Speaker 1: All right, let's continue with our next module. Here.
Speaker 2: We're gonna be talking about reactants, impedance, resonance, and active
Speaker 2: components in this section, So let's talk about reactance. Reactance
Speaker 2: is the resistance to the flow of current caused by
Speaker 2: capacitance or inductance. It's denoted by the letter X, and
Speaker 2: it's measured in homes like resistance capacitive reactants, which is
Speaker 2: the opposite, which is the opposition to AC current flow
Speaker 2: from the store energy in the capacitor is denoted by XC.
Speaker 2: Capacitors behave differently with AC and DC.
Speaker 1: Current with DC.
Speaker 2: When voltage is instantly applied, capacitor looks like a short circuit.
Speaker 2: After charging, it looks like an open circuit. This is
Speaker 2: how it blocks DC signals. However, AC behavior depends upon
Speaker 2: voltage frequency. Here you can see some graft. If you
Speaker 2: have a capacitor, as soon as you apply voltage, it's
Speaker 2: a short circuit and the voltage rises up to the
Speaker 2: applied voltage over a specific set of specific amount of time,
Speaker 2: and when you remove the voltage from the capacitor then
Speaker 2: it slowly decays down to zero volts.
Speaker 1: Again.
Speaker 2: So when a circuit contained a capacitors first, energize, the
Speaker 2: vultage across the capacitor is zero.
Speaker 1: And the current's very large.
Speaker 2: As time passes, the voltage across the capacitor increases and
Speaker 2: the current drops toward towards zero. As a frequency of
Speaker 2: the applied signal increases, the reactive.
Speaker 1: Capacitance decreases, and vice versa.
Speaker 2: What is the reactance of a one nano farreed capacitor
Speaker 2: at two megahertz? Well, first we have to convert megaherts
Speaker 2: the hertz and nanofage to ferreds. Two megaherts is two
Speaker 2: times tens of the six herts. One nano fareed is
Speaker 2: one times ten to the minus nine fair ads, So
Speaker 2: the equation of capacitive reactants is one over two pi
Speaker 2: the frequency times capasit So in this case it's equel
Speaker 2: one over two times three point four times two times
Speaker 2: ten to the six times one times ten to the
Speaker 2: minus nine, which comes out to be seventy nine point
Speaker 2: six ohms. So the capacity of reactants of a one
Speaker 2: nanofarreed capacitor at two megahertz is seventy nine points six omes.
Speaker 2: Inductive reactants is the opposition to ac current flow from
Speaker 2: the stored energy in an inductor and is denoted by XL.
Speaker 2: Behavior with frequency is described as below. XL is equal
Speaker 2: to two pi times the frequency times the inductance in henrys.
Speaker 2: As a frequency F is of the applied signal increases, XL.
Speaker 1: Increases, and vice versa.
Speaker 2: When a circuit containing introductor is first energized, the initial
Speaker 2: current is zero and the full applied voltage appears across
Speaker 2: the inductor. As time passes, the voltage drops down towards
Speaker 2: zero has shown in this figure, and the current increases
Speaker 2: is shown in B. What is the reactance of a
Speaker 2: ten Microhindr inductor at five megahertz? First we convert microhenries
Speaker 2: to Henri's and megahertz to hertz. That way everything has
Speaker 2: the same base units. So five megahurts is five times
Speaker 2: ten to the six hertz. Ten microhendris is one times
Speaker 2: ten to the minus five henris, and from our equation,
Speaker 2: the reactive the inductive reactants is two pi times of
Speaker 2: frequency times l, So in this case it's two times
Speaker 2: three point one four times five times in the six
Speaker 2: times one times ten to the minus five or about
Speaker 2: three hundred and fourteen omes. So the reactance of a
Speaker 2: ten Microhindry inductor at five megahertz is three hundred and
Speaker 2: fourteen homes. Parasitic inductance is unwanted. Parasitic inductance is an
Speaker 2: unwanded characteristic that results from the component's physical construction. The
Speaker 2: coils in a wire wound resistor, for example, create pair
Speaker 2: parasitic in inductance. Wire leads of components at inductance that
Speaker 2: we of parasitic inductance, and in inductors, each pair of
Speaker 2: turns creates parasitic capacitance in series, with the inductance often
Speaker 2: significant enough to disrupt the circuit's operation or affect tuning
Speaker 2: in the radios. Some capacitors made of thin foils.
Speaker 1: Are rolled up.
Speaker 2: The rolled up construction creates parasitic inductance. It's very high
Speaker 2: in electrolytic capacity. This limbits are used to relatively low frequencies.
Speaker 2: Tanelum and ceramic capacitors have little parasitic inductance and can
Speaker 2: be used up to microwave frequencies. What is reactants is
Speaker 2: that the opposition of the flow of direct current caused
Speaker 2: by resistance. Nope, it's the opposition of the flow of
Speaker 2: ultimating current caused by capacitive or inductance.
Speaker 1: What reactance is.
Speaker 2: Which of the following causes opposition to the flow of
Speaker 2: alternating current in an inductor.
Speaker 1: It's going to be reactance.
Speaker 2: Which of the following causes opposition to the flow of
Speaker 2: alternating incurring in a capacitor and its reactance?
Speaker 1: How much?
Speaker 2: How does an A D an AC? How does an
Speaker 2: inductor react to AC As a frequency of the applied
Speaker 2: AC increases, the reactants decreases or does it increase? All right,
Speaker 2: so the frequency increases as the as the applied AC increases,
Speaker 2: which is D as the frequency. As a frequency goes.
