaker 2>That's the main thing. Let's talk about connectors. There's some

682
00:44:59.079 --> 00:45:03.159
<v Speaker 2>connection technology. Pins are contacts that extend out of the

683
00:45:03.159 --> 00:45:08.719
<v Speaker 2>connector body, male sockets or hollow recess contacts. We call

684
00:45:08.760 --> 00:45:15.440
<v Speaker 2>those the female. Keyed connectors specially shaped bodies or inserts

685
00:45:15.440 --> 00:45:20.159
<v Speaker 2>to prevent damage from connecting m in correctly. So usually

686
00:45:20.159 --> 00:45:22.920
<v Speaker 2>connectors are keyed so you can't you know, so they

687
00:45:22.960 --> 00:45:28.760
<v Speaker 2>can't physically connect them wrong. Plugs are connectors installed on

688
00:45:28.760 --> 00:45:32.440
<v Speaker 2>the ends of cables. Jacks or receptacles are connectors installed

689
00:45:32.440 --> 00:45:37.159
<v Speaker 2>on equipment. Adapters make connections between two different types of connectors.

690
00:45:37.159 --> 00:45:42.559
<v Speaker 2>Styles and splitters divide signals between two connectors. There's a

691
00:45:42.599 --> 00:45:46.599
<v Speaker 2>picture of some common connectors used in amateur radio. On

692
00:45:46.679 --> 00:45:51.280
<v Speaker 2>the power connector side, mulex connectors, the Anderson power pole

693
00:45:51.360 --> 00:45:57.840
<v Speaker 2>that antijacks, binding posts, terminal scripts, you can terminals that

694
00:45:57.880 --> 00:46:00.000
<v Speaker 2>are crimped to the ends of wires. There's all kinds

695
00:45:59.960 --> 00:46:04.400
<v Speaker 2>of different types of tempt UH wire terminals that that

696
00:46:04.400 --> 00:46:08.760
<v Speaker 2>that that that can be used and powerpole connectors have

697
00:46:08.840 --> 00:46:14.199
<v Speaker 2>become the standard used by areas. Anderson connectors are sexless.

698
00:46:14.199 --> 00:46:18.960
<v Speaker 2>By standardizing on a single UH style, equipment can be

699
00:46:19.000 --> 00:46:21.480
<v Speaker 2>easily shared and replaced. And we do use that in

700
00:46:21.519 --> 00:46:23.519
<v Speaker 2>all of our area stuff here, all my stuff that

701
00:46:23.559 --> 00:46:26.920
<v Speaker 2>I use in my home shack is all converted over

702
00:46:26.960 --> 00:46:31.960
<v Speaker 2>to the Anderson powerpool type. Makes a lot easier to

703
00:46:32.119 --> 00:46:38.599
<v Speaker 2>connect everything together. UH. Note that these are crimp terminals,

704
00:46:39.039 --> 00:46:42.400
<v Speaker 2>so you need special crimping tools to attach the wires

705
00:46:42.400 --> 00:46:45.840
<v Speaker 2>to the lugs. Avoid using fliers. Use the right tools

706
00:46:45.880 --> 00:46:50.840
<v Speaker 2>for the job. That's pretty important. So audio connections, they

707
00:46:50.840 --> 00:46:53.280
<v Speaker 2>come in quarter inch and eight inch are the most popular,

708
00:46:54.119 --> 00:46:57.440
<v Speaker 2>and they have a contact at the end of the

709
00:46:57.480 --> 00:47:00.159
<v Speaker 2>plug which is called the tip, and the connect there

710
00:47:00.199 --> 00:47:04.039
<v Speaker 2>at the base is called the sleeve. UH. The third

711
00:47:04.119 --> 00:47:06.519
<v Speaker 2>contact and some of them is in the middle and

712
00:47:06.519 --> 00:47:12.000
<v Speaker 2>it's called the ring. Bunnyl plug jack's also called r

713
00:47:12.119 --> 00:47:15.039
<v Speaker 2>c as are used for audio, video and lower level

714
00:47:15.199 --> 00:47:18.239
<v Speaker 2>r F signals and control signals. Use the lot for

715
00:47:18.280 --> 00:47:23.039
<v Speaker 2>between your amplifier for your push to talk lines. Here's

716
00:47:23.159 --> 00:47:28.480
<v Speaker 2>here's some pictures of some RF connectors. These are a

717
00:47:28.519 --> 00:47:32.440
<v Speaker 2>lot of these are coaxial type connectors. Each type is

718
00:47:33.239 --> 00:47:35.920
<v Speaker 2>especially especially made to carry r F signals and preserve

719
00:47:36.039 --> 00:47:40.719
<v Speaker 2>the shielding of the coax Cable adapters are available, you know,

720
00:47:40.880 --> 00:47:45.360
<v Speaker 2>to connect one style to another. These are the most

721
00:47:45.400 --> 00:47:49.880
<v Speaker 2>common ones. For US, we use the h U h F,

722
00:47:50.039 --> 00:47:52.679
<v Speaker 2>the p L two fifty nine and SO two thirty nine.

723
00:47:52.719 --> 00:47:55.480
<v Speaker 2>The N types B n c's. Those two are probably

724
00:47:55.480 --> 00:48:00.639
<v Speaker 2>the most common. Radio signals require special connectors to be used.

725
00:48:00.639 --> 00:48:05.519
<v Speaker 2>Are frequencies. Connectors may have about the same impedance as

726
00:48:05.559 --> 00:48:07.480
<v Speaker 2>the feed line, or some of the signal will be

727
00:48:07.519 --> 00:48:12.000
<v Speaker 2>reflected by the connector. Most common connector is the UHF family.

728
00:48:12.320 --> 00:48:16.719
<v Speaker 2>UHF here does not mean ultra high frequency. UHF connectors

729
00:48:16.719 --> 00:48:19.679
<v Speaker 2>are typically used up to one hundred and fifty megaherts

730
00:48:19.719 --> 00:48:24.159
<v Speaker 2>and can handle legal transmit power at HF. UHF connector

731
00:48:24.239 --> 00:48:29.679
<v Speaker 2>drawbacks do have lack of weather proofing, inconsistent performance above

732
00:48:29.679 --> 00:48:33.639
<v Speaker 2>one hundred and fifty megahertz, limited power handling, type in

733
00:48:33.880 --> 00:48:37.800
<v Speaker 2>series our connectors address some of those drawbacks. They can

734
00:48:37.840 --> 00:48:41.360
<v Speaker 2>be used up to ten gigahertz. BNC connectors are used

735
00:48:41.360 --> 00:48:44.920
<v Speaker 2>for low power common in handhelds, for and for antennas

736
00:48:46.039 --> 00:48:52.159
<v Speaker 2>upper limit for low SWR operations for gigahertz. SMA connectors

737
00:48:52.199 --> 00:48:55.760
<v Speaker 2>are small threaded connector designed for miniature coacts related to

738
00:48:55.800 --> 00:49:01.840
<v Speaker 2>eighteen gigahertz, also used for hand for handhelds. Those are

739
00:49:01.840 --> 00:49:04.079
<v Speaker 2>the those are the most common ones that you see.

740
00:49:04.400 --> 00:49:08.000
<v Speaker 2>A lot of your hpees have SMAs and uh Some

741
00:49:08.119 --> 00:49:11.199
<v Speaker 2>are male, some are females. Some are reverse mail to.

742
00:49:12.000 --> 00:49:16.119
<v Speaker 2>When you're buying antennas and connectors that that mate that

743
00:49:16.159 --> 00:49:17.840
<v Speaker 2>mate with them, you need to double check what you've

744
00:49:17.840 --> 00:49:22.920
<v Speaker 2>got on data connector. Digital data's exchanged between radios and

745
00:49:22.960 --> 00:49:26.840
<v Speaker 2>computer equipment UH now more than it used to in

746
00:49:26.920 --> 00:49:29.159
<v Speaker 2>amateur radio. We have a lot more data connections on

747
00:49:29.199 --> 00:49:32.559
<v Speaker 2>our radios. Uh D type connectors are used for R

748
00:49:32.639 --> 00:49:36.840
<v Speaker 2>S two thirty two or comport interfaces. The model number

749
00:49:36.880 --> 00:49:39.400
<v Speaker 2>of a D type connector specifiers for a number of

750
00:49:39.440 --> 00:49:43.400
<v Speaker 2>circuits and a P or s depending on pins or sockets.

751
00:49:44.119 --> 00:49:47.320
<v Speaker 2>U dB nine connector has nine pins and those are

752
00:49:47.440 --> 00:49:50.519
<v Speaker 2>typical use for the comports on PC's not as much

753
00:49:50.559 --> 00:49:55.480
<v Speaker 2>so anymore. Okay, what's a typical upper frequency uh for

754
00:49:55.599 --> 00:49:58.519
<v Speaker 2>lowest of your operation on a fifty OME B and

755
00:49:58.599 --> 00:49:59.320
<v Speaker 2>C connector?

756
00:49:59.559 --> 00:50:00.519
<v Speaker 1>You remember where it was?

757
00:50:00.760 --> 00:50:02.519
<v Speaker 2>I think it was four gigaherts?

758
00:50:02.760 --> 00:50:03.400
<v Speaker 1>See yep.

759
00:50:05.000 --> 00:50:09.199
<v Speaker 2>Which of the following describes a type end connector moisture

760
00:50:09.239 --> 00:50:12.639
<v Speaker 2>resistance up to ten gigaherts? I think that's right. The

761
00:50:13.079 --> 00:50:17.960
<v Speaker 2>end connector has got some environmental features that makes it

762
00:50:18.000 --> 00:50:23.159
<v Speaker 2>good for outside use. What's an SMA connector? I know

763
00:50:23.559 --> 00:50:27.039
<v Speaker 2>it's a small threaded connector or suitable for signals up

764
00:50:27.079 --> 00:50:31.519
<v Speaker 2>to several gigaherts. And those are real comment like I said,

765
00:50:31.519 --> 00:50:33.480
<v Speaker 2>on hds, because they're small.

766
00:50:33.320 --> 00:50:33.920
<v Speaker 1>More than anything.

767
00:50:35.960 --> 00:50:38.239
<v Speaker 2>Which of these types connectors is commonly used for low

768
00:50:38.280 --> 00:50:44.039
<v Speaker 2>frequency or DC signal connections to a transceiver. That would

769
00:50:44.039 --> 00:50:47.880
<v Speaker 2>be the RCA phono type. All right, we're going to

770
00:50:47.920 --> 00:50:51.760
<v Speaker 2>talk about some basic test equipment now. Analog and digital

771
00:50:51.800 --> 00:50:56.559
<v Speaker 2>meters a volt oh meter, VOM or a multimeter is

772
00:50:56.559 --> 00:50:59.800
<v Speaker 2>the simplest and very versatile piece of test equipment. There's

773
00:50:59.800 --> 00:51:05.280
<v Speaker 2>two types. Analog and digital. Volt meter can measure voltage,

774
00:51:05.639 --> 00:51:10.840
<v Speaker 2>current resistance, can check continuity, check diodes, test transistors Some

775
00:51:10.880 --> 00:51:15.480
<v Speaker 2>of them have frequency counters on them, some measure capacitance inductance,

776
00:51:15.920 --> 00:51:17.880
<v Speaker 2>and a lot of them have an interface to a

777
00:51:17.880 --> 00:51:21.639
<v Speaker 2>PC to record the readings. Digital multimeters offer great precision,

778
00:51:21.960 --> 00:51:26.360
<v Speaker 2>greater precision than analog meters to find a heat or

779
00:51:26.400 --> 00:51:29.559
<v Speaker 2>a minimum value, for example, when they're just in a

780
00:51:29.679 --> 00:51:35.760
<v Speaker 2>tune in a circuit. Experienced hands often prefer analog meters

781
00:51:36.000 --> 00:51:38.719
<v Speaker 2>easier to just watch the analog meter move in a

782
00:51:38.800 --> 00:51:41.760
<v Speaker 2>display than on a digital meter. You can watch the

783
00:51:41.800 --> 00:51:44.559
<v Speaker 2>needle find its thaying. On an analog meter, it's thinking

784
00:51:45.480 --> 00:51:48.280
<v Speaker 2>and settling down. It just depends on what you're trying

785
00:51:48.320 --> 00:51:48.719
<v Speaker 2>to measure.

786
00:51:49.400 --> 00:51:49.679
<v Speaker 1>Meters.

787
00:51:50.440 --> 00:51:52.960
<v Speaker 2>Meters should affect the circuit being measured in the smallest

788
00:51:52.960 --> 00:51:56.320
<v Speaker 2>degree possible. With measuring voltage, meters should have a high

789
00:51:56.360 --> 00:51:59.159
<v Speaker 2>input impedance so that it places the minimum load on

790
00:51:59.159 --> 00:52:02.239
<v Speaker 2>the circuit we're going to talk about. The next is

791
00:52:02.280 --> 00:52:07.039
<v Speaker 2>the assilloscope. Sill scope provides a visual display of voltage

792
00:52:07.119 --> 00:52:11.639
<v Speaker 2>versus against time. The display is updated thousands or million

793
00:52:11.679 --> 00:52:14.440
<v Speaker 2>times per second to give a real time view. The

794
00:52:14.480 --> 00:52:18.280
<v Speaker 2>signal's characteristics allows for the measurement of fast changing wave

795
00:52:18.360 --> 00:52:22.400
<v Speaker 2>forms that can't be measured by other meters. Signals are

796
00:52:22.400 --> 00:52:25.599
<v Speaker 2>connected to the scope through horizontal and vertical channel amplifiers.

797
00:52:25.880 --> 00:52:30.239
<v Speaker 2>Amplifier gain is variable to adjust vertical sensitivity of the

798
00:52:30.239 --> 00:52:32.960
<v Speaker 2>scopes display.

799
00:52:34.119 --> 00:52:34.519
<v Speaker 1>Monitoring.

800
00:52:34.519 --> 00:52:37.840
<v Speaker 2>The silloscopes are sometimes used to monitor the transmitted signals

801
00:52:37.880 --> 00:52:41.119
<v Speaker 2>by connecting the attenuated RF output of the transmitter to

802
00:52:41.159 --> 00:52:46.760
<v Speaker 2>the vertical channel of the scope. This assists in adjusting keywaveforms,

803
00:52:46.840 --> 00:52:51.760
<v Speaker 2>microphone gain, and speech processing. When adjusting keying waveforms such

804
00:52:51.760 --> 00:52:54.679
<v Speaker 2>as a CW transmitter, the operator can see on the

805
00:52:54.719 --> 00:52:57.599
<v Speaker 2>scope display the effects of the any adjustments or conditions

806
00:52:57.599 --> 00:53:00.440
<v Speaker 2>that might cause distortion or key clicks of the transit

807
00:53:00.480 --> 00:53:02.000
<v Speaker 2>of the retransmitted signal.

808
00:53:04.199 --> 00:53:05.119
<v Speaker 1>One thing about.

809
00:53:04.920 --> 00:53:09.280
<v Speaker 2>Scopes, Some of these new radios have an audioscope on

810
00:53:09.360 --> 00:53:11.079
<v Speaker 2>them and you can actually see your wave form of

811
00:53:11.159 --> 00:53:13.119
<v Speaker 2>your voice and those kinds of things. Those are kind

812
00:53:13.119 --> 00:53:18.599
<v Speaker 2>of deep, okay. Impedance and resonant measurements. An intented analyzer

813
00:53:18.639 --> 00:53:23.239
<v Speaker 2>contains a CW signal generator, frequency counter, SWR bridge, and

814
00:53:23.280 --> 00:53:27.599
<v Speaker 2>an impedance meter all in one package. They connect to

815
00:53:27.639 --> 00:53:30.800
<v Speaker 2>the antenna feed line to measure standing wave ratio without

816
00:53:30.880 --> 00:53:34.920
<v Speaker 2>having to transmit a signal at high power. They measure

817
00:53:34.920 --> 00:53:40.239
<v Speaker 2>feed line velocity factor electrical length, characteristic impediance, and other parameters.

818
00:53:40.559 --> 00:53:43.639
<v Speaker 2>They're very handy item they have around the shack. Because

819
00:53:43.679 --> 00:53:46.679
<v Speaker 2>they use small signals. Accuracy can be affected by strong

820
00:53:46.719 --> 00:53:49.320
<v Speaker 2>signals from nearby transmitters, so you have to be careful.

821
00:53:49.400 --> 00:53:54.360
<v Speaker 2>So somebody's transmitting near by, they can maybe affect your reading,

822
00:53:54.400 --> 00:53:57.880
<v Speaker 2>but it doesn't happen much. But an antenna analyz there's

823
00:53:57.920 --> 00:54:00.280
<v Speaker 2>a nice piece of equipment to have around the shack.

824
00:54:02.320 --> 00:54:05.920
<v Speaker 2>Field strength and r F power meters UH, they're useful. UH.

825
00:54:06.360 --> 00:54:11.079
<v Speaker 2>Other useful tests that include antenna efficiency and radiation pattern UH.

826
00:54:11.519 --> 00:54:15.920
<v Speaker 2>Those can be measured with the field strength meter. Field

827
00:54:15.920 --> 00:54:19.119
<v Speaker 2>strength meters are often used for comparing relative levels of

828
00:54:19.239 --> 00:54:24.000
<v Speaker 2>r F output during antenna and transmitter adjustments. Radiation pattern

829
00:54:24.039 --> 00:54:27.599
<v Speaker 2>is measured by placing field strength meter in one location

830
00:54:27.719 --> 00:54:30.360
<v Speaker 2>in rotating the antenna, or the meter can be carried

831
00:54:30.360 --> 00:54:34.159
<v Speaker 2>at different locations that determine the radiation pattern of a

832
00:54:34.280 --> 00:54:37.760
<v Speaker 2>fixed antenna. They're useful that there would be a very

833
00:54:37.840 --> 00:54:43.920
<v Speaker 2>useful piece of equipment. I have had one. I've done

834
00:54:43.960 --> 00:54:47.119
<v Speaker 2>some antenna measurements. Antenna measurements are very difficult to do though,

835
00:54:49.519 --> 00:54:52.920
<v Speaker 2>so directional watt meters U can be used to measure

836
00:54:52.960 --> 00:54:57.599
<v Speaker 2>both forward and reflected power. Standing wave ratio can be

837
00:54:57.639 --> 00:55:03.079
<v Speaker 2>calculated from forward and reflected power measurements. The SWR formulas

838
00:55:03.119 --> 00:55:07.760
<v Speaker 2>right down there. It's the ratio of the power reflected

839
00:55:07.880 --> 00:55:11.440
<v Speaker 2>versus powered forward And what type of test equipment contains

840
00:55:11.480 --> 00:55:17.280
<v Speaker 2>horgonal and vertical channel amplifiers. That would be the silloscope.

841
00:55:19.239 --> 00:55:21.159
<v Speaker 2>Which of the following is an advantage of the sell

842
00:55:21.199 --> 00:55:24.679
<v Speaker 2>scope versus a digital volte meter? You can see complex

843
00:55:24.760 --> 00:55:30.519
<v Speaker 2>waveforms on a scope. Which of the following is the

844
00:55:30.519 --> 00:55:33.880
<v Speaker 2>best instrument to use when checking the key ray form

845
00:55:33.880 --> 00:55:35.320
<v Speaker 2>of a CW transmitter?

846
00:55:37.519 --> 00:55:38.880
<v Speaker 1>That would be a.

847
00:55:40.920 --> 00:55:46.519
<v Speaker 2>Silloscope. What signal source is connected to the vertical input

848
00:55:46.639 --> 00:55:49.360
<v Speaker 2>of a asilloscope when checking the RF envelope pattern of

849
00:55:49.400 --> 00:55:53.199
<v Speaker 2>a transmitted signal? That would be the attenuating r F

850
00:55:53.280 --> 00:55:56.199
<v Speaker 2>output of the transmitter. Right, So you attenuated mean you

851
00:55:56.239 --> 00:55:59.079
<v Speaker 2>can't hook your hundred watt radio into your scope? You

852
00:55:59.119 --> 00:56:01.519
<v Speaker 2>want to attenuate it, take a portion of it to

853
00:56:01.559 --> 00:56:04.599
<v Speaker 2>look at. Okay, So that's what they're talking about there.

854
00:56:05.320 --> 00:56:12.119
<v Speaker 2>Why do volt meters have high input impedians You don't

855
00:56:12.119 --> 00:56:13.920
<v Speaker 2>want to load the circuits you're being measureds So what

856
00:56:14.000 --> 00:56:17.119
<v Speaker 2>would be d decreases the loading on circuits being measured.

857
00:56:18.400 --> 00:56:20.880
<v Speaker 2>What is an advantage of a digital volt meter as

858
00:56:20.880 --> 00:56:27.119
<v Speaker 2>compared to an analog meter. I think it has higher precision. Yep,

859
00:56:27.199 --> 00:56:31.000
<v Speaker 2>let's see what when is an analog meter preferred to

860
00:56:31.039 --> 00:56:34.840
<v Speaker 2>a digital meter. So, I think that's when you're adjusting

861
00:56:34.960 --> 00:56:38.880
<v Speaker 2>circuits for minimum or maximum value. If I'm tuning something,

862
00:56:40.320 --> 00:56:43.000
<v Speaker 2>an SWR mater with an analog meter is really nice

863
00:56:43.079 --> 00:56:44.800
<v Speaker 2>to tune. It's you just call them dip meters.

864
00:56:45.519 --> 00:56:45.760
<v Speaker 1>You can.

865
00:56:45.800 --> 00:56:47.599
<v Speaker 2>It's easy with an analog meter to find that that

866
00:56:47.639 --> 00:56:51.119
<v Speaker 2>dip is as opposed to waiting for the digital meter

867
00:56:51.159 --> 00:56:52.000
<v Speaker 2>to settle down, so.

868
00:56:51.920 --> 00:56:53.159
<v Speaker 1>It would be d.

869
00:56:54.320 --> 00:56:56.559
<v Speaker 2>Which of the following can be determined with the directional

870
00:56:56.599 --> 00:57:01.880
<v Speaker 2>watt meter. Let's see antenna front to back ratio. That's

871
00:57:01.880 --> 00:57:07.760
<v Speaker 2>what it sounds like. A directional lot meter. Oh standing,

872
00:57:07.800 --> 00:57:10.639
<v Speaker 2>I'm sorry, I'm thinking the field streak meter. Directional lot

873
00:57:10.679 --> 00:57:13.559
<v Speaker 2>meter you would use to measure forward and reflective power

874
00:57:13.800 --> 00:57:17.280
<v Speaker 2>standing wave ratio, which on the phone must be connected

875
00:57:17.280 --> 00:57:19.840
<v Speaker 2>to an antenna analyzer when it is being measured. For

876
00:57:20.079 --> 00:57:26.760
<v Speaker 2>sw r U, the receiver transmitter antennae feed line thinks

877
00:57:26.960 --> 00:57:32.800
<v Speaker 2>c Yep, you don't need your transmitter connected when you're

878
00:57:32.840 --> 00:57:35.840
<v Speaker 2>checking the antenna and feed line. What effect can strong

879
00:57:35.920 --> 00:57:40.800
<v Speaker 2>signals from nearby transmitters have on an antenna analyzer. They

880
00:57:40.840 --> 00:57:46.239
<v Speaker 2>can desensitize it, receive power. Let's see, since I can

881
00:57:46.239 --> 00:57:49.599
<v Speaker 2>also cause you minds nope, receive power. The interfaces interferes

882
00:57:49.639 --> 00:57:52.880
<v Speaker 2>with the r SWR being. If I'm trying to measure

883
00:57:52.880 --> 00:57:56.159
<v Speaker 2>something locally and Jason's living next door to me and

884
00:57:56.199 --> 00:57:59.039
<v Speaker 2>he powers up his kill A, whatte amplifier he can

885
00:57:59.079 --> 00:58:04.280
<v Speaker 2>affect my my little SWR meter? Which of the phone

886
00:58:04.280 --> 00:58:09.719
<v Speaker 2>can be measured with an intenna analyzer? H power pedants

887
00:58:09.719 --> 00:58:13.360
<v Speaker 2>impedance of the coacs C. All right, Our next section

888
00:58:13.400 --> 00:58:15.920
<v Speaker 2>we're going to talk about is some of the basic

889
00:58:15.960 --> 00:58:21.880
<v Speaker 2>modes in bandwidth, some radio building blocks and transmitters. Okay,

890
00:58:22.239 --> 00:58:25.760
<v Speaker 2>Varying the power or amplitude of a signal to ad

891
00:58:25.760 --> 00:58:30.360
<v Speaker 2>speech or data is called amplitude modulation or am.

892
00:58:31.519 --> 00:58:31.639
<v Speaker 1>Uh.

893
00:58:32.039 --> 00:58:35.039
<v Speaker 2>The information is contained in the signal's envelope the max

894
00:58:35.119 --> 00:58:37.679
<v Speaker 2>values of the instantaneous power for each cycle.

895
00:58:39.039 --> 00:58:40.760
<v Speaker 1>The process of recovering.

896
00:58:40.320 --> 00:58:43.360
<v Speaker 2>Speech or music from an A and envelope is called detection.

897
00:58:44.199 --> 00:58:48.119
<v Speaker 2>So we've got amplitude modulation and then to generate in

898
00:58:48.239 --> 00:58:52.119
<v Speaker 2>detection to decode. AM signals are composed of a carrier

899
00:58:52.440 --> 00:58:53.599
<v Speaker 2>and two sidebands.

900
00:58:53.920 --> 00:58:55.679
<v Speaker 1>It's called upper and lower sideband.

901
00:58:57.719 --> 00:59:00.920
<v Speaker 2>When an AM signal is modulated by a tone, the

902
00:59:00.960 --> 00:59:07.920
<v Speaker 2>two side bands are steady and unchanging. Upper sideband is

903
00:59:08.199 --> 00:59:12.800
<v Speaker 2>higher in frequency than the carrier. Lower sideband is lower frequency.

904
00:59:12.280 --> 00:59:12.920
<v Speaker 1>Than the carrier.

905
00:59:13.239 --> 00:59:15.800
<v Speaker 2>An AM signal with the carrier and one side band

906
00:59:15.800 --> 00:59:21.360
<v Speaker 2>removed is called single sideband. Single sideband transmissions have more

907
00:59:21.440 --> 00:59:25.119
<v Speaker 2>range than AM signals because all the single sideband's power

908
00:59:25.239 --> 00:59:29.039
<v Speaker 2>is contained in a single sideband. The single sideband smaller

909
00:59:29.079 --> 00:59:31.480
<v Speaker 2>bandwidth makes it possible to fit more signals into a

910
00:59:31.519 --> 00:59:37.239
<v Speaker 2>fixed frequency range. Modes that vary the frequency of a

911
00:59:37.280 --> 00:59:40.719
<v Speaker 2>signal to add speech or data in information are called

912
00:59:40.920 --> 00:59:46.559
<v Speaker 2>frequency modulation. Frequency is the frequency is varied is in

913
00:59:46.599 --> 00:59:51.920
<v Speaker 2>proportion to the instantaneous amplitude of the modulated signal. Phase

914
00:59:51.960 --> 00:59:55.199
<v Speaker 2>modulation is created by varying the signal's phase angle.

915
00:59:57.400 --> 00:59:59.280
<v Speaker 1>These signals have a constant.

916
00:59:58.840 --> 01:00:03.559
<v Speaker 2>Power, whether module or not, so AM and PM signals

917
01:00:04.280 --> 01:00:10.079
<v Speaker 2>again if constant power, whether the modulator or not. The

918
01:00:10.159 --> 01:00:13.679
<v Speaker 2>FCC divines bandwidth as the width of a frequency band,

919
01:00:13.760 --> 01:00:17.159
<v Speaker 2>outside of which the mean average power of the transmitted

920
01:00:17.199 --> 01:00:20.559
<v Speaker 2>signal is at least twenty six dB below the mean power.

921
01:00:20.639 --> 01:00:23.519
<v Speaker 2>So what does that mean? So if I'm talking, this

922
01:00:23.559 --> 01:00:27.199
<v Speaker 2>is my voice range. Here somewhere down here is my

923
01:00:27.280 --> 01:00:29.599
<v Speaker 2>noise floor. There is where my noise floors starts. So

924
01:00:29.920 --> 01:00:34.320
<v Speaker 2>when this gets between twenty six dB down from here,

925
01:00:34.400 --> 01:00:37.000
<v Speaker 2>that's where they say, that's your bandwidth from your peak

926
01:00:37.480 --> 01:00:40.920
<v Speaker 2>down to twenty six dB on each side that ratio,

927
01:00:40.960 --> 01:00:42.239
<v Speaker 2>there is your bandwidth.

928
01:00:42.360 --> 01:00:43.280
<v Speaker 1>Okay.

929
01:00:47.039 --> 01:00:49.960
<v Speaker 2>The difference in frequency between the lowest and highest component

930
01:00:50.039 --> 01:00:53.599
<v Speaker 2>of a composite signal is a signals bandwidth. The FCC

931
01:00:53.719 --> 01:00:57.000
<v Speaker 2>limits signal bandwidth so that many stations and types of

932
01:00:57.039 --> 01:01:00.199
<v Speaker 2>signals can share the limited amount of spectrum space. So

933
01:01:01.000 --> 01:01:04.159
<v Speaker 2>we're limited to about three killer hurts on the single

934
01:01:04.239 --> 01:01:08.440
<v Speaker 2>side band. That's why I show, okay, amateur signals. So

935
01:01:08.960 --> 01:01:13.239
<v Speaker 2>here's are different types of signal types their typical bandwidth

936
01:01:13.400 --> 01:01:17.119
<v Speaker 2>AM to six kill hurts, amateur TV six megahurts.

937
01:01:18.280 --> 01:01:20.400
<v Speaker 1>I remember amateur TVs could be up higher.

938
01:01:20.960 --> 01:01:23.679
<v Speaker 2>U single side band voice two to three killer hurts

939
01:01:23.760 --> 01:01:28.760
<v Speaker 2>is typical bandwidth. Digital single side band three killer hurts,

940
01:01:29.119 --> 01:01:31.760
<v Speaker 2>c W one hundred to three hundred hertz, and FM

941
01:01:31.880 --> 01:01:34.760
<v Speaker 2>voice five to sixteen killer hurts, okay.

942
01:01:35.079 --> 01:01:36.840
<v Speaker 1>So what's a link budget when.

943
01:01:38.719 --> 01:01:40.679
<v Speaker 2>You when you add up all the power gain and

944
01:01:40.760 --> 01:01:43.840
<v Speaker 2>losses in a signal transmission from source to receiver.

945
01:01:45.000 --> 01:01:46.679
<v Speaker 1>UH, that's called the link budget.

946
01:01:47.519 --> 01:01:50.039
<v Speaker 2>And amateur radio, this is generally the transmitted power and

947
01:01:50.119 --> 01:01:53.400
<v Speaker 2>antenna gains from the sending station minus the any system

948
01:01:53.480 --> 01:02:00.880
<v Speaker 2>losses the receiving station experiences. Losses result from iyesper refraction, attenuation,

949
01:02:01.079 --> 01:02:04.920
<v Speaker 2>or variety of other causes. Link margin is a difference

950
01:02:04.960 --> 01:02:08.280
<v Speaker 2>between the minimum power that's level needed to receive a

951
01:02:08.320 --> 01:02:11.599
<v Speaker 2>signal and the actual power of the level received signal,

952
01:02:11.639 --> 01:02:15.199
<v Speaker 2>and it's usually measured in d n dB. So if

953
01:02:15.360 --> 01:02:18.599
<v Speaker 2>I'm trying to talk to Jason in Texas from Huntsville

954
01:02:19.360 --> 01:02:23.079
<v Speaker 2>and I'm running thirty watts and he can just barely

955
01:02:23.119 --> 01:02:25.960
<v Speaker 2>hear me, we'll say we've got a link margin of

956
01:02:26.000 --> 01:02:26.719
<v Speaker 2>about zero.

957
01:02:26.840 --> 01:02:27.440
<v Speaker 1>That's perfect.

958
01:02:28.119 --> 01:02:31.960
<v Speaker 2>I crank up my amplifier to one hundred dbt He goes, wow,

959
01:02:32.760 --> 01:02:36.239
<v Speaker 2>I can hear you this much better, ten dB better

960
01:02:36.280 --> 01:02:38.440
<v Speaker 2>than I got a link margin of ten of ten

961
01:02:38.519 --> 01:02:42.960
<v Speaker 2>of ten dB. So's it's how much margin do I

962
01:02:43.000 --> 01:02:44.920
<v Speaker 2>have before he can't hear me anymore?

963
01:02:44.960 --> 01:02:45.880
<v Speaker 1>Right? How much power up?

964
01:02:45.920 --> 01:02:49.000
<v Speaker 2>So that that's your link margin, and my link budget

965
01:02:49.280 --> 01:02:52.960
<v Speaker 2>was my amplifier is this much? My hand in the

966
01:02:52.960 --> 01:02:55.920
<v Speaker 2>gain is this, I lose this much through the atmosphere.

967
01:02:56.320 --> 01:02:59.519
<v Speaker 2>And then on Jason's side, his antenna has this much

968
01:03:00.039 --> 01:03:02.440
<v Speaker 2>as amplifiers this and he can receive it. So it's

969
01:03:02.440 --> 01:03:05.199
<v Speaker 2>that whole link budget, and then the link margin is

970
01:03:05.199 --> 01:03:10.199
<v Speaker 2>how much extra I have to make that communication happen. Okay, So,

971
01:03:10.239 --> 01:03:13.159
<v Speaker 2>what's the name of the process that changes the phase

972
01:03:13.159 --> 01:03:17.000
<v Speaker 2>angle of an RF signal to convey information? Well, that's

973
01:03:17.039 --> 01:03:21.639
<v Speaker 2>phase modulation. B what's the name of the process that

974
01:03:21.719 --> 01:03:25.559
<v Speaker 2>changes the instantaneous frequency of an RF wave to convey information?

975
01:03:26.840 --> 01:03:34.400
<v Speaker 2>All right, instantaneous, I'd be frequency modulation. Okay, what type

976
01:03:34.440 --> 01:03:38.840
<v Speaker 2>of modulation varies the instantaneous power of the RF signal?

977
01:03:39.639 --> 01:03:41.400
<v Speaker 1>That would be amplitude modulation.

978
01:03:43.320 --> 01:03:47.320
<v Speaker 2>Which of the following phone emissions uses the narrowest single

979
01:03:47.840 --> 01:03:55.719
<v Speaker 2>the narrowest band bandwidth single sidebands is the smallest here? Okay?

980
01:03:55.960 --> 01:04:01.599
<v Speaker 2>What is a link budget? Some of transmit power and

981
01:04:01.679 --> 01:04:03.079
<v Speaker 2>gains system laws seen by others.

982
01:04:03.280 --> 01:04:03.880
<v Speaker 1>It's gonna be c.

983
01:04:05.800 --> 01:04:08.639
<v Speaker 2>It's some of the transmit power intended gains minus the

984
01:04:08.679 --> 01:04:10.639
<v Speaker 2>system losses as seen at the receiver.

985
01:04:12.760 --> 01:04:13.760
<v Speaker 1>What's link margin.

986
01:04:15.119 --> 01:04:18.480
<v Speaker 2>That'd be the difference between received power level and minimum required.

987
01:04:18.119 --> 01:04:20.000
<v Speaker 1>Signal level at the input of the receiver.

988
01:04:20.480 --> 01:04:22.960
<v Speaker 2>Nearly all radios are made up of a few fundamental

989
01:04:23.000 --> 01:04:26.519
<v Speaker 2>types of circuits. There's a variety of ways circuits are built,

990
01:04:26.519 --> 01:04:31.320
<v Speaker 2>but basic functions are the same. Radio circuits that perform

991
01:04:32.079 --> 01:04:36.280
<v Speaker 2>signal generation. Processing functions can also be performed on a

992
01:04:36.320 --> 01:04:39.800
<v Speaker 2>digital data by software. In a radio that uses digital

993
01:04:39.800 --> 01:04:44.079
<v Speaker 2>signal processing referred to as a software defined radio.

994
01:04:46.400 --> 01:04:48.679
<v Speaker 1>Filters are used to attenuate.