Speaker 1: Up, inductance goes up the reactants.
Speaker 2: How does a capacitor react to AC, Well, it's the opposite,
Speaker 2: So as the frequency goes up the reactants and decreases
Speaker 2: in a in a capacitor, So it'd be a what
Speaker 2: unit is used to measure reactants.
Speaker 1: Be the ome?
Speaker 2: What should wire round resistors? Why should wire round resistors
Speaker 2: not be used in RAF circuits? Let's see, Because let's see,
Speaker 2: the resist induction can make circuit performs unpredictables. The terms
Speaker 2: of dis capacitance would two the circuit. So I think
Speaker 2: it's going to be D. Nope, the resistance inductions could
Speaker 2: make the performance unpredictable because there's parasitic because there's parasitic
Speaker 2: reactants in there.
Speaker 1: Okay.
Speaker 2: Impedance is the opposition to current flow in an AC
Speaker 2: circuit caused by resistance, reactants, or any combination of the two.
Speaker 2: It's also impedances is denoted by the letter Z. It's
Speaker 2: measured in ohms. So remember, impedance is the opposition to
Speaker 2: current flow in an AC circuit caused by resistance, reactive,
Speaker 2: or any combination of the two.
Speaker 1: Okay, Like resistance, it's.
Speaker 2: The ratio of voltage to current. It's the inverse of
Speaker 2: impedance is admittance. So resonance indicates a match between the
Speaker 2: frequency at which a circuit or intenda naturally responds to
Speaker 2: the frequency of an applied signal. Resonance occurs when capacitance reactives.
Speaker 2: Reactance is equal to inductive reactants. So when those two
Speaker 2: are equal, then you're gonna have resonance. In a resonance
Speaker 2: series circuit, reactance of L and C cancel, making it
Speaker 2: sh making a short circuit, leaving only the resistance.
Speaker 1: As a circuit's impedance.
Speaker 2: Read Resonance is used in filters and tuned circuits to
Speaker 2: pass or reject specific frequencies, so resonance is a very
Speaker 2: important piece of amateur radio used a lot in our
Speaker 2: RF circuits. In a resonance series circuit, the reactance of
Speaker 2: L and the reactance of C cancel, making this making
Speaker 2: a short circuit. This leaves only the resistance as a
Speaker 2: circuit's impedance. Self resonance resonance can occur when a component's
Speaker 2: expected reactance equals the reactance of its parasitic reactants, called
Speaker 2: self resonance.
Speaker 1: Results.
Speaker 2: Then self resonance results in a component that appears to
Speaker 2: be short or open circuit at the self resonant frequency.
Speaker 2: Above this frequency, the components reactive the reactants switches tight,
Speaker 2: making an inductor capacitive and a capacitor inductive, so that's
Speaker 2: above the self resonance frequency of the device. Impedance transformer
Speaker 2: is a transformer that can change the combination of voltage
Speaker 2: and current while transferring energy. The transformer also changes impedance
Speaker 2: between the primary and the secondary circuits by changing the
Speaker 2: ratio of voltage and current between the primary and secondary circuits.
Speaker 2: The turns ratio controls the transformation in the same ways
Speaker 2: as the ratio of gear teeth and a mechanical transmission.
Speaker 2: So impedance transformers. This is real similar to the volted
Speaker 2: transformer we just saw, except we've got impedance. Now, what
Speaker 2: is the primary impedance of a two hundred ERME load
Speaker 2: is connected to the secondary of a transformer with the
Speaker 2: five to one secondary to primary turns ratio. Well, using
Speaker 2: our equation filling in our numbers, it's two hundred divided
Speaker 2: by one over five, which about eight omes. So if
Speaker 2: I've got a two hundred zero load, if I got
Speaker 2: two hundred oz impedance on one side of a transformer
Speaker 2: and a five to one winding ratio, it will transform
Speaker 2: that impedance to eight to eight excuse me, to eight omes. Okay,
Speaker 2: what's the turns ration? What turns ratio is required to
Speaker 2: change a five hundred, six hundred impedance into a fifty impedance. Well,
Speaker 2: it's going to be the square root of the impedance
Speaker 2: ratio six hundred divided by fifty square root of twelve
Speaker 2: three point four to six. So if I had a
Speaker 2: six hundred oerme impedance on one side of my transformer, I.
Speaker 1: Needed to get to fifty homes.
Speaker 2: I'd have to have a turns ratio of three point
Speaker 2: four to six in my windings.
Speaker 1: Note that the impedance to be changed.
Speaker 2: In this case, six hundred homes can be connected to
Speaker 2: the primary or secondary, but turns ratios are always stated
Speaker 2: with the larger number first three point four six to one,
Speaker 2: not one point three point four to six, because remember
Speaker 2: a transformer, you can hook up both directions, but it's
Speaker 2: always stated with the turns ratio of the primary.
Speaker 1: First and energy sources.
Speaker 2: Ability to deliver power to a load is limited by
Speaker 2: its internal impedance. Amateur transmitting equipment is designed so that
Speaker 2: the internal impedance of its output circuits is fifty homes.
Speaker 2: If the difference between the antenna's system impedance and the
Speaker 2: transmitter output impedance is greater enough, the transmitter may reduce
Speaker 2: output power to avoid damage. So what you need to
Speaker 2: do is put in an impedance matching circuit. This is
Speaker 2: the case where you've got an antenna that's other than
Speaker 2: fifty homes. Most impedance matching circuits are LC circuits and
Speaker 2: duct and capacitors. UH They are called PIE or T
Speaker 2: networks based on how they're configured. On the left is
Speaker 2: the PIE network. You notice it's an inductor with two capacitors,
Speaker 2: and a T network is two capacitors with one inductor.