995
01:04:48.199 --> 01:04:52.480
<v Speaker 2>Or reduce in strength or past signals. A lot of

996
01:04:52.519 --> 01:04:56.800
<v Speaker 2>the modern HF transceivers you buy will have attenuators, filters,

997
01:04:57.159 --> 01:04:59.119
<v Speaker 2>a lot of cool things circuits in them to help

998
01:04:59.159 --> 01:05:03.960
<v Speaker 2>you improve your received performance. Filters are classified by their

999
01:05:03.960 --> 01:05:09.320
<v Speaker 2>response how they act to signals. Range of the signals

1000
01:05:10.159 --> 01:05:12.599
<v Speaker 2>the range of signals that are passed by filters called

1001
01:05:12.599 --> 01:05:16.199
<v Speaker 2>the pass band. The range of signals attenuated by the filter,

1002
01:05:16.239 --> 01:05:21.159
<v Speaker 2>it's called the stop band, also known as rejection. Generic

1003
01:05:21.199 --> 01:05:24.280
<v Speaker 2>filter response curves here are shown. If you look at

1004
01:05:24.320 --> 01:05:26.880
<v Speaker 2>the first example on the left, this is a low

1005
01:05:26.920 --> 01:05:31.119
<v Speaker 2>pass filter. It passes all this these frequencies and then

1006
01:05:31.559 --> 01:05:35.119
<v Speaker 2>attenuates frequencies above. This is passing a low frequency it's

1007
01:05:35.119 --> 01:05:38.159
<v Speaker 2>a low pass filter. Here's a high pass filter. It

1008
01:05:38.159 --> 01:05:43.599
<v Speaker 2>attenuates the lower frequencies than it passes the higher frequency,

1009
01:05:43.719 --> 01:05:48.519
<v Speaker 2>so that's a low pass high pass filter. The cutoff

1010
01:05:48.519 --> 01:05:52.079
<v Speaker 2>frequency is the frequency which the output signal power.

1011
01:05:51.880 --> 01:05:53.039
<v Speaker 1>Is reduced to half.

1012
01:05:53.960 --> 01:05:57.880
<v Speaker 2>So if you remember from our earlier charts, three dB

1013
01:05:58.079 --> 01:06:02.119
<v Speaker 2>down from whatever this level is year wherever three dB is,

1014
01:06:02.159 --> 01:06:05.039
<v Speaker 2>that's called the stop band or the cutoff, the beginning

1015
01:06:05.079 --> 01:06:08.280
<v Speaker 2>of the stop band the cutoff, So it's above a

1016
01:06:08.280 --> 01:06:10.719
<v Speaker 2>low frequenty a low pass filters cut off frequency. The

1017
01:06:10.800 --> 01:06:15.599
<v Speaker 2>tenuation generally increases with frequency, so the tenuation increases, which

1018
01:06:15.679 --> 01:06:20.639
<v Speaker 2>means it gets it rejects the frequencies there. So uh,

1019
01:06:20.679 --> 01:06:23.719
<v Speaker 2>the cutoff is the three d B point of the

1020
01:06:23.760 --> 01:06:27.719
<v Speaker 2>norminal pass band. There's a band pass filter where you,

1021
01:06:27.719 --> 01:06:30.360
<v Speaker 2>you know, attenuate a certain frequencies below a certain amount,

1022
01:06:30.480 --> 01:06:33.000
<v Speaker 2>and you attenuate above a certain amount, and what's in

1023
01:06:33.039 --> 01:06:35.199
<v Speaker 2>the middle is what the band that's passed, called the

1024
01:06:35.239 --> 01:06:35.840
<v Speaker 2>pass band.

1025
01:06:37.679 --> 01:06:38.639
<v Speaker 1>Also a thing called a.

1026
01:06:38.639 --> 01:06:40.840
<v Speaker 2>Notch where you can have a you can have a

1027
01:06:40.880 --> 01:06:44.400
<v Speaker 2>filter come in and pass everything except a frequency you're

1028
01:06:44.480 --> 01:06:48.079
<v Speaker 2>you know, a little band that you're interested in, and

1029
01:06:48.119 --> 01:06:49.159
<v Speaker 2>that's a notch filter.

1030
01:06:49.400 --> 01:06:51.480
<v Speaker 1>Okay, that's the bandwidth of that.

1031
01:06:51.639 --> 01:06:56.039
<v Speaker 2>Let's see, low pass filters passes all frequencies below the

1032
01:06:56.079 --> 01:06:59.800
<v Speaker 2>cutoff of little or no attenuation. UH.

1033
01:07:00.039 --> 01:07:03.000
<v Speaker 1>It is reduced by half. Talk about high pass filters.

1034
01:07:03.039 --> 01:07:07.280
<v Speaker 2>Opposite, it passes things above a certain cutoff frequency. Band

1035
01:07:07.280 --> 01:07:11.039
<v Speaker 2>pass filters have upper and lower cutoff frequencies and pass

1036
01:07:11.119 --> 01:07:12.440
<v Speaker 2>the signals between those two.

1037
01:07:13.320 --> 01:07:13.440
<v Speaker 1>UH.

1038
01:07:13.719 --> 01:07:17.320
<v Speaker 2>Frequency range between upper and lower cutoff is the frequencies bandwidth.

1039
01:07:19.719 --> 01:07:22.760
<v Speaker 2>Opposite of band passes band stop, which is like a

1040
01:07:22.760 --> 01:07:27.480
<v Speaker 2>notch filter. Even those filters past the range of frequencies

1041
01:07:27.480 --> 01:07:30.559
<v Speaker 2>that may attenuate signals in the past band that's called

1042
01:07:30.639 --> 01:07:33.920
<v Speaker 2>insertion loss. All filters are going to have some type

1043
01:07:33.960 --> 01:07:38.320
<v Speaker 2>of insertion loss. The ones I build for my like

1044
01:07:38.360 --> 01:07:40.880
<v Speaker 2>a low pass filter and an LC's.

1045
01:07:40.719 --> 01:07:41.320
<v Speaker 1>They always have.

1046
01:07:41.760 --> 01:07:43.880
<v Speaker 2>It's co could be up to a dB or so

1047
01:07:44.039 --> 01:07:46.119
<v Speaker 2>of loss just going in, so you have to account

1048
01:07:46.159 --> 01:07:49.920
<v Speaker 2>for that in your system design. But and the insertion

1049
01:07:50.039 --> 01:07:53.440
<v Speaker 2>losses is the term for how much you you get

1050
01:07:53.639 --> 01:07:56.199
<v Speaker 2>how much signals lost in the filter itself.

1051
01:07:58.079 --> 01:07:58.880
<v Speaker 1>Outside the past.

1052
01:07:58.920 --> 01:08:02.960
<v Speaker 2>Band attenuation may vary, but maximum attenuation is the ultimates

1053
01:08:03.280 --> 01:08:04.960
<v Speaker 2>the filter's ultimate rejection.

1054
01:08:07.079 --> 01:08:10.360
<v Speaker 1>Okay, another circuits.

1055
01:08:10.039 --> 01:08:13.599
<v Speaker 2>Oscillators they used to consist of an amplifier with the

1056
01:08:13.679 --> 01:08:16.920
<v Speaker 2>feedback from the output to the input.

1057
01:08:16.399 --> 01:08:17.840
<v Speaker 1>The product of.

1058
01:08:17.880 --> 01:08:20.439
<v Speaker 2>Gain and feedback ratio must be greater than one at

1059
01:08:20.479 --> 01:08:25.439
<v Speaker 2>the frequency of oscillation, and this is the basic building block,

1060
01:08:25.520 --> 01:08:28.279
<v Speaker 2>basic premise of all the osc layers we use in

1061
01:08:28.359 --> 01:08:29.439
<v Speaker 2>our radio equipment.

1062
01:08:31.119 --> 01:08:31.600
<v Speaker 1>You've got an.

1063
01:08:31.560 --> 01:08:33.720
<v Speaker 2>Amplifier with feed some of it back to itself, and

1064
01:08:33.760 --> 01:08:38.800
<v Speaker 2>it starts to oscillate. An ostlator consists of an amplifier

1065
01:08:38.840 --> 01:08:43.760
<v Speaker 2>that increases signal amplitude gain and feedback circuit to route

1066
01:08:43.800 --> 01:08:46.840
<v Speaker 2>some of the amplifier's output back to the input. Oscillator

1067
01:08:46.920 --> 01:08:50.079
<v Speaker 2>circuits may include a filter so that feedback is present

1068
01:08:50.319 --> 01:08:55.439
<v Speaker 2>at only the intended frequency. The oscillator output frequency can

1069
01:08:55.479 --> 01:09:03.159
<v Speaker 2>be fixed or variable. An LC oscillator feedback circuit consists

1070
01:09:03.199 --> 01:09:06.640
<v Speaker 2>of an inductor and a capacitor in parallel or series

1071
01:09:07.079 --> 01:09:12.279
<v Speaker 2>that form a resonant circuit, often called a tank circuit

1072
01:09:12.439 --> 01:09:16.279
<v Speaker 2>because of their ability to store energy. The resonant frequency

1073
01:09:16.319 --> 01:09:19.600
<v Speaker 2>of an LC circuit, determined by its values, is the

1074
01:09:19.640 --> 01:09:25.359
<v Speaker 2>frequency of the oscillator. The output frequency of a variable

1075
01:09:25.399 --> 01:09:29.479
<v Speaker 2>frequency oscillator VFO can be adjusted by changing the L

1076
01:09:29.600 --> 01:09:32.319
<v Speaker 2>or C. VFOs are used to tune a radio to

1077
01:09:32.359 --> 01:09:38.399
<v Speaker 2>different frequencies. Two other widely used VFO circuits are the

1078
01:09:38.439 --> 01:09:43.600
<v Speaker 2>phase lock loop PLL in the direct digital synthesizer DDS.

1079
01:09:45.239 --> 01:09:49.960
<v Speaker 2>The DDS is controlled by software. It's comparably stable. The

1080
01:09:50.039 --> 01:09:54.680
<v Speaker 2>crystal oscillators used as the high stability VFO and most

1081
01:09:54.720 --> 01:09:57.239
<v Speaker 2>current transceivers, most of them have a DDS in them.

1082
01:09:57.279 --> 01:10:04.640
<v Speaker 2>These days, mixers can change signals from one frequency to another.

1083
01:10:06.279 --> 01:10:09.720
<v Speaker 2>A mixer circuit combined signals with two frequencies F one

1084
01:10:09.760 --> 01:10:14.239
<v Speaker 2>and F two and produces signals with the sum in difference.

1085
01:10:13.880 --> 01:10:16.880
<v Speaker 1>Frequencies at at its out at its output. And that's

1086
01:10:16.880 --> 01:10:18.199
<v Speaker 1>a term called header dining.

1087
01:10:20.000 --> 01:10:22.920
<v Speaker 2>Example, if I've got a frequency of fourteen point oh

1088
01:10:22.960 --> 01:10:26.000
<v Speaker 2>five megahertz and an F two of three point three five,

1089
01:10:26.720 --> 01:10:29.439
<v Speaker 2>I'm going to get the gain in difference of those

1090
01:10:29.479 --> 01:10:36.439
<v Speaker 2>two frequencies, so i would have a frequency of fourteen

1091
01:10:36.640 --> 01:10:42.760
<v Speaker 2>point five to three and fourteen point oh two six.

1092
01:10:45.319 --> 01:10:49.199
<v Speaker 2>A multiplier similar to a mixer. It creates a harmonic

1093
01:10:49.359 --> 01:10:53.359
<v Speaker 2>of the input frequency. Multipliers are often used when a

1094
01:10:53.399 --> 01:10:56.520
<v Speaker 2>stable VHF or UHF signal is required that cannot be

1095
01:10:56.600 --> 01:11:01.640
<v Speaker 2>generated directly at VHF or UHF low frequency oscillator supplies

1096
01:11:01.680 --> 01:11:04.439
<v Speaker 2>the multiplier input and the output is tuned to the

1097
01:11:04.479 --> 01:11:09.239
<v Speaker 2>desired harmonic of the output signal. Also used in FM

1098
01:11:09.239 --> 01:11:16.960
<v Speaker 2>transmitters use a lot there modulators. A modulator adds any

1099
01:11:17.000 --> 01:11:20.159
<v Speaker 2>information to a carrier signal by varying the carrier's amplitude,

1100
01:11:20.239 --> 01:11:25.479
<v Speaker 2>frequency or phase. It can be used for AM FM

1101
01:11:25.560 --> 01:11:34.880
<v Speaker 2>for single sideband amplitude modulation, there's three types of AM

1102
01:11:35.119 --> 01:11:39.119
<v Speaker 2>three types of AM signals. Full AM has both the

1103
01:11:39.159 --> 01:11:42.399
<v Speaker 2>sidebands and the carrier. The carrier is represented by the

1104
01:11:42.479 --> 01:11:45.159
<v Speaker 2>vertical line in the middle of the sidebands over here,

1105
01:11:46.800 --> 01:11:50.520
<v Speaker 2>and the sidebands contain data, can't contain speech or data,

1106
01:11:50.760 --> 01:11:54.479
<v Speaker 2>and the signals have been used to can't have been

1107
01:11:54.560 --> 01:11:58.880
<v Speaker 2>used to modulate the carrier. Double sideband removes the carrier

1108
01:12:00.279 --> 01:12:03.720
<v Speaker 2>is gone, but has the same bandwidth and information in

1109
01:12:03.760 --> 01:12:07.159
<v Speaker 2>it that the full AM signal had in it. And

1110
01:12:07.199 --> 01:12:10.479
<v Speaker 2>then the single sideband removes one of the sidebands and

1111
01:12:10.520 --> 01:12:13.119
<v Speaker 2>the carrier. And this is the lowest bandwidth of the

1112
01:12:13.159 --> 01:12:17.760
<v Speaker 2>three and also the lowest amount of power that you need.

1113
01:12:18.600 --> 01:12:22.880
<v Speaker 2>Double sideband can be produced by by balanced modulator, which

1114
01:12:22.960 --> 01:12:25.239
<v Speaker 2>is a special mixer, where F one is the carrier

1115
01:12:25.239 --> 01:12:28.840
<v Speaker 2>and F two is the modulator. Single sideband is generated

1116
01:12:28.880 --> 01:12:32.520
<v Speaker 2>by removing the unwadded side unwanted sideband and carrier and

1117
01:12:32.600 --> 01:12:37.359
<v Speaker 2>carrier with a filter or by combining signals with certain

1118
01:12:37.359 --> 01:12:40.239
<v Speaker 2>phase relationships called the phasing method. So there's a filtered

1119
01:12:40.319 --> 01:12:44.880
<v Speaker 2>method and phasing method to remove the unwanted sideband using

1120
01:12:44.920 --> 01:12:49.479
<v Speaker 2>only one sideband uses users transmitted output power more effectively.

1121
01:12:50.760 --> 01:12:50.880
<v Speaker 1>UH.

1122
01:12:50.960 --> 01:12:56.199
<v Speaker 2>Here's a here's a diagram of a frequency or phase modulation.

1123
01:12:57.199 --> 01:13:01.560
<v Speaker 2>You have a reactant modulator, you have an oscillator audio input,

1124
01:13:01.760 --> 01:13:08.640
<v Speaker 2>and this will generate to your double sideband output audio input.

1125
01:13:08.680 --> 01:13:12.800
<v Speaker 2>Here react its modulator, an oscillator in, and you get

1126
01:13:12.800 --> 01:13:17.439
<v Speaker 2>the phase modulated out frequency modulation. The signal frequency varies

1127
01:13:17.479 --> 01:13:21.920
<v Speaker 2>in proportion to modulating the signal's amplitude. It's called deviation.

1128
01:13:23.359 --> 01:13:23.439
<v Speaker 1>UH.

1129
01:13:23.920 --> 01:13:28.439
<v Speaker 2>Phase modulation. Just the deviation varies with both amplitude and

1130
01:13:28.560 --> 01:13:33.640
<v Speaker 2>frequency of the modulated signal produced by reactance modulator connected

1131
01:13:33.680 --> 01:13:38.840
<v Speaker 2>to a tuned or if amplifier following the oscillator. When

1132
01:13:38.880 --> 01:13:41.920
<v Speaker 2>modulation is applied, the phase of the carrier will will

1133
01:13:42.119 --> 01:13:45.439
<v Speaker 2>not not be changed, but the average frequency will not.

1134
01:13:45.600 --> 01:13:48.439
<v Speaker 2>It's going to read that again. When modulation is applied,

1135
01:13:48.920 --> 01:13:51.840
<v Speaker 2>the phase of the carrier will be changed, but the

1136
01:13:51.920 --> 01:13:57.039
<v Speaker 2>average frequency will not change, okay, and the sound identical

1137
01:13:57.119 --> 01:13:59.239
<v Speaker 2>on the air. If you listen to frequency modulation or

1138
01:13:59.239 --> 01:14:03.560
<v Speaker 2>phase modulation, they would sound the same all about the

1139
01:14:04.239 --> 01:14:08.800
<v Speaker 2>detector also called IQ modulation because of the I in

1140
01:14:08.880 --> 01:14:13.880
<v Speaker 2>Q signals that create the modulated output signal that this

1141
01:14:14.039 --> 01:14:19.560
<v Speaker 2>is quadrant quadrature modulation. This is used to transmit digital signals,

1142
01:14:19.600 --> 01:14:22.760
<v Speaker 2>but different combinations of im q signals can create signals

1143
01:14:22.760 --> 01:14:27.079
<v Speaker 2>with any form of modulation. The RF output of the

1144
01:14:27.119 --> 01:14:29.920
<v Speaker 2>combiner consists of a pair of modulated signals that have

1145
01:14:30.079 --> 01:14:34.399
<v Speaker 2>carrier signals ninety degrees different in phase. Widely used in

1146
01:14:34.479 --> 01:14:39.039
<v Speaker 2>software defined radios, which traditionally analogs. Components have been replaced

1147
01:14:39.039 --> 01:14:42.479
<v Speaker 2>by programming that is, filtering, modulation and detection.

1148
01:14:42.920 --> 01:14:43.640
<v Speaker 1>That's where you'll.

1149
01:14:43.520 --> 01:14:47.960
<v Speaker 2>Find quadrature modulation. Here's a figure on the right that

1150
01:14:48.039 --> 01:14:51.680
<v Speaker 2>has a block diagram of the I in Q inputs

1151
01:14:51.840 --> 01:14:57.359
<v Speaker 2>of ninety degrees phase shift network in the middle. Quadrature

1152
01:14:57.399 --> 01:14:58.960
<v Speaker 2>simply means phase shifted.

1153
01:14:58.640 --> 01:14:59.520
<v Speaker 1>By ninety degrees.

1154
01:15:02.000 --> 01:15:04.199
<v Speaker 2>Which of the following are basic components of a sine

1155
01:15:04.199 --> 01:15:05.039
<v Speaker 2>wave oscillator.

1156
01:15:06.520 --> 01:15:07.760
<v Speaker 1>Let's see.

1157
01:15:11.079 --> 01:15:15.520
<v Speaker 2>D filtered and amplifier operating in a feedback loop. What

1158
01:15:15.680 --> 01:15:19.720
<v Speaker 2>determines the frequency of an LC oscillator. That'd be the

1159
01:15:19.800 --> 01:15:23.520
<v Speaker 2>inductance and capassitance of the tank circuit. C. Which of

1160
01:15:23.600 --> 01:15:27.520
<v Speaker 2>the following is characteristic of a digitally direct digital synthesizer

1161
01:15:31.199 --> 01:15:36.359
<v Speaker 2>through the stable crystal d barable output frequency with the

1162
01:15:36.359 --> 01:15:41.119
<v Speaker 2>stability of a crystal oscillator. What term specifies a filter's

1163
01:15:41.399 --> 01:15:45.439
<v Speaker 2>attenuation inside its past band? That would be the insertion

1164
01:15:45.600 --> 01:15:50.439
<v Speaker 2>loss A. What is the phase difference between the I

1165
01:15:50.479 --> 01:15:53.960
<v Speaker 2>and q RF signals that software defined radio equipment uses

1166
01:15:53.960 --> 01:15:59.399
<v Speaker 2>for modulation and demodulation, So it's ninety degrees out of phase? B.

1167
01:16:00.760 --> 01:16:04.520
<v Speaker 2>What is an advantage of using IQ modulation with software

1168
01:16:04.560 --> 01:16:11.640
<v Speaker 2>defined SDRs? Appropriate processing? Right? So it allows you to

1169
01:16:12.319 --> 01:16:14.199
<v Speaker 2>with the right processing, you can do a bunch of

1170
01:16:14.239 --> 01:16:17.960
<v Speaker 2>different stuff if you've got the IQ signals. B. Which

1171
01:16:17.960 --> 01:16:20.840
<v Speaker 2>of the following functions is determined by software and a

1172
01:16:20.880 --> 01:16:28.520
<v Speaker 2>software defined radio can be all those can do filtering, detection, modulation,

1173
01:16:29.119 --> 01:16:33.000
<v Speaker 2>all those things digitally. What is the frequency above which

1174
01:16:33.000 --> 01:16:35.920
<v Speaker 2>a low pass filters output power is less than half

1175
01:16:35.960 --> 01:16:42.000
<v Speaker 2>the input power? So that's the cutoff frequency. What term

1176
01:16:42.079 --> 01:16:45.880
<v Speaker 2>specifies a filtered maximum ability to reject signals out of

1177
01:16:45.920 --> 01:16:52.239
<v Speaker 2>its band? That's the maximum? Would be the ultimate rejection.

1178
01:16:55.000 --> 01:16:57.520
<v Speaker 2>The bandwidth of a band pass filter is measured between

1179
01:16:57.800 --> 01:17:01.840
<v Speaker 2>what two frequencies of a band pass built You've got

1180
01:17:01.880 --> 01:17:04.760
<v Speaker 2>to upper and lower, so UH be the upper and

1181
01:17:04.840 --> 01:17:09.079
<v Speaker 2>lower half half power cut off points. A. What emission

1182
01:17:09.119 --> 01:17:13.199
<v Speaker 2>is produced by a reactance modulator connected to a transmitted

1183
01:17:13.399 --> 01:17:17.880
<v Speaker 2>transmitter r F stage? So reactance modulator is used in

1184
01:17:18.119 --> 01:17:24.359
<v Speaker 2>UH phase modulation B. What's another term for mixing of

1185
01:17:24.439 --> 01:17:29.439
<v Speaker 2>two r F signals UH header dining. What is the

1186
01:17:29.479 --> 01:17:32.560
<v Speaker 2>stage in a v h F FM transmitter that generates

1187
01:17:32.560 --> 01:17:35.920
<v Speaker 2>a harmonic of lower frequency signal to reach the desired

1188
01:17:35.920 --> 01:17:39.399
<v Speaker 2>operating frequency. So that'd be a multiplier, right, You're taking

1189
01:17:39.399 --> 01:17:42.319
<v Speaker 2>a lower frequency to get a higher one, so you're multiplying.

1190
01:17:42.680 --> 01:17:48.520
<v Speaker 2>Be multiplier. What combination of a mixer's local oscillator and

1191
01:17:48.680 --> 01:17:52.760
<v Speaker 2>r F input frequency is found in the output? Be

1192
01:17:52.880 --> 01:17:56.840
<v Speaker 2>the sum in the difference member f F plus f

1193
01:17:56.920 --> 01:17:59.399
<v Speaker 2>plus f one F minus f one.

1194
01:17:59.439 --> 01:18:01.279
<v Speaker 1>You know, so some of the difference.

1195
01:18:02.800 --> 01:18:05.000
<v Speaker 2>Now we're gona talk a little bit about CW transmitters.

1196
01:18:07.000 --> 01:18:10.119
<v Speaker 2>Simplest transmitter consists of an oscillator, an amplifier, and a

1197
01:18:10.199 --> 01:18:14.239
<v Speaker 2>means of turning the signal on off or the key

1198
01:18:14.359 --> 01:18:18.720
<v Speaker 2>or key Here a signal. A single crystal oscillator can

1199
01:18:18.800 --> 01:18:21.279
<v Speaker 2>be replaced with a variable frequency oscillator to allow the

1200
01:18:21.279 --> 01:18:24.439
<v Speaker 2>transmitter to be tuned to different frequencies. So here's your

1201
01:18:24.479 --> 01:18:28.640
<v Speaker 2>basic building block. I've got an oscillator, amplifier, and an

1202
01:18:28.680 --> 01:18:33.760
<v Speaker 2>on off switch and an antenna. Okay, By changing the

1203
01:18:33.800 --> 01:18:37.359
<v Speaker 2>frequency of the of the local oscillator, the VFOs can

1204
01:18:37.439 --> 01:18:39.800
<v Speaker 2>now be shifted from band to band, crying a multi

1205
01:18:39.840 --> 01:18:43.279
<v Speaker 2>band transmitter. So now if I've got an oscillator, if

1206
01:18:43.319 --> 01:18:45.960
<v Speaker 2>I can, I can change the frequency of the oscillator,

1207
01:18:46.000 --> 01:18:48.960
<v Speaker 2>in this case through through some crystals or a veriable

1208
01:18:49.000 --> 01:18:53.039
<v Speaker 2>frequency oscillator. Now I've got something I can operate on

1209
01:18:53.199 --> 01:18:56.960
<v Speaker 2>different bands. Substituting those the circuits to create a single

1210
01:18:57.000 --> 01:19:01.039
<v Speaker 2>sideband signal for the VFO creates a multiband. Now you've

1211
01:19:01.039 --> 01:19:05.960
<v Speaker 2>got a single sideband transmitter. You've got a balance modulator,

1212
01:19:06.039 --> 01:19:10.479
<v Speaker 2>you've got some UH bandpass filters, a mixer. Now I'm

1213
01:19:10.479 --> 01:19:13.159
<v Speaker 2>getting more of a radio that can do voice and

1214
01:19:13.319 --> 01:19:17.319
<v Speaker 2>c W voice signals from a micro process by speech

1215
01:19:17.359 --> 01:19:20.560
<v Speaker 2>amplifier input to the balance mixture. This is a single

1216
01:19:20.600 --> 01:19:25.000
<v Speaker 2>sideband phone transmitter. The variable frequency oscillator is the other

1217
01:19:25.079 --> 01:19:29.720
<v Speaker 2>input to the balance modulator. The output is a digital

1218
01:19:31.039 --> 01:19:36.479
<v Speaker 2>single is a double sideband signal, so the filter is

1219
01:19:36.560 --> 01:19:40.039
<v Speaker 2>used to remove the undesired sideband producing in a single sideband.

1220
01:19:40.119 --> 01:19:44.239
<v Speaker 2>So in your modern HF radio, when you switch between

1221
01:19:44.439 --> 01:19:47.800
<v Speaker 2>AM between upper and lower sideband, you either switching you're

1222
01:19:47.800 --> 01:19:50.039
<v Speaker 2>switching in and out one of these filters, so you're

1223
01:19:50.079 --> 01:19:54.479
<v Speaker 2>generating the double sideband, and UH based on upper lower

1224
01:19:54.560 --> 01:19:56.520
<v Speaker 2>sideband is going to select which one of those you're

1225
01:19:56.520 --> 01:19:59.439
<v Speaker 2>going to transmit, so they're both produced in your radio,

1226
01:19:59.479 --> 01:20:02.000
<v Speaker 2>but you FI filter out one the one that you

1227
01:20:02.079 --> 01:20:06.840
<v Speaker 2>want to use. Distortion anywhere in the transmit chain will

1228
01:20:06.880 --> 01:20:11.399
<v Speaker 2>generate unwanted sperienced signals called harmonics or mixing products or splattered.

1229
01:20:13.479 --> 01:20:16.000
<v Speaker 2>An FM transmitter looks like this picture here. I've got

1230
01:20:16.000 --> 01:20:22.079
<v Speaker 2>a microphone, a speech amplifier, reractans modulator, an oscillator, multiplier, filter,

1231
01:20:22.239 --> 01:20:28.359
<v Speaker 2>and amplifier. So the carrier and modulation are generated at

1232
01:20:28.680 --> 01:20:32.800
<v Speaker 2>relatively low frequencies in FM transmitters, and the mosleated signals

1233
01:20:32.840 --> 01:20:37.000
<v Speaker 2>and multiplied to the desired output frequency. The amount of

1234
01:20:37.199 --> 01:20:44.239
<v Speaker 2>signal deviation is also multiplied, so modulation and frequency changing

1235
01:20:44.279 --> 01:20:49.000
<v Speaker 2>are performed differently. In FM transmitters is much more practical

1236
01:20:49.039 --> 01:20:51.640
<v Speaker 2>to generate the signal at low frequency and multiply it

1237
01:20:51.680 --> 01:20:55.600
<v Speaker 2>to reach the high the desired band and an example

1238
01:20:55.640 --> 01:20:59.600
<v Speaker 2>in a two meter FM transmitter, the modulated oscillator frequencies

1239
01:20:59.640 --> 01:21:04.920
<v Speaker 2>approut from the twelve megahertz and multiplies and multipliers select

1240
01:21:04.960 --> 01:21:08.560
<v Speaker 2>the twelfth harmonic The transmission are now put a one

1241
01:21:08.680 --> 01:21:11.159
<v Speaker 2>forty six dot five to two. For example, the oscillator

1242
01:21:11.199 --> 01:21:13.600
<v Speaker 2>must divided by twelve or a twelve point twenty one

1243
01:21:13.680 --> 01:21:14.600
<v Speaker 2>mega hurt signal.

1244
01:21:17.560 --> 01:21:19.880
<v Speaker 1>The frequency deviation is also multiplied.

1245
01:21:20.880 --> 01:21:25.279
<v Speaker 2>For example, if the five two mega hurt signal is

1246
01:21:25.399 --> 01:21:29.279
<v Speaker 2>to have the standard deviation of five megaherts, the maximum

1247
01:21:29.359 --> 01:21:33.600
<v Speaker 2>oscillator deviation would be five divided by twelve or zero

1248
01:21:33.760 --> 01:21:36.479
<v Speaker 2>point four to one six megaherts or four hundred and

1249
01:21:36.520 --> 01:21:41.279
<v Speaker 2>sixteen point seven hurts. Okay, because it gets multiplied along

1250
01:21:41.439 --> 01:21:46.600
<v Speaker 2>with the frequency multiplication for the FM transmission, Carson's rule

1251
01:21:46.680 --> 01:21:50.319
<v Speaker 2>provides a good approximation of FM signals bandwidth. The bandwidth

1252
01:21:50.399 --> 01:21:53.159
<v Speaker 2>is equal to two times the peak deviation plus the

1253
01:21:53.239 --> 01:21:57.680
<v Speaker 2>highest moduling frequency. In our example, if an FM phone

1254
01:21:57.720 --> 01:22:00.960
<v Speaker 2>signal's peak deviation is limited to five killer hurts and

1255
01:22:01.039 --> 01:22:05.359
<v Speaker 2>the highest modulating frequency is three killer hurts. Then bandwidth

1256
01:22:05.479 --> 01:22:08.520
<v Speaker 2>is equal to two times five plus three or sixteen

1257
01:22:08.640 --> 01:22:13.720
<v Speaker 2>killer herts. So bandwidth is equal to two times the

1258
01:22:13.760 --> 01:22:21.960
<v Speaker 2>peak deviation plus the highest modulating frequency. Over signal quality,

1259
01:22:22.239 --> 01:22:25.159
<v Speaker 2>you can overmodulate on AM signals an AM or single

1260
01:22:25.279 --> 01:22:28.960
<v Speaker 2>side bend signal that varies excessively in responding to the

1261
01:22:29.039 --> 01:22:34.439
<v Speaker 2>modulation signal, you'll have distorted transmitted audio. And if you

1262
01:22:34.479 --> 01:22:37.760
<v Speaker 2>speak too loudly, or mike gains too high, or audio

1263
01:22:37.840 --> 01:22:40.880
<v Speaker 2>gains too high, you can have overmodulation and distort your audio.

1264
01:22:44.079 --> 01:22:48.399
<v Speaker 2>Modulation envelope of an AM signal. Look at the signal

1265
01:22:48.439 --> 01:22:52.399
<v Speaker 2>here on the left, very nice, uh looking AM signal.

1266
01:22:53.000 --> 01:22:56.399
<v Speaker 2>You've got the This is the audio right, what's in?

1267
01:22:56.520 --> 01:23:01.319
<v Speaker 2>Here's your modulation frequency. Here's your audio for sequency in

1268
01:23:01.399 --> 01:23:03.399
<v Speaker 2>this particular one, this is a you put in like

1269
01:23:03.560 --> 01:23:06.199
<v Speaker 2>a kill hurts tone. You got a single tone. That's

1270
01:23:06.239 --> 01:23:10.000
<v Speaker 2>what looks very very nice. If I start to overmodulate,

1271
01:23:10.079 --> 01:23:12.279
<v Speaker 2>you'll see there's time share where there's stuff cuts off,

1272
01:23:12.800 --> 01:23:15.439
<v Speaker 2>and I get other spurious signals down there in the

1273
01:23:15.520 --> 01:23:22.000
<v Speaker 2>frequency spectrum. So a is a poorly modulated signal, whoops

1274
01:23:22.399 --> 01:23:27.239
<v Speaker 2>over there at this as a properly modulated signal B

1275
01:23:27.479 --> 01:23:30.000
<v Speaker 2>is an example of a cutoff. Transmitter output is turned

1276
01:23:30.039 --> 01:23:34.399
<v Speaker 2>off instead of following the modulated signal, so it sounds choppy,

1277
01:23:34.520 --> 01:23:35.319
<v Speaker 2>sounds distorted.

1278
01:23:38.760 --> 01:23:39.199
<v Speaker 1>Transmit.

1279
01:23:40.119 --> 01:23:42.399
<v Speaker 2>If you have cut off the transmitter output is turned

1280
01:23:42.439 --> 01:23:45.960
<v Speaker 2>off instead of following the modulated signal. Flat topping occurs

1281
01:23:46.159 --> 01:23:49.239
<v Speaker 2>when the transmitter output reaches a maximum limit. It cannot

1282
01:23:49.279 --> 01:23:54.119
<v Speaker 2>increase further even though the moduling signal is increasing. That's

1283
01:23:54.159 --> 01:23:56.800
<v Speaker 2>why it clips at the top and it stops transmitting.

1284
01:23:56.880 --> 01:24:00.359
<v Speaker 2>It's gonna sound choppy and distorted. If the outputs was

1285
01:24:00.359 --> 01:24:03.880
<v Speaker 2>completely cut off between peaks, the result is called carrier cutoff.

1286
01:24:04.760 --> 01:24:08.760
<v Speaker 2>Both types of overmodulation cause interference by genering spurious signals

1287
01:24:09.479 --> 01:24:13.159
<v Speaker 2>that is, distortion products beyond normal signal bandwidth called splatter

1288
01:24:17.199 --> 01:24:21.800
<v Speaker 2>AD and automatic level control or ALC circuit, and the

1289
01:24:21.880 --> 01:24:25.960
<v Speaker 2>transmitter helps prevent this type of over modulation and reduces

1290
01:24:26.000 --> 01:24:30.000
<v Speaker 2>output power during voice peaks. It's controlled by properly setting

1291
01:24:30.039 --> 01:24:32.479
<v Speaker 2>the transmitted audio or might gain and should be adjusted

1292
01:24:32.560 --> 01:24:38.199
<v Speaker 2>to activate only on your voice peaks. There's a two

1293
01:24:38.239 --> 01:24:41.720
<v Speaker 2>tone test is used to monitor transmitter linearity, which keeps

1294
01:24:41.720 --> 01:24:45.039
<v Speaker 2>a signal clean. It only needs to be performed occasionally

1295
01:24:45.119 --> 01:24:48.800
<v Speaker 2>denote appropriate gain settings and two level adjustments. Two tone

1296
01:24:48.880 --> 01:24:52.359
<v Speaker 2>comes from the use of two non harmonically related harmonically

1297
01:24:52.399 --> 01:24:57.840
<v Speaker 2>related signals for the test. Most radios display carrier frequency

1298
01:24:57.960 --> 01:25:02.880
<v Speaker 2>of a single sideband. Actual signal lies between above the

1299
01:25:03.159 --> 01:25:06.079
<v Speaker 2>upper sideband or low below the lower sideband, so your

1300
01:25:06.119 --> 01:25:09.359
<v Speaker 2>dial frequency is not exactly where your audio starts, it's

1301
01:25:09.399 --> 01:25:13.399
<v Speaker 2>where your carrier would be. Each single sideband occupies three

1302
01:25:13.520 --> 01:25:16.399
<v Speaker 2>killer hurts, so you'll need to stay far away from

1303
01:25:16.600 --> 01:25:19.560
<v Speaker 2>edge from the edge of frequency privileges to avoid ill

1304
01:25:19.600 --> 01:25:24.640
<v Speaker 2>legal transmissions. So for generals using lower sideband on forty meters,

1305
01:25:26.079 --> 01:25:28.520
<v Speaker 2>operate with a career frequency of at least three killer

1306
01:25:28.560 --> 01:25:31.800
<v Speaker 2>hurts above the edge of the band segment. Because remember

1307
01:25:31.920 --> 01:25:33.880
<v Speaker 2>at forty meters for lower sideband, you want to be

1308
01:25:33.960 --> 01:25:38.680
<v Speaker 2>three killer hurts above, so seven point one seven eight,

1309
01:25:39.359 --> 01:25:42.399
<v Speaker 2>because we're allowed to go down to seven point one

1310
01:25:42.600 --> 01:25:45.359
<v Speaker 2>seven five. So that's my low end and I'm on

1311
01:25:45.479 --> 01:25:48.079
<v Speaker 2>lower sideband, I want to put my dial frequency on

1312
01:25:48.199 --> 01:25:51.520
<v Speaker 2>seven point one seven eight. When sidebands extend from the

1313
01:25:51.560 --> 01:25:54.439
<v Speaker 2>carrier toward the band edge or a band segment edge,

1314
01:25:54.720 --> 01:25:58.600
<v Speaker 2>operate with the displayed carrier frequency no closer than three

1315
01:25:58.680 --> 01:26:00.800
<v Speaker 2>killer hurts of the edge of the band, so your

1316
01:26:00.840 --> 01:26:02.159
<v Speaker 2>signal is sure to be cleaned.