Speaker 2: Impedis matching can also be performed by special links and
Speaker 2: connections of a transmission line. Okay, what happens when an
Speaker 2: inductive and capacitive reactants are equal in a serious circuit?
Speaker 2: This means emped's are very low pieces equal to the
Speaker 2: I think it's going to be c The resonance causes
Speaker 2: impedans to be very low, so the two cancel each
Speaker 2: other out and you only have the resistance value left
Speaker 2: the real resistance. What is the term of the inverse
Speaker 2: of impedance admittance? What is impedance?
Speaker 1: It's the It's.
Speaker 2: The the ratio voltage to current number similar to equals.
Speaker 1: I are.
Speaker 2: Which of the following devices can we used for impedance
Speaker 2: matching at radio frequencies? A transformer, a pig network, link
Speaker 2: of transmission line, all the choices?
Speaker 1: I think it's all these.
Speaker 2: Remember we talked about a transformer, a pied network, a
Speaker 2: transmission line. All these can be used to transformer match
Speaker 2: What letters used to represent reactants X? What occurs in
Speaker 2: an LC circuit at resonance current voltage or equal?
Speaker 1: Nope? A circuit Nope.
Speaker 2: The inductance, reactants, and capacitance cancel each other. D What
Speaker 2: transformer turns ratio matches and antenna's six hundred one feed
Speaker 2: point to impedance to a fifty zero coaxial cable.
Speaker 1: It's about a three and a half to one a M.
Speaker 2: What happens when an inductor is operated above its self
Speaker 2: resonant frequency? UH, it becomes capacitive. Remember inductor above itself
Speaker 2: resonant inductor becomes capacitive and a capacitor becomes inductive above
Speaker 2: its self resonant frequency. What is one reason to use
Speaker 2: an impedance transformer at a transmitter output?
Speaker 1: Uh?
Speaker 2: Present desired reduced to minimize to present the desired impedance
Speaker 2: with the transformer feed line b.
Speaker 1: KAY.
Speaker 2: Talk about some semiconductor components. The most common active components
Speaker 2: are made of semiconductors. Most are made of silicon or germanium.
Speaker 2: Electrical properties can be controlled by addition of small amounts
Speaker 2: of dopants or impurities such as indium and phosphorus. If
Speaker 2: the impurity creates it an excess of electrons, the result
Speaker 2: is an N type material, and the opposite deficiency of
Speaker 2: electrons is P type So those are the two type
Speaker 2: of semiconductor materials that we commonly use. Where NP type,
Speaker 2: N type and P type are in contact. Where those
Speaker 2: two come together, it's called a P N junction. Okay,
Speaker 2: here's a diode semiconductor junction. That's a diode uses a
Speaker 2: P P type material and an N type P has
Speaker 2: excess electrons, in has deficient electrons. When those two come
Speaker 2: together and a boundary is called the junction. And let's
Speaker 2: see current flows when positive voltage is applied from the
Speaker 2: P type to N type material, that's called Ford bias.
Speaker 2: And if I hope the power up backwards is not
Speaker 2: going to flow, so current flows when positive voltage is
Speaker 2: applied from P.
Speaker 1: To end ford bias.
Speaker 2: Voltage applied in the opposite direction is called reverse bias.
Speaker 2: It pulls electrons away from the junction, so no current
Speaker 2: can flow across the junction. Voltage required to force electrons
Speaker 2: across the through the junction is called forward voltage or
Speaker 2: junction threshold voltage. For silicon diodes, the Ford voltage is
Speaker 2: zero point seven volts. For germanium diodes it's point three volts.
Speaker 2: There's different types of diodes. There's light emitting diodes called
Speaker 2: LED laser diodes, avalanche zine or shot key.
Speaker 1: There's a bunch and they have different they're all diodes.
Speaker 2: They have different applications and different properties and can be
Speaker 2: used for different types of things in your electrical circuit.
Speaker 2: Diodes are rated by their peak inverse voltage. That's the
Speaker 2: maximum voltage they can stand before breaking down Negatively, there's
Speaker 2: specified with their forward voltage how much voltage it takes
Speaker 2: to turn the voltage on to get ford current flow
Speaker 2: exceeding a diodes writing will destroy the diodes internal structure
Speaker 2: junction capacitants when reverse biased layers of the P and
Speaker 2: N type material act like capacitors. The larger the c
Speaker 2: the longer it takes to switch it to conducting forward current.
Speaker 2: So if you want something that switches fast like a
Speaker 2: transmit received dide, or you want something that's got lower
Speaker 2: capacitans in the junction, if we add a third layer
Speaker 2: of semiconductor material, you get a transistor. This is a
Speaker 2: bipolar transistor. You notice you've got two P type materials
Speaker 2: with an end between them. That's called the PNP transistor.
Speaker 2: And if you have N type materials on the end
Speaker 2: with the P type in the middle. It's called it
Speaker 2: N P in transistor. These are the two base six
Speaker 2: types of bipolar transistors. They've got to have power on
Speaker 2: them to function. There's three electrodes. There's the collector, the base,
Speaker 2: and the emitter, and they're controlled by the current flow
Speaker 2: between the It's controlled by the current flow between the
Speaker 2: base and the emitter. Very little base emitter current is
Speaker 2: required for collector emitter current to flow. The control of
Speaker 2: large current by smaller current is called amplification. The ratio
Speaker 2: of collector emitter current to base emitter current is called
Speaker 2: current gain. Current gain for DC signals is abbreviated with beta.
Speaker 1: Current gain for.
Speaker 2: AC signals is HFE. Field effector transistors has three electrodes,
Speaker 2: a diode, a source and a gate. Instead of controlling drain,
Speaker 2: instead of controlling drained source current with gate source current,
Speaker 2: the voltage between gate and the source is used instead
Speaker 2: of current gain, FET has transconductance, which is a ratio
Speaker 2: of source drain current through gate voltage. So bipolar transistor
Speaker 2: uses current to control flow. Field effect transistor used voltage.
Speaker 2: MOSS FETs, which stands for metal oxide semiconductor FETs use
Speaker 2: oxide layer to insulate the gate. So when you look
Speaker 2: at the figure on the right, here here's an inf channel.
Speaker 2: It's got a P material N and a P in
Speaker 2: the middle, and then the opposite is a P channel
Speaker 2: FAT which has an end channel substrate.
Speaker 1: FETs are very sensitive.
Speaker 2: They require only small amounts of voltage to control the
Speaker 2: source drain current. High amplification makes the ideal for use
Speaker 2: of switches both voltage and current. With enough voltage, transistors
Speaker 2: can be driven into saturation, where further increases an input
Speaker 2: results of no change in output. High enough input signals
Speaker 2: can reduce outputs current to to zero.
Speaker 1: Which is called cut off.
Speaker 2: Saturation and cut off conditions are are excellent representations of
Speaker 2: digital on off signals and logical circuits.
Speaker 1: So what is the proximate junction threshold.
Speaker 2: Of a germanium diode and it's about point three volts
Speaker 2: and the forward threshold voltage of a silicon junction diode
Speaker 2: is point seven volts. And what are the operating points
Speaker 2: of a bipolar transistor used as a switch that would
Speaker 2: be saturation and cut off? Which of the following describes
Speaker 2: a mossvat construction. Let's see the gate is rented by
Speaker 2: the gates are separated from the channel by a thin
Speaker 2: insulating layer.
Speaker 1: KAY, tell me about vacuum tubes.
Speaker 2: Vacuum tubes have at least three electrodes called elements.
Speaker 1: The three basic parts are.
Speaker 2: Sm the source of electrons, the electrode to collect the electrons,
Speaker 2: and intervening electrodes that control the flow or the travel
Speaker 2: from source to collector. So you've got a source of
Speaker 2: place to collect them, and something to control them. The
Speaker 2: three parts of a vacuum tube. Compared to transistors, they're
Speaker 2: most like the fet they operate. Tubes operate at high
Speaker 2: hazardous voltage two to three thousand volts, so always exercise
Speaker 2: costume and working around vacuum tubes. A filament or heater
Speaker 2: heats the cathode it's causing it to emit electrons inside
Speaker 2: the tube. The cathode is the source of electrons, and
Speaker 2: the control grid, which is the grid closest to the cathode,
Speaker 2: is used to regulate the electron travel between cathode and plate.
Speaker 2: The screen grid, which is the electrode that reduces grid
Speaker 2: to plate capacitance suppressure grid prevents electrons from traveling from
Speaker 2: plate to control or screen grid, and the plate collects electrons,
Speaker 2: and that's called plate current. Which element of a vacuum
Speaker 2: tube regulates the flow of electrons between cathode and plate.
Speaker 2: That'd be the control grid. What is the primary purpose
Speaker 2: of a screen grid in a vacuum tube to reduce
Speaker 2: grid to plate capacitance. Now we'll talk a little about
Speaker 2: analog ice circuits, and ICE is an electronic circuit formed
Speaker 2: on a small piece of semiconducting material, performing the same
Speaker 2: function as a larger circuit.
Speaker 1: Made from discrete chips.
Speaker 2: Uh ICs can operate over a continuous range of voltages
Speaker 2: and currents. They're used for amplification, filtering, measurement, voltage regulation,
Speaker 2: and power control. Most common analog icees operational amplifier and
Speaker 2: linear voltage regulators op amps are used for DC and
Speaker 2: audio circuits. They're inexpensive source of gain. Linear voltage regulators
Speaker 2: maintain power supply output at constant voltages over a wide
Speaker 2: range of currents. So ICs are used in just about
Speaker 2: everything that we have today. All these modern radios we
Speaker 2: have have lots of chips in them.
Speaker 1: The popular seven symbol.
Speaker 2: Here's what a AMP symbol looks like, shown in a package.
Speaker 2: What's called a dual inline package or a DIP and
Speaker 2: it's got connections one through eight. You can see the
Speaker 2: schematic how it's pinned out, and then there's a two
Speaker 2: twenty package which is real common for a voltage regulator.
Speaker 1: That's what they look like.
Speaker 2: Digital integrated circuits operate with discrete values of voltage and
Speaker 2: current representing the binary numbers between values of zero in
Speaker 2: one that is representing on and off. Digital ICs are
Speaker 2: used for performing computations or controlling functions. The most popular
Speaker 2: logic family is C MOSS, which stands for a complementary
Speaker 2: metal oxide semiconductor technology known for high speed and low
Speaker 2: power consumption. And here's the chart that shows the logic
Speaker 2: family characteristics of the different types of families TTL, SE
Speaker 2: MOSS and SEA MOSS.
Speaker 1: The four thousand.
Speaker 2: Series you can see the operating frequency ranges, power consumption,
Speaker 2: and the supply voltage. The basic building block of digital
Speaker 2: circuits are called gates that perform inversion that is, changing
Speaker 2: one to zero or vice versa in the ore and functions.