1317
01:26:02.239 --> 01:26:03.159
<v Speaker 1>So if I'm on.

1318
01:26:05.119 --> 01:26:09.640
<v Speaker 2>Twenty meters here and I'm upper sideband signal and here's

1319
01:26:09.680 --> 01:26:11.920
<v Speaker 2>the edge of the band, I want to make sure

1320
01:26:12.039 --> 01:26:14.960
<v Speaker 2>I'm less than the edge, so I'm not right up

1321
01:26:15.000 --> 01:26:18.000
<v Speaker 2>against it. I don't want to put my dial frequency

1322
01:26:18.039 --> 01:26:21.960
<v Speaker 2>on fourteen three three fifty because then my upper sidebands

1323
01:26:22.000 --> 01:26:25.439
<v Speaker 2>out of outer band. Here's a forty meter example. It's

1324
01:26:25.479 --> 01:26:27.319
<v Speaker 2>a lower sideband. You want to make sure you're not

1325
01:26:27.560 --> 01:26:30.199
<v Speaker 2>This is the seven point one seventy five is the

1326
01:26:30.319 --> 01:26:33.760
<v Speaker 2>low end general place that we can We can't go

1327
01:26:33.840 --> 01:26:35.960
<v Speaker 2>below that, so you want to make sure you're set

1328
01:26:36.039 --> 01:26:38.239
<v Speaker 2>up above that. At least three kill hurts up above.

1329
01:26:38.960 --> 01:26:42.520
<v Speaker 2>So another circuit speech processing. The average power of an

1330
01:26:42.560 --> 01:26:45.079
<v Speaker 2>AM or single sideband signal is much lower than c

1331
01:26:45.359 --> 01:26:49.880
<v Speaker 2>W when transmitted over HF and AM signal. In the

1332
01:26:49.960 --> 01:26:53.319
<v Speaker 2>presence of noise interference, et cetera, the received signal can

1333
01:26:53.359 --> 01:26:58.680
<v Speaker 2>be difficult to understand. Speech processing increases the average power

1334
01:26:58.720 --> 01:27:02.000
<v Speaker 2>of the signal without the arding it, which results in

1335
01:27:02.079 --> 01:27:06.640
<v Speaker 2>improved intelligibility of the received signal in poor conditions. So

1336
01:27:06.960 --> 01:27:09.239
<v Speaker 2>a lot of the modern radios have speech processing. You

1337
01:27:09.279 --> 01:27:13.520
<v Speaker 2>can try to on or off and it works pretty good,

1338
01:27:13.560 --> 01:27:15.039
<v Speaker 2>but you have to make sure you got it all

1339
01:27:15.079 --> 01:27:18.640
<v Speaker 2>set up right and adjusted correctly. Speech processors can also

1340
01:27:18.720 --> 01:27:22.760
<v Speaker 2>amplify a low level background noise, reducing intelligibility, So careful

1341
01:27:22.760 --> 01:27:29.840
<v Speaker 2>of that, uh CEW key clicks sharp transient clicking sounds

1342
01:27:29.880 --> 01:27:33.000
<v Speaker 2>heard on adjacent frequencies as a transmitter turns on and

1343
01:27:33.079 --> 01:27:36.800
<v Speaker 2>off too rapidly during the cd W transmissions, or if

1344
01:27:36.840 --> 01:27:39.800
<v Speaker 2>transmitter turns on and off erratically, those are called key clicks.

1345
01:27:41.760 --> 01:27:45.960
<v Speaker 2>CWA forms can be inspected using a monitor in a celloscope,

1346
01:27:46.000 --> 01:27:48.359
<v Speaker 2>and you can see what the key clicks would look like.

1347
01:27:49.079 --> 01:27:53.560
<v Speaker 2>Just show one without it, but uh, you know, there's

1348
01:27:53.600 --> 01:27:55.199
<v Speaker 2>a way you can see if you've got key clicks

1349
01:27:55.239 --> 01:27:57.039
<v Speaker 2>going on. And if you've got them, you've got to

1350
01:27:57.119 --> 01:28:03.359
<v Speaker 2>turn down your your modulation a little bit. What control

1351
01:28:03.479 --> 01:28:06.680
<v Speaker 2>is typically adjusted for proper ALC setting on a single

1352
01:28:06.720 --> 01:28:14.359
<v Speaker 2>sideband transmit audio and microphone game? Okay, what signal are

1353
01:28:14.359 --> 01:28:18.399
<v Speaker 2>yoused to conduct the two tone test? Two audio signals

1354
01:28:19.239 --> 01:28:22.439
<v Speaker 2>that are not harmonically related, that's the key non harmonically

1355
01:28:22.520 --> 01:28:26.640
<v Speaker 2>related signals, So that would be be what type of

1356
01:28:26.720 --> 01:28:32.640
<v Speaker 2>transmitter performance does a two tone test analyze linearity is

1357
01:28:32.760 --> 01:28:36.359
<v Speaker 2>usually linearity. How linear it is a What is the

1358
01:28:36.399 --> 01:28:40.880
<v Speaker 2>purpose of a speech processor and a transit transceiver? Increase

1359
01:28:40.960 --> 01:28:46.239
<v Speaker 2>that loudness? Introduce that increase. It's going to be a

1360
01:28:46.399 --> 01:28:48.880
<v Speaker 2>increase the loudness of your transmitted voice signal to the

1361
01:28:48.960 --> 01:28:52.600
<v Speaker 2>other guy. How does a speech processor affect a single

1362
01:28:52.720 --> 01:29:01.319
<v Speaker 2>sideband phone signal? Preass average power? Do not peak power,

1363
01:29:01.359 --> 01:29:05.640
<v Speaker 2>but average power? That's the difference. What is the effect

1364
01:29:05.720 --> 01:29:10.319
<v Speaker 2>of an incorrectly adjusted speech processor all those Yeah, there's

1365
01:29:10.319 --> 01:29:15.239
<v Speaker 2>stormed speech excess in their modulation. A lot of people

1366
01:29:15.760 --> 01:29:21.520
<v Speaker 2>have problems with these digital modes, not adjusting their ALC

1367
01:29:21.720 --> 01:29:23.880
<v Speaker 2>in some of these circuits, and you can really see

1368
01:29:23.920 --> 01:29:27.680
<v Speaker 2>it on a digital mode can cause problem if you

1369
01:29:27.800 --> 01:29:33.279
<v Speaker 2>overdrive it. What frequency range is occupied by a three

1370
01:29:33.359 --> 01:29:37.039
<v Speaker 2>killer hurts lower sideband signal? When the carrier displayed is

1371
01:29:37.159 --> 01:29:42.279
<v Speaker 2>seven point one seven eight, it's going to be seven

1372
01:29:42.279 --> 01:29:44.800
<v Speaker 2>point one seventy five. Right, it's three killer hurts below

1373
01:29:44.840 --> 01:29:49.840
<v Speaker 2>because it's a lower side band. Let's see it tells

1374
01:29:49.920 --> 01:29:52.000
<v Speaker 2>us how to do it. Here we subtract three killer

1375
01:29:52.039 --> 01:29:53.880
<v Speaker 2>hurts from that and we get seven point one to

1376
01:29:53.960 --> 01:29:58.520
<v Speaker 2>seventy five. All right, What frequency range is occupated by

1377
01:29:58.560 --> 01:30:03.600
<v Speaker 2>a three killer hurts signal display with the upper sideband signal. Now,

1378
01:30:03.720 --> 01:30:08.199
<v Speaker 2>so we're going to add so three point three four

1379
01:30:08.520 --> 01:30:11.279
<v Speaker 2>would be B three point three four seven and three

1380
01:30:11.319 --> 01:30:14.680
<v Speaker 2>point three five because we're adding three kill hurts to it.

1381
01:30:16.520 --> 01:30:18.760
<v Speaker 2>And how close to the lower edge of a band's

1382
01:30:18.800 --> 01:30:22.439
<v Speaker 2>phone segment should your display care frequency be with three

1383
01:30:22.600 --> 01:30:28.359
<v Speaker 2>killer hurts wide lower sideband? Okay, at least three killer

1384
01:30:28.479 --> 01:30:31.640
<v Speaker 2>hurts on lower sideband. It means you need to be

1385
01:30:31.720 --> 01:30:36.119
<v Speaker 2>above at least three kill hurts above A. You're not

1386
01:30:36.199 --> 01:30:38.119
<v Speaker 2>at one kill hurts is at least three, so the

1387
01:30:38.199 --> 01:30:40.399
<v Speaker 2>ones are out. It's got be above it's lower, so

1388
01:30:40.680 --> 01:30:43.479
<v Speaker 2>be a BOB and the same thing. If you're on

1389
01:30:43.840 --> 01:30:46.760
<v Speaker 2>using the lower upper sidebands, you need to be below

1390
01:30:47.279 --> 01:30:51.520
<v Speaker 2>three kill hurts below which would be B and which

1391
01:30:51.560 --> 01:30:57.079
<v Speaker 2>are The following describes linear amplifier h our evampire used

1392
01:30:57.159 --> 01:31:01.039
<v Speaker 2>touch damage frequency MULTIPLI B B.

1393
01:31:03.479 --> 01:31:03.640
<v Speaker 1>YEP.

1394
01:31:04.279 --> 01:31:07.920
<v Speaker 2>Amplifier preserves the output and fire which the output preserves

1395
01:31:07.960 --> 01:31:10.680
<v Speaker 2>the input wave form. That's right, you're just taking what

1396
01:31:10.960 --> 01:31:14.479
<v Speaker 2>the AMPHI takes what it's given and transmitted. It preserves it.

1397
01:31:14.560 --> 01:31:20.920
<v Speaker 2>That's what they're talking about. What circuit is used to

1398
01:31:21.039 --> 01:31:25.119
<v Speaker 2>select one of the sidebands from a balance modulator. You

1399
01:31:25.239 --> 01:31:29.840
<v Speaker 2>have upper sideband filter, lower sideband filter. What output is

1400
01:31:29.880 --> 01:31:34.319
<v Speaker 2>produced by a balance modulator? So a balance modulator produces

1401
01:31:34.359 --> 01:31:42.000
<v Speaker 2>a double sideband modulated r D. Which of the following

1402
01:31:42.079 --> 01:31:51.399
<v Speaker 2>is an effect of overmodulation, insufficient audio accessive bandwidth the

1403
01:31:51.520 --> 01:31:55.600
<v Speaker 2>excessive bandwidth. What is meant by the term flat topping

1404
01:31:55.640 --> 01:31:58.600
<v Speaker 2>when referring to an amplitude modulated phone signal?

1405
01:32:00.319 --> 01:32:00.439
<v Speaker 1>Uh?

1406
01:32:01.359 --> 01:32:07.239
<v Speaker 2>Trump probably justice the So it's gonna be C signal

1407
01:32:07.279 --> 01:32:11.199
<v Speaker 2>distortion caused by excessive driver speech level. What is the

1408
01:32:11.279 --> 01:32:15.399
<v Speaker 2>modulation envelope of an AM signal? Bandwidth of the modulated

1409
01:32:15.560 --> 01:32:19.119
<v Speaker 2>modulation envelope, it would have to be a waveform creator

1410
01:32:19.199 --> 01:32:24.119
<v Speaker 2>connecting the peak values of the modulated signals. So what

1411
01:32:24.279 --> 01:32:27.600
<v Speaker 2>is the total bandwidth of an NFM phone transmission having

1412
01:32:27.680 --> 01:32:31.800
<v Speaker 2>five killer hurts deviation and three killer hurts modulation frequency?

1413
01:32:32.319 --> 01:32:33.319
<v Speaker 1>So remember how to do this.

1414
01:32:33.479 --> 01:32:36.760
<v Speaker 2>It's two times that, which would be two times five

1415
01:32:36.840 --> 01:32:42.000
<v Speaker 2>plus three is sixteen. What is the frequency deviation for

1416
01:32:42.079 --> 01:32:44.840
<v Speaker 2>a twelve point two one megas practice modulate oscillator and

1417
01:32:45.039 --> 01:32:50.880
<v Speaker 2>five killer deviation? It's uh, So you're gonna divide, You're

1418
01:32:50.880 --> 01:32:54.399
<v Speaker 2>gonna get about you got to divide by twelve, so

1419
01:32:54.479 --> 01:32:58.159
<v Speaker 2>you're gonna get four hundred and sixteen point seven. Hurts me.

1420
01:33:01.199 --> 01:33:05.760
<v Speaker 2>They're gonna talk about amplifiers. Radio operators HF sometimes use

1421
01:33:05.800 --> 01:33:08.600
<v Speaker 2>amplifiers to boost their signals when conditions are poor to

1422
01:33:08.640 --> 01:33:11.520
<v Speaker 2>accommodate difficult propagation paths.

1423
01:33:12.760 --> 01:33:13.359
<v Speaker 1>On HF.

1424
01:33:13.600 --> 01:33:17.079
<v Speaker 2>High power amplifiers often use vacuum pum circuits that require

1425
01:33:17.159 --> 01:33:21.119
<v Speaker 2>operator adjustment. The efficiency of an amplifier is defined as

1426
01:33:21.239 --> 01:33:24.680
<v Speaker 2>the RF output power divided by the DC input power,

1427
01:33:27.159 --> 01:33:32.920
<v Speaker 2>also called linears. A Class A amplifier the most linear,

1428
01:33:33.279 --> 01:33:38.319
<v Speaker 2>lowest cost signal distortion, at least efficient because class as

1429
01:33:38.399 --> 01:33:41.760
<v Speaker 2>passed the entire sinusoil input signal they conduct one hundred

1430
01:33:41.760 --> 01:33:46.159
<v Speaker 2>percent of the time, so Class A good amplifier but

1431
01:33:46.359 --> 01:33:50.239
<v Speaker 2>least efficient. Class B is known as a push pool amplifier,

1432
01:33:51.359 --> 01:33:54.720
<v Speaker 2>and it's a pair of amplifying devices, each actively active,

1433
01:33:54.800 --> 01:33:59.479
<v Speaker 2>gearing complementary halves of the signals cycle. They have good

1434
01:33:59.560 --> 01:34:06.000
<v Speaker 2>linear good efficiency. Class AB midway between the A and

1435
01:34:06.119 --> 01:34:09.159
<v Speaker 2>B LINEARY is not as good, but efficiency is better,

1436
01:34:10.359 --> 01:34:13.000
<v Speaker 2>and Class C has the highest efficiency, but it's only

1437
01:34:13.039 --> 01:34:16.600
<v Speaker 2>suitable for C W and FM due to poor linearity.

1438
01:34:17.319 --> 01:34:24.960
<v Speaker 2>High efficiency, poor linearity Some leary amplifiers can be operated

1439
01:34:25.000 --> 01:34:28.000
<v Speaker 2>in either Class A B for single sideband operation or

1440
01:34:28.079 --> 01:34:32.600
<v Speaker 2>Class C for C c W. Transceivers often include a

1441
01:34:32.680 --> 01:34:35.479
<v Speaker 2>delay in the king circuit timing so that the changeover

1442
01:34:35.600 --> 01:34:40.199
<v Speaker 2>relay is completely switched before transceiver is allowed to supply

1443
01:34:40.279 --> 01:34:44.000
<v Speaker 2>in the r F current. This prevents hot switching in

1444
01:34:44.039 --> 01:34:48.520
<v Speaker 2>which amplifier is already supplying RF it can destroy the

1445
01:34:48.640 --> 01:34:50.680
<v Speaker 2>relay or other external devices.

1446
01:34:53.399 --> 01:34:54.039
<v Speaker 1>Very important.

1447
01:34:55.960 --> 01:35:00.880
<v Speaker 2>You want to make sure you're your your you switch

1448
01:35:00.920 --> 01:35:06.199
<v Speaker 2>between transmit and receive where your amplifier is connected before

1449
01:35:06.239 --> 01:35:09.439
<v Speaker 2>you start transmit, is you connect before you start transmitting.

1450
01:35:10.239 --> 01:35:14.800
<v Speaker 2>Tuning and driving vacuum tube at amplifiers, So if you've

1451
01:35:14.840 --> 01:35:16.840
<v Speaker 2>got a vacuum tube amplifier, you want to set the

1452
01:35:16.880 --> 01:35:20.079
<v Speaker 2>band switch to your desired frequency. You want to apply

1453
01:35:20.199 --> 01:35:22.720
<v Speaker 2>the drive power to the amplifier while adjusting the tune

1454
01:35:22.800 --> 01:35:25.159
<v Speaker 2>control to obtain minimum plate current. Find you got to

1455
01:35:25.199 --> 01:35:28.880
<v Speaker 2>dip it. You got to dip your plate current. Adjust

1456
01:35:28.960 --> 01:35:32.199
<v Speaker 2>the load then to get the peak power output, and

1457
01:35:32.479 --> 01:35:38.119
<v Speaker 2>continual adjusting until the max power is obtained avoid exceeding

1458
01:35:38.159 --> 01:35:39.039
<v Speaker 2>the maxplate current.

1459
01:35:39.680 --> 01:35:39.800
<v Speaker 1>UH.