Speaker 2: The most common gates in use are the inverter nand
Speaker 2: and nore For more complex functions such as microprocesses and
Speaker 2: signal processors. They're constructed from combinations of these functions. So
Speaker 2: all the inverter nand and nore are the basic building
Speaker 2: blocks for all the big microprocessors that we have. That's
Speaker 2: just a whole bunch of combinations of those gates. Circuits
Speaker 2: that use gates to combine binary inputs to generate a
Speaker 2: binary output or combination of binary outputs are called it's
Speaker 2: called combinational logic. And here's some schematics for some basic
Speaker 2: digital functions with the logical equations and truth tables that
Speaker 2: describe their operations. So if you look a logic symbol
Speaker 2: for a gate A and B and C, so c
Speaker 2: the output if the input, if the inputs are the same,
Speaker 2: if the inputs if any input zero, the output zero.
Speaker 2: If the inputs are there are ones and the output one,
Speaker 2: so they both and they both have to be the.
Speaker 1: Same to have an output of one. An or gate.
Speaker 2: Takes the two inputs and or or it ors them together.
Speaker 2: So if I have a any input has a one
Speaker 2: on it, the output's.
Speaker 1: Going to have a one A two.
Speaker 2: Input and gate. Either A and B are off, the
Speaker 2: gate is off. Both have to be on for the
Speaker 2: gate to be on. For a two input or gate,
Speaker 2: either A or B are on, the gate is on.
Speaker 2: Both have to be off for the gate to be off.
Speaker 2: Can you think of examples where this might be used.
Speaker 2: Maybe a gumball machine you need to insert a coin
Speaker 2: and press a button to dispense. So you've got to
Speaker 2: do this and that then something happens, or an intrusive
Speaker 2: detection the alarm sounds for intrusion, or the front door
Speaker 2: or bedroom window, so either have this window, either this
Speaker 2: alarm or this alarm.
Speaker 1: That's an an or function.
Speaker 2: Schematic symbols for the basic digital functions, with the logic
Speaker 2: equations and truth tables already described in their operations. So
Speaker 2: here's a here's here's an inverter. Whatever the input is,
Speaker 2: it converts it to the opposite, So a zero becomes
Speaker 2: a one, one becomes a zero.
Speaker 1: Uh.
Speaker 2: And the two input nand gate. It's the the two inputs.
Speaker 2: It's it's the invert of the hand gate. So if
Speaker 2: I want the output to be a one of the
Speaker 2: any of the inputs have to be Any of the
Speaker 2: one inputs have to be zero. If I want the
Speaker 2: output to be a zero, both inputs have to be
Speaker 2: a one. So here's a no or gate and against.
Speaker 2: It's the opposite of the or gate. It takes the
Speaker 2: output of the or of the or gate and and
Speaker 2: inverts it. So if I have any input that's a one,
Speaker 2: the outputs a zero. If both inputs are zero, the
Speaker 2: outputs a one, and here's a flip flop. The flip
Speaker 2: flop is used to store.
Speaker 1: The next condition.
Speaker 2: So if I have an input, if my inputs are
Speaker 2: one in one and I get a clock, the outputs
Speaker 2: one in one. If the inputs one in one goes
Speaker 2: to the next state, output is going to be a zero.
Speaker 2: So sequential logic circuits combine binary signals in a way
Speaker 2: that depends on time and on the sequence of inputs
Speaker 2: to the circuits. Basic building blocks for sequential logic is
Speaker 2: the flip flop. It responds to a clock signal that
Speaker 2: causes its output to change based on input.
Speaker 1: The two outputs q and.
Speaker 2: Qbar are always in opposite states, connecting the flip flops
Speaker 2: together to one flip flops output feeds the next one's input,
Speaker 2: which creates a two important circuits called a counter and
Speaker 2: a shift register. In counter logic, the outputs of the
Speaker 2: chain of flip flops make up a binary number of
Speaker 2: or state representing the number of clock signals that have
Speaker 2: been occurred. Each flip flop stores one bit of the
Speaker 2: total count. Highest number of count counter can represent. The
Speaker 2: highest number a counter can represent is two to the end,
Speaker 2: where end is a number of flip flops that make
Speaker 2: up the counter. A three bit counter which has three
Speaker 2: flip flops can count two to the three or eight states.
Speaker 2: A four bit can count sixteen states, a five bit
Speaker 2: thirty two states, et cetera.
Speaker 1: Shift registers.
Speaker 2: If you connect the array of a flip flop slightly differently,
Speaker 2: results in a shift register. Shift register stores a sequence
Speaker 2: of ones and zeros from its input as the flip
Speaker 2: flop outputs. Each clock signal causes the value of the
Speaker 2: shift register's input to pass or shift to the next
Speaker 2: flip flop in the string. Some shift register circuits can
Speaker 2: be configured to shift up and down or forward and backward,
Speaker 2: a simple form of a digital memory r F circuits.
Speaker 2: They're designed to function as either like low level high
Speaker 2: gain amplifiers, mixers, modulators, demodulators, filters.
Speaker 1: They greatly reduce the number.
Speaker 2: Of discrete devices required to build a radio circuit, so
Speaker 2: you can get an RF integrated circuit that has a
Speaker 2: lot of these components already.
Speaker 1: Built into it.
Speaker 2: Monolithic microwave integrated circuits MMC are special types of RFICs
Speaker 2: that work through microwave frequencies and they perform several functions.
Speaker 2: They enable construction of low cost cell phones, GPS receivers,
Speaker 2: and those types of things. So what is meant by
Speaker 2: the term MMIC. It is a monolithic microwave integrated circuit.
Speaker 2: Which of the following is an advantage of C MOSS
Speaker 2: integrated circuits compared to TTL circuits low power consumption. What
Speaker 2: kind of device is an integrated circuit operational amplifier? It's
Speaker 2: an analog device. Which of the following describes the function
Speaker 2: of a two input and gate. Okay, output is high
Speaker 2: only when both inputs are high.
Speaker 1: That would be b.
Speaker 2: How many states does a three bit binary counter have?
Speaker 2: So remember you take.
Speaker 1: Two to the end.
Speaker 2: If it's three, it's two to the end, so that
Speaker 2: would have to be eight.
Speaker 1: What's a shift register.
Speaker 2: Clocked array of circuits that passes that data and steps
Speaker 2: along the array. It's a Okay, microprocessors and microcontroller I
Speaker 2: see that are capable of performing millions of computing instructions
Speaker 2: per second. That's what a microprocessor is programs must be
Speaker 2: stored in memory devices so the microprocessor can read the instructions.
Speaker 2: There's volatile memory, which loses the memory when the power
Speaker 2: is removed. There's non volatile memory, which stores the data permanently.
Speaker 1: Even with the out power.
Speaker 2: And there's random access memory, which can be read and
Speaker 2: right from or written to. Then there's read only memory,
Speaker 2: which stores data permanently cannot be changed. Data interfaces. Microprocessors
Speaker 2: communicate through data interfaces. There's two types, serial and parallel interfaces.
Speaker 2: Serial transfers one bit at a time in each each direction.
Speaker 2: Parallel transforms multiple bits in each for each operation. One
Speaker 2: byte is typically eight bits and one bit.
Speaker 1: There you go.
Speaker 2: Amateur equipment uses two types of devices to present information visually,
Speaker 2: indicators to prevent to present information visually, either indicators or displays.
Speaker 2: Indicators present on off information, usually by the presence of
Speaker 2: the absence of light or color. Common indicators include incandescent
Speaker 2: light bulbs and light emitting diodes. For indicators displays, they
Speaker 2: present textra graphics, information, and visual film. LEDs have large
Speaker 2: and largely replaced incandescent light bulbs and amateur equipment. They
Speaker 2: last longer, can be turned on off more quickly and
Speaker 2: use less power and generate less heat. They're also available
Speaker 2: in many colors, and they're made from special types of
Speaker 2: semiconnecting material that light that emit light when the p
Speaker 2: in junction is forward bias, so LED, like the term says,
Speaker 2: is a diode. Liquid crystal display, probably the most common
Speaker 2: type of display, is created by sandwiching liquid crystal between
Speaker 2: between glass panels. A pattern of electrodes is printed in
Speaker 2: a thin film on the front panel, with a single
Speaker 2: electrode covering the rear panel. Boltage is applied to the
Speaker 2: front panel, causing the crystal to twist and a configuration
Speaker 2: that blocks light. LCDs require ambient or backlighting the light
Speaker 2: source behind the crystal layer since layer crystal layer. Since
Speaker 2: the crystal layer does not regenerate light on its own.
Speaker 2: Compared to LCDs, LEDs have higher contrasts where there is
Speaker 2: a high ambient light on a sunny day. How's an
Speaker 2: LED bias when emitting light? It's forward biased. We're gonna
Speaker 2: be talking about practical circuits, basic test equipment, all right, Yeah,
Speaker 2: amateur radio electronic equipment requires DC power, so a power
Speaker 2: supply is required to turn to make it run from
Speaker 2: household AC power. Most amateur radio equipment uses DC power
Speaker 2: thirteen point eight volts, which is chosen to be compatible
Speaker 2: with vehicle power systems. Power supplies have three basic parts,
Speaker 2: the input transformer, erectifire and filter regular output circuit. There's
Speaker 2: two types of rectifier circuits here. A halfway rectifier converts
Speaker 2: only one half of the input waveform. This creates a
Speaker 2: series of pulses of current and the load of the
Speaker 2: same frequency as the input voltage. A full wave rectifier
Speaker 2: converts the entire input wave from.
Speaker 1: Three hundred and sixty degrees.
Speaker 2: This is this is really two half wave rectifiers operating
Speaker 2: alt on the ultimate half cycles. It requires that the
Speaker 2: transform to the center tap to provide a pattern a
Speaker 2: return path for current following the load. So if you
Speaker 2: take a look at the picture here on the right,
Speaker 2: so halfway rectifier, the output of a halfway so you
Speaker 2: got AC coming in and the dialde blocks half of
Speaker 2: the negative cycles, so you get an output that looks
Speaker 2: like this. On a full wave rectifire, you block half
Speaker 2: of it come in one direction and half it go
Speaker 2: in the other direction, and so you get you get
Speaker 2: all you get all the you get the negative sineway
Speaker 2: shows up on the top. It conducts in the opposite direction.
Speaker 2: I get three piece through three voltages here versus six
Speaker 2: on on this end, so I'll have less ripple. The
Speaker 2: advantage of a full wave rectifiers that the output is
Speaker 2: produced during the entire three sixty degrees of the wave cycle.
Speaker 2: It's more efficient. The output from full wave rectifiers in
Speaker 2: a series of pulses that twice the frequency of the
Speaker 2: input voltage. So if my input is so my input
Speaker 2: voltage at sixty hertz, full wave rectifier is going to
Speaker 2: have one hundred and twenty hertz frequency range. Here's a
Speaker 2: full wave rectifier. You can see this circuit adds two
Speaker 2: more to adds to two more dials for total of four,
Speaker 2: but eliminates the need for the center tap winding. Another
Speaker 2: type of full wave rectifier. This circuit adds two diodes
Speaker 2: total of four, but eliminates the need for center tap winding.