1460
01:35:40.600 --> 01:35:42.239
<v Speaker 2>The input power to the amp fire may also be

1461
01:35:42.319 --> 01:35:47.840
<v Speaker 2>adjusted during the process. Tubes can be destroyed by applying

1462
01:35:47.880 --> 01:35:54.359
<v Speaker 2>too much drive. Modern amplifiers have protective circuits. Similar cautions

1463
01:35:54.399 --> 01:35:57.800
<v Speaker 2>apply to solid amplifiers with power transistors that can be

1464
01:35:57.880 --> 01:36:01.560
<v Speaker 2>destroyed with successive power. You've got to be careful that

1465
01:36:01.840 --> 01:36:06.760
<v Speaker 2>the controls are pretty good these days protecting them. Some

1466
01:36:06.920 --> 01:36:10.279
<v Speaker 2>amplifiers generate automatic level control signals that can be connected

1467
01:36:10.359 --> 01:36:14.199
<v Speaker 2>back to the transmitter to limit excess drive. Check both

1468
01:36:14.239 --> 01:36:16.920
<v Speaker 2>the amplifier and the transceiver manuals to be sure that

1469
01:36:16.960 --> 01:36:19.800
<v Speaker 2>they're compatible signals. So you know how to use the

1470
01:36:19.840 --> 01:36:23.600
<v Speaker 2>ALC meter readings, so that that's important. It's pretty standard,

1471
01:36:23.640 --> 01:36:25.319
<v Speaker 2>but you need that. Sometimes there's a nuance there. You

1472
01:36:25.359 --> 01:36:30.199
<v Speaker 2>got to go check that out. So neutralization HF amplifiers

1473
01:36:30.239 --> 01:36:33.520
<v Speaker 2>can self oscillate because of positive feedback, and an amplifier too.

1474
01:36:34.920 --> 01:36:39.479
<v Speaker 2>Self oscillation create spurs outputs. You may damage the tube

1475
01:36:39.560 --> 01:36:45.159
<v Speaker 2>or even the amplifier amplifier components. So the technique to

1476
01:36:45.199 --> 01:36:48.399
<v Speaker 2>prevent this is called neutralization. It's done by creating a

1477
01:36:48.479 --> 01:36:52.439
<v Speaker 2>negative feedback, sometimes a small capacitor between the amplifier output

1478
01:36:52.560 --> 01:36:55.159
<v Speaker 2>and the input circuits, and that's usually built into your

1479
01:36:56.159 --> 01:36:58.079
<v Speaker 2>to your amplifier that they've taken care of that, but

1480
01:36:58.119 --> 01:37:00.359
<v Speaker 2>if you're building your own that's an important that you

1481
01:37:00.439 --> 01:37:05.880
<v Speaker 2>need to have in there. Okay, well, what's the effective

1482
01:37:05.960 --> 01:37:09.079
<v Speaker 2>for plate current of the of the correct setting of

1483
01:37:09.119 --> 01:37:12.479
<v Speaker 2>a vacuum two r F power amplifier's tune control? What's

1484
01:37:12.560 --> 01:37:19.960
<v Speaker 2>the EFFECTA of the plate current UH produced to find

1485
01:37:20.000 --> 01:37:20.840
<v Speaker 2>that dip when.

1486
01:37:20.720 --> 01:37:21.159
<v Speaker 1>You're doing it?

1487
01:37:22.640 --> 01:37:24.640
<v Speaker 2>What's the reason to use ALC with an arm of

1488
01:37:24.680 --> 01:37:33.520
<v Speaker 2>amplifier to produce to prevent excessive drive? See? What is

1489
01:37:33.600 --> 01:37:36.720
<v Speaker 2>the current adjustment for the load or what's the correct

1490
01:37:36.760 --> 01:37:39.439
<v Speaker 2>adjustment for the load or coupling control of the vacuum

1491
01:37:39.479 --> 01:37:45.039
<v Speaker 2>tube power amplifier minimum staid you are plate current to

1492
01:37:45.119 --> 01:37:51.560
<v Speaker 2>see ok B, I think let mean d desired power

1493
01:37:51.600 --> 01:37:56.760
<v Speaker 2>output without exceeding the loud maximumiable plate current. So you're

1494
01:37:56.800 --> 01:37:59.840
<v Speaker 2>trying to get those adjustments to load and coupling controls.

1495
01:37:59.880 --> 01:38:02.239
<v Speaker 2>You trying to balance those two to arrive at that.

1496
01:38:04.039 --> 01:38:06.840
<v Speaker 2>What is the purpose of delaying r F output after

1497
01:38:06.920 --> 01:38:12.159
<v Speaker 2>activating a transmitter's keying line to the external amplifier to

1498
01:38:12.239 --> 01:38:15.439
<v Speaker 2>allow time for the amplifier to switch the antenna between

1499
01:38:15.479 --> 01:38:17.279
<v Speaker 2>the transit transceiver.

1500
01:38:16.960 --> 01:38:20.319
<v Speaker 1>And amplifier, so C.

1501
01:38:22.479 --> 01:38:26.279
<v Speaker 2>What's the purpose of a neutralizing and an amplifier to

1502
01:38:26.399 --> 01:38:31.880
<v Speaker 2>limits modulation and then to cut off to eliminate self postellations. B.

1503
01:38:33.520 --> 01:38:36.560
<v Speaker 2>Which of these class of ampfires has the highest efficiency?

1504
01:38:37.960 --> 01:38:42.880
<v Speaker 2>That would be the C class used for FM and

1505
01:38:43.319 --> 01:38:48.119
<v Speaker 2>morse code CW. In a class A amplifier, what percentage

1506
01:38:48.159 --> 01:38:51.399
<v Speaker 2>of the time does the amplifying device conduct Class A?

1507
01:38:51.520 --> 01:38:56.039
<v Speaker 2>It's one hundred MBA. How is the efficiency of an

1508
01:38:56.119 --> 01:39:04.560
<v Speaker 2>RF amplifier determined the d C r F output power

1509
01:39:04.640 --> 01:39:08.479
<v Speaker 2>by the DC input uh? B.

1510
01:39:08.840 --> 01:39:09.399
<v Speaker 1>That's correct.

1511
01:39:11.199 --> 01:39:13.560
<v Speaker 2>Which of the following modes is a class C power

1512
01:39:13.600 --> 01:39:18.760
<v Speaker 2>stage appropriate for amplifying a modulated signal? Following modes is

1513
01:39:18.800 --> 01:39:26.880
<v Speaker 2>a Class C FM only it's not linear, so single

1514
01:39:26.960 --> 01:39:29.439
<v Speaker 2>sideband or AM you have a distortion on those, So

1515
01:39:29.760 --> 01:39:32.760
<v Speaker 2>film all right, our next section, we're gonna be talking

1516
01:39:32.760 --> 01:39:38.479
<v Speaker 2>about receivers and HF station installation. Talk a little about

1517
01:39:38.479 --> 01:39:44.039
<v Speaker 2>superheader superheader dime receivers. UH. Most receivers used by today's

1518
01:39:44.039 --> 01:39:49.600
<v Speaker 2>amateurs are superheader dying UH. The received signals are incredibly

1519
01:39:49.640 --> 01:39:53.239
<v Speaker 2>weak and on the order of nano or peko watts.

1520
01:39:55.199 --> 01:39:57.960
<v Speaker 2>The received signals are first strengthened by an r F amplifier,

1521
01:39:58.039 --> 01:40:02.000
<v Speaker 2>then applied to the r F of a mixer. The

1522
01:40:02.079 --> 01:40:05.119
<v Speaker 2>local oscillator is adjusted so that the desired frequency creates

1523
01:40:05.159 --> 01:40:08.399
<v Speaker 2>a mixing product at the intermediate. At the intermediate frequency,

1524
01:40:09.960 --> 01:40:14.760
<v Speaker 2>a detector or demodulator stage follows the UH IF the

1525
01:40:14.880 --> 01:40:19.439
<v Speaker 2>IF to recover the moduling information. An input amplifier, gain,

1526
01:40:19.520 --> 01:40:23.279
<v Speaker 2>demodulator stage bandwidth, an input amplifier noise can all affect

1527
01:40:23.640 --> 01:40:30.439
<v Speaker 2>transceiver receiver sensitivity. So the receiver's sensitivity to repeat that

1528
01:40:32.319 --> 01:40:36.920
<v Speaker 2>can be impacted by the amplifier, gain, demodulator stage bandwidth,

1529
01:40:37.399 --> 01:40:41.439
<v Speaker 2>an input amplifier noise. All those together and how you've

1530
01:40:41.479 --> 01:40:46.640
<v Speaker 2>got those set up can affect your receiver's instinctivity. Superheaded

1531
01:40:46.760 --> 01:40:50.239
<v Speaker 2>superheaded nine receiver convert signals to audio and two steps

1532
01:40:51.119 --> 01:40:55.399
<v Speaker 2>the front end right here converts the frequency of the

1533
01:40:55.439 --> 01:40:59.479
<v Speaker 2>signal to an intermediate frequency where most of the gain

1534
01:40:59.560 --> 01:41:03.880
<v Speaker 2>of the receiver where the receiver is provided, A second

1535
01:41:03.960 --> 01:41:11.039
<v Speaker 2>mixer is provided, a second mixer, a second mixer. The

1536
01:41:11.279 --> 01:41:14.279
<v Speaker 2>product detector converts the signal to an audio frequency. So

1537
01:41:14.359 --> 01:41:17.000
<v Speaker 2>you come in here on the front end IF filter

1538
01:41:17.199 --> 01:41:21.600
<v Speaker 2>and another IF amplifier, product detector. Audio comes out here

1539
01:41:21.720 --> 01:41:24.720
<v Speaker 2>on audio amp stage. So you've got two osc layers

1540
01:41:24.760 --> 01:41:27.560
<v Speaker 2>of that's called a beat beat local lost lador in

1541
01:41:27.680 --> 01:41:32.079
<v Speaker 2>a BFO, so it's a two stage conversion superhead dyne.

1542
01:41:35.119 --> 01:41:38.479
<v Speaker 2>Once amplified to a more usable level. Single sideband and

1543
01:41:38.520 --> 01:41:42.199
<v Speaker 2>CW signals are demodulated by a product detector. It's a

1544
01:41:42.319 --> 01:41:45.600
<v Speaker 2>special type of mixer. If an AM signal is being received,

1545
01:41:45.680 --> 01:41:49.840
<v Speaker 2>a product detector or envelope detector recovers the modulating signal.

1546
01:41:51.279 --> 01:41:54.000
<v Speaker 2>Output of the detector is an audio signal amplified by

1547
01:41:54.039 --> 01:41:58.319
<v Speaker 2>the audio frequency amplifier and input to a speaker, headphones,

1548
01:41:58.439 --> 01:42:02.920
<v Speaker 2>or a sound card. The r F amplifier mixer are

1549
01:42:03.000 --> 01:42:08.039
<v Speaker 2>the receivers at The RF amplifier and mixer are the

1550
01:42:08.119 --> 01:42:13.239
<v Speaker 2>receiver's front end. It processes weak signals at the original

1551
01:42:13.439 --> 01:42:17.439
<v Speaker 2>frequencies UH. A pre selector is often used to reject

1552
01:42:17.520 --> 01:42:21.439
<v Speaker 2>out of band signals. A pre amplifier or preamp we

1553
01:42:21.520 --> 01:42:24.640
<v Speaker 2>call it is used if additional sensitivity is needed, such

1554
01:42:24.680 --> 01:42:30.520
<v Speaker 2>as weak signals. The simplest possible superhead consists of a

1555
01:42:30.680 --> 01:42:34.760
<v Speaker 2>mixer connected to the antenna, an oscillator to act as

1556
01:42:34.800 --> 01:42:38.520
<v Speaker 2>a local oscillator, and a detector that operates directly on

1557
01:42:38.640 --> 01:42:44.319
<v Speaker 2>the resulting IF signal. The single frequency IF stage makes

1558
01:42:44.399 --> 01:42:46.760
<v Speaker 2>it much user to create high quality filters and high

1559
01:42:46.800 --> 01:42:48.720
<v Speaker 2>gain amplifiers without having.

1560
01:42:48.520 --> 01:42:49.119
<v Speaker 1>To be tuned.

1561
01:42:49.880 --> 01:42:51.720
<v Speaker 2>Only the lo O needs to be tuned in the

1562
01:42:51.800 --> 01:42:59.079
<v Speaker 2>superhead receiver. Recall the formula for intermodulation mixing of signals.

1563
01:42:59.399 --> 01:43:03.199
<v Speaker 2>You get F one plus F two. For example, to

1564
01:43:03.279 --> 01:43:07.039
<v Speaker 2>convert an RF signal on one twenty five megahertz to

1565
01:43:07.159 --> 01:43:10.720
<v Speaker 2>an IF of four to fifty five, the lo O

1566
01:43:10.880 --> 01:43:13.760
<v Speaker 2>must be tuned to either four point twenty five minus

1567
01:43:13.800 --> 01:43:16.560
<v Speaker 2>four fifty five, which is equal to thirteen point seven

1568
01:43:16.680 --> 01:43:20.600
<v Speaker 2>nine five, or to fourteen point twenty five plus four

1569
01:43:20.640 --> 01:43:23.520
<v Speaker 2>to fifty five, which is equal to fourteen point seven

1570
01:43:23.600 --> 01:43:30.359
<v Speaker 2>oh five. Superheterodynes have some weaknesses, like all radio designs,

1571
01:43:31.000 --> 01:43:33.039
<v Speaker 2>because they are mixing products at both the some and

1572
01:43:33.119 --> 01:43:37.399
<v Speaker 2>difference frequencies. Undesired signals can create their own mixing products

1573
01:43:37.439 --> 01:43:44.520
<v Speaker 2>at the IF uh so we've got got the RF

1574
01:43:44.560 --> 01:43:47.720
<v Speaker 2>input local oscillator, we get the sum and the differences

1575
01:43:47.800 --> 01:43:53.279
<v Speaker 2>of these two. Another flaw is caused by the local

1576
01:43:53.319 --> 01:43:56.960
<v Speaker 2>oscilator and other oscillator circuits. Leakage of signals into the

1577
01:43:57.000 --> 01:43:59.840
<v Speaker 2>signal path can cause steady state signals to appear. Called

1578
01:44:02.319 --> 01:44:06.359
<v Speaker 2>a figure because the next figure shows a single conversion

1579
01:44:06.560 --> 01:44:09.399
<v Speaker 2>with only one mixer converting the signal from the IF

1580
01:44:09.560 --> 01:44:12.880
<v Speaker 2>to the RF. This is the single conversion right here

1581
01:44:16.640 --> 01:44:23.840
<v Speaker 2>r F input one oscillator down single conversion. The IF

1582
01:44:23.920 --> 01:44:26.760
<v Speaker 2>stage provides most of the high gain most of the

1583
01:44:26.840 --> 01:44:31.640
<v Speaker 2>game in selectivity. Filtering is applied at each IF allows

1584
01:44:31.720 --> 01:44:35.520
<v Speaker 2>filter bandwidth selection for the desired signal. This gives the

1585
01:44:35.600 --> 01:44:39.279
<v Speaker 2>best received signal quality with the lowest unwanted noise and interference,

1586
01:44:39.439 --> 01:44:43.319
<v Speaker 2>maximizing the signal to noise ratio. In a mixture with

1587
01:44:43.439 --> 01:44:46.239
<v Speaker 2>an r F input or input frequency F one and

1588
01:44:46.319 --> 01:44:49.520
<v Speaker 2>local loss or F two, remember there are mixing products

1589
01:44:49.600 --> 01:44:52.399
<v Speaker 2>that f one plus or minus f two, meaning the

1590
01:44:52.520 --> 01:44:55.680
<v Speaker 2>sum and the difference of the two. When an L

1591
01:44:56.520 --> 01:44:59.199
<v Speaker 2>with an LO of thirteen point eight megahertz, a mixing

1592
01:44:59.279 --> 01:45:02.119
<v Speaker 2>product of fore fifty five killerhertzer point four to five

1593
01:45:02.239 --> 01:45:05.520
<v Speaker 2>five can be generated by a signal of either fourteen

1594
01:45:05.600 --> 01:45:09.079
<v Speaker 2>point two five five or thirteen point three four five,

1595
01:45:09.880 --> 01:45:12.479
<v Speaker 2>assuming that the intended signal is fourteen point twenty five

1596
01:45:12.479 --> 01:45:17.560
<v Speaker 2>to five meg hurts. An image response is an image

1597
01:45:17.600 --> 01:45:24.600
<v Speaker 2>response similar to AM single sideband and CW superhits. The

1598
01:45:24.720 --> 01:45:31.000
<v Speaker 2>linear IF amplifiers replaced by a limited limited amplifiers limited amplifiers.

1599
01:45:31.039 --> 01:45:35.680
<v Speaker 2>The received signal until all amplified modulated information noise is

1600
01:45:35.760 --> 01:45:39.199
<v Speaker 2>removed and only a square wave of the of the

1601
01:45:39.319 --> 01:45:43.720
<v Speaker 2>varying frequency remains. AUTO information is recovered by a discriminator

1602
01:45:43.840 --> 01:45:49.800
<v Speaker 2>or quadrator detector that replaces the product detector. Once the

1603
01:45:49.960 --> 01:45:54.159
<v Speaker 2>FIM signal is converted to the IF high gain amplifiers

1604
01:45:54.199 --> 01:45:56.680
<v Speaker 2>called limitters change the signal to a square wave that

1605
01:45:56.880 --> 01:46:01.199
<v Speaker 2>only varies in frequency, not amplitude, a discriminator converts the

1606
01:46:01.279 --> 01:46:06.760
<v Speaker 2>frequency variations to audio. So here's a block diagram of

1607
01:46:06.840 --> 01:46:14.520
<v Speaker 2>an FM signal amplifier, mixer I F filter limiter, discriminator,

1608
01:46:14.840 --> 01:46:24.079
<v Speaker 2>and then the audio amplifier itself. For digital signal processing,

1609
01:46:24.159 --> 01:46:27.119
<v Speaker 2>the general term which is a general term for converting

1610
01:46:27.159 --> 01:46:33.039
<v Speaker 2>signals from analog to digital. A DSP system uses an

1611
01:46:33.039 --> 01:46:36.479
<v Speaker 2>analog to digital converter change the signal to a digital data.

1612
01:46:37.279 --> 01:46:41.159
<v Speaker 2>A special type of microprocessor then performs the mathematical operations

1613
01:46:41.199 --> 01:46:45.159
<v Speaker 2>on the data to accomplish filtering, noise reduction, and other functions.