Speaker 2: Rectifier output pulses.
Speaker 1: Are used well.
Speaker 2: These full wave rectifiers are used in power supply filter circuits.
Speaker 2: Rectify our output pulses of DC current don't provide a
Speaker 2: stable voltage for direct use by electronics. The variation in
Speaker 2: output vultures is called ripple pulses must be smooth out
Speaker 2: by a filter network, which consists of capacitors or capacitors
Speaker 2: and inductors. The most common way to reduce ripple is
Speaker 2: a filter capacitor or capacitor input filter. Older high voltage
Speaker 2: circuits may use what's called choke conductors, so power supply
Speaker 2: safety fuses is the primary. Fuses in the primary are
Speaker 2: used to protect against short circuits or excessive current loads.
Speaker 2: Bleeder resistors discharge stored energy when the supply is turned off.
Speaker 2: So when you turn off a power supplies, sometimes you
Speaker 2: have like a light one you can see the light
Speaker 2: stay on and it finally goes off. That's the bleeder
Speaker 2: resistor in there feeding off the voltage. Because a lot
Speaker 2: of these power supplies have a large capacitor on them
Speaker 2: to get rid of that ripple, and if you don't
Speaker 2: bleed off that charge, it will stay there for a while.
Speaker 2: So that's called a bleeder resistor does that. Working on
Speaker 2: power supplies, you need to wait for the bleeder resistor
Speaker 2: to discharge or eat the energy, even if it's unplugged.
Speaker 1: Okay.
Speaker 2: Switch mode power supplies, the AC input is first rectified
Speaker 2: and filtered a transistor switched a transistor. Switched pulses at
Speaker 2: high frequency usually twenty kill hers in that range or more,
Speaker 2: transfer energy to the filter capacitor, which smoothes out the ripple.
Speaker 2: High frequency enables power supply to quickly change to current
Speaker 2: demands and means that small lightweight inductor to capacitors can
Speaker 2: be used to filter the output. Here's a block diagram
Speaker 2: of a switching power supply AC's first input to the rectify.
Speaker 2: Its first ac input is first rectified and filtered transistor.
Speaker 2: Switch then supplies current pulses to a small doctor or transformer,
Speaker 2: which transfers the energy into another filter capacitor that smooths
Speaker 2: the pulses for a steady output voltage. The high frequency
Speaker 2: of the pulses means that the supply can react quickly
Speaker 2: to changing current demands. The high frequency also means that
Speaker 2: small lightweight inductors and capassitors can be used to smooth
Speaker 2: out the pulses and the filter and filter the output.
Speaker 2: So what is the function of a power supply bleader resistor? Well,
Speaker 2: you remember it's it's there to remove the To remove
Speaker 2: the voltage, it discharges the capacitor the filter capacitors when
Speaker 2: the power is removed, which of the following components are
Speaker 2: used in power supply filter network diodes, transformers and transducers,
Speaker 2: capassitors and inductors.
Speaker 1: It have to be c.
Speaker 2: Which type of rectifier circuit uses two diodes and a
Speaker 2: center tap transformer via the full wave rectifier? What is
Speaker 2: characteristic of a half wave rectifier and a power supply
Speaker 2: only when doubt is required that recal frequency is twice
Speaker 2: out of the current can be drawn A only has
Speaker 2: one diete half wave rectifier. What portion of the AC
Speaker 2: signal is converted to DC by a half wave rectifier
Speaker 2: one hundred and eighty degrees? What portion of AC cycle
Speaker 2: is converted to d C by a full wave rectifier
Speaker 2: three hundred and sixty degrees. It's doing the full wave.
Speaker 2: What is the output waveform of an unfiltered full wave
Speaker 2: rectifier connected to a resistive load series of DC pulses
Speaker 2: at twice the frequency of the AC output When you
Speaker 2: re memory of the full wave rectifier, You've got both
Speaker 2: the high end the lows, so it's twice the frequency
Speaker 2: coming out. Which of the following is characteristic of a
Speaker 2: switch mode power supply as compared to a linear power supply.
Speaker 2: High I put that the viewers circuits. High frequency. It's
Speaker 2: going to be higher frequency operation, the use of smaller components. Okay,
Speaker 2: now we're going to talk about batteries and chargers. There's
Speaker 2: two types of batteries, primary and secondary. Primary usually disposable,
Speaker 2: discarded after discharging. Battery chemistry is usually carbon link, alkaline
Speaker 2: or silver nickel. Referably to secondary batteries for emergency operation.
Speaker 2: Because AC power may not be available for charging the secondary,
Speaker 2: they can be recharged reused many times. Battery chemistries include nickel, cadmium, nickel,
Speaker 2: metal hydride, litimion, lead acid. Here's a charge that shows
Speaker 2: some of the different battery types and their power ratings.
Speaker 2: Just some interesting information about them. Hey, storage batteries. You know,
Speaker 2: Larger secondary batteries use for emergency or portable power to
Speaker 2: replace power supplies operating from AC power. Usually the battery
Speaker 2: chemistry of these is lead acid or liquid electrolyte gel electrolyte.