1614
01:46:45.640 --> 01:46:49.720
<v Speaker 2>A digital to analog converter changes the process data back

1615
01:46:49.760 --> 01:46:53.600
<v Speaker 2>to analog form for an audio for to output as

1616
01:46:54.000 --> 01:47:05.560
<v Speaker 2>as audio. Digital signal processing has two advantages over analog circuitry. Performance, flexibility,

1617
01:47:06.399 --> 01:47:10.359
<v Speaker 2>UH DSP offers selectable programmable filters and allow the operator

1618
01:47:10.399 --> 01:47:13.239
<v Speaker 2>to adjust the filter bandwidth and shape, even in shape,

1619
01:47:13.279 --> 01:47:17.560
<v Speaker 2>and even to define new filters. Expensive functions and analog

1620
01:47:17.640 --> 01:47:20.000
<v Speaker 2>circuits can be implemented in DSP as a as a

1621
01:47:20.079 --> 01:47:24.439
<v Speaker 2>program without additional hardware. Just a lot of the modern

1622
01:47:24.520 --> 01:47:27.960
<v Speaker 2>receivers today at radios we buy have DSP circuits in

1623
01:47:28.079 --> 01:47:30.800
<v Speaker 2>them UH and they've come a long way and they

1624
01:47:30.880 --> 01:47:31.840
<v Speaker 2>work very well.

1625
01:47:33.760 --> 01:47:36.800
<v Speaker 1>To manage the the receiver gain or r F gain.

1626
01:47:38.159 --> 01:47:40.840
<v Speaker 2>Looking for weak signals, set RF gain to its maximum

1627
01:47:41.000 --> 01:47:44.960
<v Speaker 2>for highest receiver sensitivity, lower r F gain volume to

1628
01:47:45.000 --> 01:47:51.520
<v Speaker 2>reduce background noise. Automatic gain control AGC circuits very gain

1629
01:47:51.600 --> 01:47:53.640
<v Speaker 2>of the r r F and I have amplifiers, so

1630
01:47:53.760 --> 01:47:57.079
<v Speaker 2>output volume stays constant for both weak and strong signals.

1631
01:47:57.960 --> 01:48:02.680
<v Speaker 2>AGC circuits changes the voltage that controls the IF gain m.

1632
01:48:03.159 --> 01:48:05.760
<v Speaker 2>This voltage is read by the S meter, which measures

1633
01:48:05.800 --> 01:48:13.039
<v Speaker 2>signal strength. S meters are calibrated in S units, so

1634
01:48:13.439 --> 01:48:17.760
<v Speaker 2>one S unit equals up to six dB. Four fold

1635
01:48:17.880 --> 01:48:22.119
<v Speaker 2>is equal to four x change in signal strength S nine.

1636
01:48:22.239 --> 01:48:26.239
<v Speaker 2>A strong signal is located at the midpoint of the display.

1637
01:48:27.439 --> 01:48:30.720
<v Speaker 2>Large values to the right twenty forty and sixty. These

1638
01:48:30.760 --> 01:48:35.279
<v Speaker 2>correspond to dB above S nine. Readings of S nine

1639
01:48:35.319 --> 01:48:38.359
<v Speaker 2>plus twenty dB is a signal twenty dB or one

1640
01:48:38.439 --> 01:48:44.640
<v Speaker 2>hundred times stronger than an S nine signal. Receiver linearity,

1641
01:48:45.880 --> 01:48:49.399
<v Speaker 2>and if the received signal is distorted, spurry signals will

1642
01:48:49.439 --> 01:48:53.359
<v Speaker 2>appear just as if transmitting stations were emitting them. The

1643
01:48:53.439 --> 01:48:57.399
<v Speaker 2>most common form of receiver non linearity is overload, also

1644
01:48:57.520 --> 01:49:02.439
<v Speaker 2>code called front end overload or gain COMPRESSIH. The solution

1645
01:49:02.800 --> 01:49:05.359
<v Speaker 2>to overload is to filter out the fending signal or

1646
01:49:05.439 --> 01:49:09.600
<v Speaker 2>reduce receiver game. It's an attenuator circuit. Proper use of

1647
01:49:09.640 --> 01:49:13.439
<v Speaker 2>attenuator and RF GAG controls can dramatically reduce received noise

1648
01:49:13.520 --> 01:49:16.680
<v Speaker 2>distortion caused by strong signals. So again, a lot of

1649
01:49:16.720 --> 01:49:20.000
<v Speaker 2>our modern amplifiers have some pretty good controls for these

1650
01:49:20.119 --> 01:49:23.800
<v Speaker 2>kinds of things, and if you learn how to use them,

1651
01:49:23.920 --> 01:49:30.239
<v Speaker 2>and you can really help improve your receiver receiver reception. So,

1652
01:49:31.079 --> 01:49:32.960
<v Speaker 2>you know, get out your man you'll look at those controls.

1653
01:49:33.000 --> 01:49:34.720
<v Speaker 2>A lot of folks, you know, we buy these radios,

1654
01:49:34.760 --> 01:49:36.520
<v Speaker 2>have all these cool features and we want to use

1655
01:49:36.520 --> 01:49:38.560
<v Speaker 2>a few of them. But look at your manual. There's

1656
01:49:38.600 --> 01:49:40.640
<v Speaker 2>some really cool things will allow you to really fine

1657
01:49:40.680 --> 01:49:45.640
<v Speaker 2>tune and get your receiver working great. I have filters

1658
01:49:47.640 --> 01:49:50.439
<v Speaker 2>narrow the receiver's pass man They get rid of the

1659
01:49:50.640 --> 01:49:54.520
<v Speaker 2>unwanted signals. Notch filters remove signals and a very narrow

1660
01:49:54.640 --> 01:49:57.840
<v Speaker 2>bandwidth the frequency such as signal tone from an interfering carrier.

1661
01:49:59.279 --> 01:50:01.319
<v Speaker 2>A lot of these, the newer ones and the dogs

1662
01:50:01.359 --> 01:50:03.520
<v Speaker 2>filters are great. They're they're usually it's some kind of

1663
01:50:03.560 --> 01:50:07.600
<v Speaker 2>a digital form now and uh uh they work, they work,

1664
01:50:07.680 --> 01:50:09.920
<v Speaker 2>they work well, so you know, get your manual out,

1665
01:50:09.960 --> 01:50:12.439
<v Speaker 2>figure out how to use this stuff. There's really neat

1666
01:50:12.520 --> 01:50:13.039
<v Speaker 2>things in these.

1667
01:50:13.760 --> 01:50:13.880
<v Speaker 1>Uh.

1668
01:50:14.520 --> 01:50:18.079
<v Speaker 2>On the pass band or if ship adjust receivers passband

1669
01:50:18.119 --> 01:50:21.159
<v Speaker 2>above and below the displayed carrier frequency. So if you've

1670
01:50:21.159 --> 01:50:23.039
<v Speaker 2>got some noise on the if you're on a single

1671
01:50:23.119 --> 01:50:25.199
<v Speaker 2>side of band and have some crash over here noise,

1672
01:50:25.399 --> 01:50:27.199
<v Speaker 2>you can sometimes take that, just move it a little

1673
01:50:27.199 --> 01:50:29.000
<v Speaker 2>bit and get that out of your way.

1674
01:50:29.319 --> 01:50:29.439
<v Speaker 1>Uh.

1675
01:50:30.119 --> 01:50:32.520
<v Speaker 2>And also allowed it keeps you from interfering with the

1676
01:50:32.600 --> 01:50:37.520
<v Speaker 2>other folks. Reverse sideband controls allow switching between received c

1677
01:50:37.760 --> 01:50:42.920
<v Speaker 2>W signals above carrier frequency LSB and below USB and LSB.

1678
01:50:43.800 --> 01:50:46.760
<v Speaker 2>There's some boids interference by placing the signals on the

1679
01:50:46.840 --> 01:50:50.880
<v Speaker 2>other side of the carrier where filtering rejects, So that's

1680
01:50:50.880 --> 01:50:52.159
<v Speaker 2>another technique you can use.

1681
01:50:53.880 --> 01:50:54.000
<v Speaker 1>Uh.

1682
01:50:54.439 --> 01:50:59.760
<v Speaker 2>Some other ways to reduce noise. Noise noise blinkers uh uh.

1683
01:51:00.119 --> 01:51:02.920
<v Speaker 2>They can sense sharp short sharp pulses and the IF

1684
01:51:02.960 --> 01:51:05.319
<v Speaker 2>signal and reduce the gain of the IF and audio

1685
01:51:05.920 --> 01:51:10.039
<v Speaker 2>amplifiers during the pulse. It's called blanking. Adjust your noise.

1686
01:51:10.079 --> 01:51:12.640
<v Speaker 2>Blankers can be set to blank to receive at different

1687
01:51:12.680 --> 01:51:14.399
<v Speaker 2>noise levels, so you have to play around with that.

1688
01:51:15.800 --> 01:51:18.760
<v Speaker 2>They do work. If you have some periodic noise that's

1689
01:51:18.840 --> 01:51:20.479
<v Speaker 2>going on, you can cut that in.

1690
01:51:20.640 --> 01:51:21.439
<v Speaker 1>It works pretty good.

1691
01:51:23.640 --> 01:51:26.479
<v Speaker 2>Noise reduction is performed by the digital signal processors. They

1692
01:51:26.520 --> 01:51:28.560
<v Speaker 2>can remove hiss and noise from the audio that is

1693
01:51:28.600 --> 01:51:32.399
<v Speaker 2>not part of of the desired speech CW. Increasing the

1694
01:51:32.439 --> 01:51:34.720
<v Speaker 2>noise reduction level may cause some of the desired signal

1695
01:51:34.800 --> 01:51:38.720
<v Speaker 2>to be removed, causing distortion. So use the least amount

1696
01:51:38.800 --> 01:51:42.199
<v Speaker 2>when you needed to minimize. You're still intelligibly hear what

1697
01:51:42.279 --> 01:51:44.239
<v Speaker 2>you're trying to hear, so there's a trade off there.

1698
01:51:44.319 --> 01:51:47.720
<v Speaker 2>But they do work fairly well too. And the DSP

1699
01:51:47.840 --> 01:51:50.560
<v Speaker 2>noise reductions have been around for a while and they

1700
01:51:50.640 --> 01:51:55.760
<v Speaker 2>work pretty well. Okay, what's the purpose? Not the notch

1701
01:51:55.840 --> 01:52:03.520
<v Speaker 2>filter found in many HF transceivers to reduce interference carriers in.

1702
01:52:03.520 --> 01:52:04.159
<v Speaker 1>The past band.

1703
01:52:04.680 --> 01:52:08.000
<v Speaker 2>I think that's what is b What is an advantage

1704
01:52:08.000 --> 01:52:11.319
<v Speaker 2>of selecting the opposite or reverse sideband when receiving CW.

1705
01:52:16.239 --> 01:52:19.319
<v Speaker 2>I think C maybe possible reduce eliminate interference from the

1706
01:52:19.319 --> 01:52:25.239
<v Speaker 2>other signals. How does a noise blanker work increases bandwidth? Nope,

1707
01:52:25.359 --> 01:52:28.560
<v Speaker 2>redrects noise points, Nope, reduces gain during the noise pulse.

1708
01:52:29.560 --> 01:52:33.239
<v Speaker 2>Uh C, it's actually reducing the game during the noise

1709
01:52:33.359 --> 01:52:37.720
<v Speaker 2>the noise pulses. What happens as a receiver's noise reduction

1710
01:52:37.880 --> 01:52:45.079
<v Speaker 2>level is increased, received signals may become distorted. I think

1711
01:52:45.119 --> 01:52:49.239
<v Speaker 2>that's what we just said. A. What's the purpose of

1712
01:52:49.720 --> 01:52:57.880
<v Speaker 2>using a received attenuation receive attenuator? A's good one, are.

1713
01:53:01.439 --> 01:53:01.560
<v Speaker 1>There?

1714
01:53:02.439 --> 01:53:06.279
<v Speaker 2>Well, we'd have to be a event receiver overload from

1715
01:53:06.279 --> 01:53:10.359
<v Speaker 2>strong incoming signals. All right, What does an S meter

1716
01:53:10.479 --> 01:53:17.159
<v Speaker 2>measure measures that received signal strength? How does a signal

1717
01:53:17.199 --> 01:53:20.119
<v Speaker 2>that that reads twenty dB over S nine compared to

1718
01:53:20.159 --> 01:53:23.439
<v Speaker 2>one that reads S nine on the receiver assume a

1719
01:53:23.520 --> 01:53:28.199
<v Speaker 2>properly calibrated S meter. Well, if you recall twenty dB,

1720
01:53:29.600 --> 01:53:31.600
<v Speaker 2>if you did an old math will be one hundred times,

1721
01:53:31.680 --> 01:53:37.800
<v Speaker 2>so it's one hundred times more powerful. D how much

1722
01:53:37.920 --> 01:53:40.920
<v Speaker 2>change in a signal strength is typically represented.

1723
01:53:40.359 --> 01:53:43.279
<v Speaker 1>By one S unit? Okay?

1724
01:53:45.760 --> 01:53:48.560
<v Speaker 2>How much must the power output of a transmitter be

1725
01:53:48.800 --> 01:53:52.239
<v Speaker 2>raised to change the S meter reading on a distant

1726
01:53:52.279 --> 01:53:54.560
<v Speaker 2>receiver from S to S eight to S nine?

1727
01:53:54.600 --> 01:53:54.880
<v Speaker 1>Okay?

1728
01:53:55.000 --> 01:54:00.239
<v Speaker 2>So so remember we got we just talked about just

1729
01:54:00.520 --> 01:54:05.039
<v Speaker 2>units six dB, So if I go six dB, what's

1730
01:54:05.119 --> 01:54:07.720
<v Speaker 2>that power? How much power increase did I have? Remember

1731
01:54:07.760 --> 01:54:12.239
<v Speaker 2>it's three dB is two times, so that's six dvs

1732
01:54:12.239 --> 01:54:14.239
<v Speaker 2>so probably four times. So we'll see if it's c

1733
01:54:14.680 --> 01:54:21.760
<v Speaker 2>that's the right answer. How's a product detector used? It's

1734
01:54:21.840 --> 01:54:30.119
<v Speaker 2>a if A receiver to perform frequency h D using

1735
01:54:30.159 --> 01:54:32.479
<v Speaker 2>a single sideban receiver to extract the modulated signal.

1736
01:54:32.560 --> 01:54:33.079
<v Speaker 1>That's correct.

1737
01:54:33.840 --> 01:54:35.880
<v Speaker 2>Which of the following is an advantage of a digital

1738
01:54:35.960 --> 01:54:41.359
<v Speaker 2>signal processor? A filter compared to an analog filter as

1739
01:54:41.399 --> 01:54:47.720
<v Speaker 2>good fewer digital comment? Yeah, A. You can do a

1740
01:54:47.800 --> 01:54:51.119
<v Speaker 2>wide range of things with a DSP filter, different shapes,

1741
01:54:51.119 --> 01:54:55.920
<v Speaker 2>different sizes. You can create things which parameter affects receiver sensitivity.

1742
01:54:56.520 --> 01:55:00.720
<v Speaker 2>All three of those things, the ample fire game, the

1743
01:55:00.800 --> 01:55:05.239
<v Speaker 2>demodulator stage, and the noise figure. All those d which

1744
01:55:05.279 --> 01:55:08.199
<v Speaker 2>figure input is varied or tuned to convert signals of

1745
01:55:08.239 --> 01:55:13.680
<v Speaker 2>different frequencies to an intermediate frequency that would be the

1746
01:55:13.720 --> 01:55:19.079
<v Speaker 2>low cost leader. What's the term for interference from a

1747
01:55:19.159 --> 01:55:22.399
<v Speaker 2>signal at twice the if frequency from a desired signal?

1748
01:55:24.760 --> 01:55:29.760
<v Speaker 2>That would be image response? Why is it good to

1749
01:55:29.840 --> 01:55:32.920
<v Speaker 2>match receiver bandwidth to the bandwidth of the operating mode?

1750
01:55:35.079 --> 01:55:41.640
<v Speaker 2>I think results the best signal of the noise. Absolutely Okay,

1751
01:55:42.399 --> 01:55:47.520
<v Speaker 2>talk about HF signal HF station installation. HF operating with

1752
01:55:47.640 --> 01:55:51.640
<v Speaker 2>longer wavelengths and higher frequency, higher field strengths makes grounding

1753
01:55:51.680 --> 01:55:54.439
<v Speaker 2>and interference control much more important. Now that you're going

1754
01:55:54.520 --> 01:55:56.760
<v Speaker 2>to be a general and down in the HF a

1755
01:55:56.800 --> 01:55:58.159
<v Speaker 2>little more, do you have to pay a little more

1756
01:55:58.439 --> 01:56:04.039
<v Speaker 2>attention to your HF state installation? The general exam focuses

1757
01:56:04.079 --> 01:56:09.119
<v Speaker 2>on three related areas, mobile installations, RF grounding, and RF interference.

1758
01:56:11.680 --> 01:56:15.239
<v Speaker 2>Mobile radios can produce output of about one hundred wats

1759
01:56:16.119 --> 01:56:19.439
<v Speaker 2>that can output one hundred watch requires solid power connections

1760
01:56:20.439 --> 01:56:25.520
<v Speaker 2>capable of supplying twenty amps or more. Solid state radios

1761
01:56:25.560 --> 01:56:29.920
<v Speaker 2>perform unpredictably with input volted drops below the specified minermum

1762
01:56:30.159 --> 01:56:34.479
<v Speaker 2>power output supply power supply range. Best power connection is

1763
01:56:35.159 --> 01:56:37.840
<v Speaker 2>a direct connection to the battery with heavy gauge wire

1764
01:56:37.960 --> 01:56:43.000
<v Speaker 2>with both of the leads fused. So mobile mobile installation

1765
01:56:43.359 --> 01:56:45.720
<v Speaker 2>connected it in your car, go direct it to your battery.

1766
01:56:45.720 --> 01:56:48.359
<v Speaker 2>If you can use heavy gauge wire, use both the wires.

1767
01:56:50.199 --> 01:56:55.439
<v Speaker 2>Don't use a cigarette lighter or auxiliary circuit socket usually

1768
01:56:55.479 --> 01:56:59.479
<v Speaker 2>greater for just a few ampsh and they're insufficiently insufficient

1769
01:56:59.520 --> 01:57:01.760
<v Speaker 2>to supply the power needed for one hundred watt radio

1770
01:57:03.039 --> 01:57:06.359
<v Speaker 2>UH stalks. If you have an older, older models like

1771
01:57:06.640 --> 01:57:09.199
<v Speaker 2>before the nineteen eighties or so, they were usually a

1772
01:57:09.279 --> 01:57:13.159
<v Speaker 2>little more robust, but the newer ones they've reduced the

1773
01:57:13.199 --> 01:57:22.279
<v Speaker 2>power on the cigarette lighter output. UH all right, hey,

1774
01:57:22.359 --> 01:57:26.520
<v Speaker 2>mobile installations a limited UH limitation of mobile installations is

1775
01:57:26.960 --> 01:57:31.359
<v Speaker 2>electrically short. A smaller in terms of wavelength, antennas are

1776
01:57:31.439 --> 01:57:34.560
<v Speaker 2>less efficient than full sized ones, particularly on the lower

1777
01:57:35.119 --> 01:57:40.079
<v Speaker 2>frequency bands. Some tips to improve the antenna performance UH

1778
01:57:40.359 --> 01:57:42.880
<v Speaker 2>use the most efficient antenna. You can make sure your

1779
01:57:42.920 --> 01:57:46.239
<v Speaker 2>ground connections are solid. Mount the antenna where it's clear

1780
01:57:46.319 --> 01:57:53.960
<v Speaker 2>for metal surfaces. H. Mobile interference different interference sources than

1781
01:57:54.039 --> 01:57:57.920
<v Speaker 2>home stations. UH. When you're when you're when when you're mobile,

1782
01:57:57.960 --> 01:58:01.680
<v Speaker 2>you got the ignition noise uh uh, spark plugs firing.

1783
01:58:02.000 --> 01:58:04.399
<v Speaker 2>You know, if you've got a diesel engine car, A

1784
01:58:04.479 --> 01:58:08.359
<v Speaker 2>lot of things that can cause noise, the alternator, wine,

1785
01:58:09.079 --> 01:58:15.079
<v Speaker 2>your vehicle, accessories, onboard control computers, electric motors, fuel pumps, windows,

1786
01:58:15.479 --> 01:58:19.319
<v Speaker 2>those are all sources of interference. Winches if you have

1787
01:58:19.399 --> 01:58:21.159
<v Speaker 2>a four x four with a winch on the front,

1788
01:58:22.760 --> 01:58:27.520
<v Speaker 2>so just be careful those things. Grounding and bonding AC

1789
01:58:27.680 --> 01:58:32.680
<v Speaker 2>grounding the bench had voltage from appearing on equipment chassis,

1790
01:58:33.039 --> 01:58:37.039
<v Speaker 2>breaking them shock hazard. To manage r F bond equipment

1791
01:58:37.159 --> 01:58:41.479
<v Speaker 2>enclosures together. Bonding means to connect two points together to

1792
01:58:41.560 --> 01:58:48.920
<v Speaker 2>minimize voltage differences between them during digital operation. Unwanted r

1793
01:58:49.000 --> 01:58:53.279
<v Speaker 2>F currents can cause distortion erradic operation of computer interfaces

1794
01:58:53.319 --> 01:58:59.279
<v Speaker 2>and activate transmitters improperly and garble digital protocols, so bonding

1795
01:58:59.319 --> 01:59:02.880
<v Speaker 2>and grounding can help eliminate some of those issues. Here's

1796
01:59:02.880 --> 01:59:06.479
<v Speaker 2>an example of a typical bonding of RF components in

1797
01:59:06.600 --> 01:59:09.720
<v Speaker 2>your shack. That you want to keep all the equipment

1798
01:59:09.760 --> 01:59:14.079
<v Speaker 2>at the same RF, the same RF voltage, the same potential.

1799
01:59:14.800 --> 01:59:18.079
<v Speaker 2>So in this case here he's got a solid copper

1800
01:59:18.159 --> 01:59:21.520
<v Speaker 2>bus short straps between each of the pieces of equipment

1801
01:59:21.760 --> 01:59:24.720
<v Speaker 2>and then you've got a single point ground somewhere. This

1802
01:59:24.880 --> 01:59:26.720
<v Speaker 2>is a good check. This is a good set up.

1803
01:59:27.760 --> 01:59:30.560
<v Speaker 2>I have a similar setup at my station. Been working

1804
01:59:30.720 --> 01:59:33.720
<v Speaker 2>pretty well here lately. So of courks are pretty good.

1805
01:59:36.600 --> 01:59:39.640
<v Speaker 2>Connect all metal equipment enclosures directly together to a common

1806
01:59:39.760 --> 01:59:45.199
<v Speaker 2>RF bonding bus. Keep connections and keep connections straps and

1807
01:59:45.239 --> 01:59:49.600
<v Speaker 2>wire short. You don't want them to be electrically a

1808
01:59:49.680 --> 01:59:51.680
<v Speaker 2>wavelength of something that you're using, or it will be

1809
01:59:51.760 --> 01:59:56.560
<v Speaker 2>a be an antennae, So you short heavy inductors fourteen

1810
01:59:56.640 --> 01:59:59.439
<v Speaker 2>and twelve gage wires or strap strap best.

1811
01:59:59.239 --> 01:59:59.640
<v Speaker 1>If you can.

1812
02:00:00.880 --> 02:00:04.399
<v Speaker 2>If strong RF is present, use a piece of wide

1813
02:00:04.479 --> 02:00:08.760
<v Speaker 2>flashing or screen under the equipment connected to the bonding bus.

1814
02:00:09.000 --> 02:00:12.359
<v Speaker 2>Sometimes that will work. If ground connection is resonant at

1815
02:00:12.399 --> 02:00:18.000
<v Speaker 2>an odd number of quarter wavelengths, it will generate high

1816
02:00:18.000 --> 02:00:21.199
<v Speaker 2>impedants which enables r F voltages or enclosures and cables

1817
02:00:22.079 --> 02:00:26.319
<v Speaker 2>on those devices, So try to avoid, you know, wavelengths

1818
02:00:26.359 --> 02:00:29.880
<v Speaker 2>of of what you're trying to operate on, for g

1819
02:00:29.880 --> 02:00:34.520
<v Speaker 2>links of cables. Ground loops are created by a continuous

1820
02:00:34.560 --> 02:00:38.319
<v Speaker 2>current path around the series of equipment connections. Loop acts.

1821
02:00:38.920 --> 02:00:42.239
<v Speaker 2>Loops acts as a single conductor turn conductor picks up

1822
02:00:42.279 --> 02:00:48.640
<v Speaker 2>voltages from magnetic fields from transformers, et cetera. So you know,

1823
02:00:48.920 --> 02:00:50.720
<v Speaker 2>if you hear if a result, this can result in

1824
02:00:50.800 --> 02:00:53.760
<v Speaker 2>a hum in a transmitted signal. They interference with control

1825
02:00:53.840 --> 02:00:56.960
<v Speaker 2>or data signals. If you see your station operating erradically,

1826
02:00:57.239 --> 02:01:00.359
<v Speaker 2>check for ground loops and those kinds of things. Ground

1827
02:01:00.399 --> 02:01:02.840
<v Speaker 2>loops can be avoided by connecting all the ground conductors

1828
02:01:02.920 --> 02:01:04.760
<v Speaker 2>to an r F bonding bus like we've shown in

1829
02:01:04.840 --> 02:01:08.600
<v Speaker 2>the picture before, just one path. Try to avoid loops

1830
02:01:08.600 --> 02:01:15.319
<v Speaker 2>if you can. Here's some causes and some solutions for

1831
02:01:15.600 --> 02:01:16.000
<v Speaker 2>r if I.

1832
02:01:16.520 --> 02:01:20.239
<v Speaker 1>Uh, you know, some solutions things are like.

1833
02:01:20.760 --> 02:01:24.119
<v Speaker 2>R F chokes. You can put r F chokes on

1834
02:01:24.239 --> 02:01:29.720
<v Speaker 2>wires online. You can put low pass filters on transmitters

1835
02:01:29.880 --> 02:01:31.000
<v Speaker 2>outputs if you have to.

1836
02:01:33.119 --> 02:01:33.640
<v Speaker 1>You know, just.

1837
02:01:35.960 --> 02:01:38.119
<v Speaker 2>Just go through each of these things and try to

1838
02:01:38.640 --> 02:01:41.199
<v Speaker 2>figure out what's going on. Ask you, ask your your

1839
02:01:41.439 --> 02:01:44.159
<v Speaker 2>your your friend who's a ham Maybe they can help

1840
02:01:44.239 --> 02:01:47.239
<v Speaker 2>to But usually if you get your bonding and grounding right,

1841
02:01:47.880 --> 02:01:53.279
<v Speaker 2>you're gonna do pretty good. So radio frequency interference r

1842
02:01:53.279 --> 02:01:59.439
<v Speaker 2>if I. What are some symptoms? It varies. Interference consists

1843
02:01:59.479 --> 02:02:02.359
<v Speaker 2>of on off buzzes or humming or clicks. If you

1844
02:02:02.439 --> 02:02:04.760
<v Speaker 2>hear that when you're operating CW or f M or

1845
02:02:04.840 --> 02:02:13.560
<v Speaker 2>data uh UH equipment, you can direct detection. You'll hear

1846
02:02:14.000 --> 02:02:16.880
<v Speaker 2>I call RF rectification on a speaker or something of you.

1847
02:02:17.039 --> 02:02:19.399
<v Speaker 2>You're you're you're transmitting, but you're hearing us squawking out

1848
02:02:19.439 --> 02:02:23.560
<v Speaker 2>of a speaker in your room. Uh. That can happen UH.

1849
02:02:25.159 --> 02:02:29.640
<v Speaker 2>Single sideband voice similar to AM, but voice sounds garbled

1850
02:02:29.760 --> 02:02:33.560
<v Speaker 2>or distorted. Things you can do to help prevent that

1851
02:02:33.920 --> 02:02:40.720
<v Speaker 2>is UH. You can install some filters. UH. You can

1852
02:02:40.760 --> 02:02:45.960
<v Speaker 2>put chokes or use a fair right core core for

1853
02:02:46.119 --> 02:02:49.840
<v Speaker 2>conductors carrying R current UH to r F choke by

1854
02:02:49.920 --> 02:02:52.439
<v Speaker 2>winding it around through a faire course. You can do

1855
02:02:52.560 --> 02:02:56.720
<v Speaker 2>some things by taking a table uh wire or have

1856
02:02:56.800 --> 02:02:58.600
<v Speaker 2>these clamp on things at work and you sort of

1857
02:02:58.640 --> 02:03:00.600
<v Speaker 2>have to play with them based on what your artified

1858
02:03:00.680 --> 02:03:05.199
<v Speaker 2>interferences all right Beads placed on cables to prevent artf

1859
02:03:05.239 --> 02:03:08.119
<v Speaker 2>common mode from flowing on the outside of the cable

1860
02:03:08.159 --> 02:03:10.199
<v Speaker 2>to shields is A is another way to try to

1861
02:03:10.359 --> 02:03:15.520
<v Speaker 2>suppress or ified interference to audio equipment and sensor connections

1862
02:03:15.560 --> 02:03:19.079
<v Speaker 2>can be limited by using small capacitors one hundred pe

1863
02:03:19.159 --> 02:03:24.600
<v Speaker 2>code of nanofared size across balanced connections mm hmm. Which

1864
02:03:24.640 --> 02:03:27.520
<v Speaker 2>of the following might be used in reducing ARTIF interference

1865
02:03:27.600 --> 02:03:34.600
<v Speaker 2>to audio frequency devices bypassed capacitory? Which of the following

1866
02:03:34.640 --> 02:03:37.199
<v Speaker 2>could be a cause of interference covering a wide range

1867
02:03:37.239 --> 02:03:42.000
<v Speaker 2>of frequencies. Let's see arcing port electrical connection.

1868
02:03:42.560 --> 02:03:44.680
<v Speaker 1>UH see.

1869
02:03:46.319 --> 02:03:48.760
<v Speaker 2>What sound is heard from an audio device experience ARTF

1870
02:03:48.840 --> 02:03:54.279
<v Speaker 2>interference from a single sideband phone transmitter, A steady hum

1871
02:03:55.560 --> 02:04:00.239
<v Speaker 2>transmitters on the air on off, It will be just uh,

1872
02:04:00.520 --> 02:04:04.840
<v Speaker 2>just distorted speech is the big one. What sound is

1873
02:04:04.920 --> 02:04:08.920
<v Speaker 2>heard from an audio device experiencing r F interference from

1874
02:04:08.920 --> 02:04:12.560
<v Speaker 2>the c W uh give some clicking sounds on off?

1875
02:04:12.640 --> 02:04:13.439
<v Speaker 1>Clicking sounds?

1876
02:04:13.520 --> 02:04:18.079
<v Speaker 2>A h was was a possible cause of high voltage

1877
02:04:18.119 --> 02:04:24.000
<v Speaker 2>that produces r F burns. A round wire has high

1878
02:04:24.000 --> 02:04:28.279
<v Speaker 2>impedance on that frequency. What is the possible effect of

1879
02:04:28.319 --> 02:04:34.560
<v Speaker 2>a resonant ground connection yep, The r F usus can

1880
02:04:34.760 --> 02:04:38.479
<v Speaker 2>can can flow on top of on the enclosures of

1881
02:04:38.520 --> 02:04:42.199
<v Speaker 2>the equipment itself. Which of the fine would reduce r

1882
02:04:42.279 --> 02:04:45.399
<v Speaker 2>F interference caused by common mode current on an audio cable?

1883
02:04:46.840 --> 02:04:48.119
<v Speaker 1>Fair right choke on the cable?

1884
02:04:49.039 --> 02:04:54.560
<v Speaker 2>Uh A, How does the how how can the effects

1885
02:04:54.600 --> 02:05:00.520
<v Speaker 2>of brown loops be minimized. UH bond all equipment equipment

1886
02:05:00.600 --> 02:05:01.760
<v Speaker 2>enclosures together.

1887
02:05:03.840 --> 02:05:04.359
<v Speaker 1>Yep D.

1888
02:05:05.560 --> 02:05:07.760
<v Speaker 2>What could be a symptom caused by a ground loop

1889
02:05:07.880 --> 02:05:14.880
<v Speaker 2>in your station's audio connections home on your station and

1890
02:05:15.239 --> 02:05:19.880
<v Speaker 2>receives equipment draws A which technique helps to minimize RF

1891
02:05:19.920 --> 02:05:26.439
<v Speaker 2>hotspots in an amateur station? A binding all equipment together

1892
02:05:26.640 --> 02:05:31.199
<v Speaker 2>ce Why must all metal enclosures of station equipment be grounded?

1893
02:05:32.279 --> 02:05:37.039
<v Speaker 2>Bon fuse sures hazards voltages don't appear on the chassis. D.

1894
02:05:38.039 --> 02:05:42.000
<v Speaker 2>Which of the following direct uh fused power connection would

1895
02:05:42.000 --> 02:05:47.680
<v Speaker 2>be used for one hundred WAT mobile installation the battery

1896
02:05:47.760 --> 02:05:54.119
<v Speaker 2>using heavy gauge wire. It would be a directly to

1897
02:05:54.199 --> 02:05:56.720
<v Speaker 2>the battery with heavy gauge wire if you can. How

1898
02:05:56.760 --> 02:05:59.199
<v Speaker 2>should DC power for one hundred watt HF transceiver or

1899
02:05:59.239 --> 02:06:01.119
<v Speaker 2>not be swashed? Should it not be connected to a

1900
02:06:01.199 --> 02:06:06.319
<v Speaker 2>vehicle's auxiliary power socket? Uh socket may be inadequate for

1901
02:06:06.399 --> 02:06:09.479
<v Speaker 2>the current draw by the transceiver. B Which of the

1902
02:06:09.520 --> 02:06:18.039
<v Speaker 2>fining most most limits in HF mobile installation? UH I

1903
02:06:18.119 --> 02:06:22.039
<v Speaker 2>think efficiency of the electrically short antenna s C. Which

1904
02:06:22.079 --> 02:06:25.119
<v Speaker 2>of the filing may cause receiver receive interference in a

1905
02:06:25.239 --> 02:06:28.720
<v Speaker 2>radio installed in a vehicle, battery charging system, fueled, the

1906
02:06:28.760 --> 02:06:32.920
<v Speaker 2>lever system, controller, the computers, all those things. How does

1907
02:06:32.960 --> 02:06:35.960
<v Speaker 2>a farerite beat or co or core reduce common mode

1908
02:06:36.079 --> 02:06:37.920
<v Speaker 2>r F current on the shield of a collect cable

1909
02:06:38.920 --> 02:06:46.239
<v Speaker 2>uh A, creating an impedance in the current path. Which

1910
02:06:46.399 --> 02:06:51.039
<v Speaker 2>intermodulation products are closest to the original signal frequencies? Uh

1911
02:06:53.399 --> 02:06:58.720
<v Speaker 2>it's the odd order ones to see, Yes, what produces combination?

1912
02:06:58.840 --> 02:07:02.079
<v Speaker 2>What what process can binds two signals in a linear

1913
02:07:02.279 --> 02:07:08.319
<v Speaker 2>circuit or connection to produce unwanted spurious outputs on linear

1914
02:07:08.640 --> 02:07:13.600
<v Speaker 2>So that would be intermodulation. Which of the following is

1915
02:07:13.640 --> 02:07:18.000
<v Speaker 2>an odd order intermodulation product of frequencies F one and

1916
02:07:18.239 --> 02:07:24.439
<v Speaker 2>F two. I think that's going to be odd order intermodulation.

1917
02:07:24.560 --> 02:07:27.159
<v Speaker 2>Would b c F two F one and that minus

1918
02:07:27.279 --> 02:07:30.319
<v Speaker 2>f twoeh two times the fundamental minus F two.

1919
02:07:31.159 --> 02:07:31.920
<v Speaker 1>Gives you that one.

1920
02:07:35.520 --> 02:07:38.600
<v Speaker 2>So there's how you calculate. Man, Remember the intermodulation first

1921
02:07:38.640 --> 02:07:42.159
<v Speaker 2>to mixing products. The auto order modulation refers to harmonics

1922
02:07:42.159 --> 02:07:44.840
<v Speaker 2>as audo order homo extra closesturing to the second harmonic

1923
02:07:44.880 --> 02:07:48.239
<v Speaker 2>of F one the frequency of the second harmonic two

1924
02:07:48.439 --> 02:07:51.319
<v Speaker 2>F That I just answers C that's correct.