Speaker 2: They're rated of twelve volte batteries, but are actually thirteen
Speaker 2: point eight bolts. Lead acid batteries can produce useful power
Speaker 2: down to about ten point five bolts. Discharging below minimum
Speaker 2: voltage will reduce the battery life limiting amount of current
Speaker 2: drawing keeps the battery cool and extends its life, so
Speaker 2: you know be conscious of that. Some battery types nickel
Speaker 2: cadm nickel cadmiums are designed to have low internal resistance
Speaker 2: to supply high discharge currents. So based on your application
Speaker 2: of your battery, you may be a certain type of
Speaker 2: battery that's for the to be right for your application.
Speaker 2: Batteries slowly lose charge when they're not in use. That's
Speaker 2: called self discharge. You can be minimized by keeping the
Speaker 2: battery cool and dry, but avoid freezing. Expanding water can
Speaker 2: crack the case or damaging electrodes. Some alternate power sources
Speaker 2: a solar power photo voltaic conversion of sunlight to electricity.
Speaker 2: Solar panels are cells are actually a special type of
Speaker 2: diode silicon p injunctions. When solar cells, photons are absorbed
Speaker 2: by electrons, giving them enough energy to travel across the
Speaker 2: p in junction and create DC current flow. The ford
Speaker 2: voltage created about half of a volt is called the
Speaker 2: open circuit voltage. When solar power systems require substantial energy storage.
Speaker 2: When connecting is so solar panel to a lithium ion
Speaker 2: phosphate battery use a charge controller to avoid overcharging the battery.
Speaker 2: You want to make sure you use the proper the
Speaker 2: proper the proper controllers. You need something between your solar
Speaker 2: panel and your batteries as a solar panel charger. Solar
Speaker 2: connections are made through a series connected diode to prevent
Speaker 2: damage from discharging back through the panel during periods of
Speaker 2: low illumination produce voltage. Solar panels and solar cells are
Speaker 2: made of silicon pian junctions are exposed to sunlight and
Speaker 2: a range in a series parallel configuration. In the configuration
Speaker 2: in what configuration are the individual cells and a solar
Speaker 2: panel connected together. They're connected in a series parallel combination.
Speaker 2: What is the approximate open circuit voltage from a fully
Speaker 2: illuminated silicon photovotaic sell It's zero point five volts. Why
Speaker 2: should a series diode be connected between a solar panel
Speaker 2: and a storage panel that is being charged by the
Speaker 2: panel to prevent discharge of the battery through the panel
Speaker 2: during times of low or no illumination. What precaution should
Speaker 2: be taken when connecting a solar panel to a lithium
Speaker 2: iron phosphate battery. A solar panel must have a charge controller. Again,
Speaker 2: You've got to have something in between your solar panel
Speaker 2: and your battery. What is the minimum allowable discharge voltage
Speaker 2: for maximum life of a standard TWEBAL lead acid battery,
Speaker 2: and that's ten point five volts? Do you get below
Speaker 2: ten point five volts your batteries? I can produce any
Speaker 2: more power on a lead acid What is advantage of
Speaker 2: batteries with low internal resistance that have a higher discharge current.
Speaker 2: That's the main thing. Let's talk about connectors. There's some
Speaker 2: connection technology. Pins are contacts that extend out of the
Speaker 2: connector body, male sockets or hollow recess contacts. We call
Speaker 2: those the female. Keyed connectors specially shaped bodies or inserts
Speaker 2: to prevent damage from connecting m in correctly. So usually
Speaker 2: connectors are keyed so you can't you know, so they
Speaker 2: can't physically connect them wrong. Plugs are connectors installed on
Speaker 2: the ends of cables. Jacks or receptacles are connectors installed
Speaker 2: on equipment. Adapters make connections between two different types of connectors.
Speaker 2: Styles and splitters divide signals between two connectors. There's a
Speaker 2: picture of some common connectors used in amateur radio. On
Speaker 2: the power connector side, mulex connectors, the Anderson power pole
Speaker 2: that antijacks, binding posts, terminal scripts, you can terminals that
Speaker 2: are crimped to the ends of wires. There's all kinds
Speaker 2: of different types of tempt UH wire terminals that that
Speaker 2: that that that can be used and powerpole connectors have
Speaker 2: become the standard used by areas. Anderson connectors are sexless.
Speaker 2: By standardizing on a single UH style, equipment can be
Speaker 2: easily shared and replaced. And we do use that in
Speaker 2: all of our area stuff here, all my stuff that
Speaker 2: I use in my home shack is all converted over
Speaker 2: to the Anderson powerpool type. Makes a lot easier to
Speaker 2: connect everything together. UH. Note that these are crimp terminals,
Speaker 2: so you need special crimping tools to attach the wires
Speaker 2: to the lugs. Avoid using fliers. Use the right tools
Speaker 2: for the job. That's pretty important. So audio connections, they
Speaker 2: come in quarter inch and eight inch are the most popular,
Speaker 2: and they have a contact at the end of the
Speaker 2: plug which is called the tip, and the connect there
Speaker 2: at the base is called the sleeve. UH. The third
Speaker 2: contact and some of them is in the middle and
Speaker 2: it's called the ring. Bunnyl plug jack's also called r
Speaker 2: c as are used for audio, video and lower level
Speaker 2: r F signals and control signals. Use the lot for
Speaker 2: between your amplifier for your push to talk lines. Here's
Speaker 2: here's some pictures of some RF connectors. These are a
Speaker 2: lot of these are coaxial type connectors. Each type is
Speaker 2: especially especially made to carry r F signals and preserve
Speaker 2: the shielding of the coax Cable adapters are available, you know,
Speaker 2: to connect one style to another. These are the most
Speaker 2: common ones. For US, we use the h U h F,
Speaker 2: the p L two fifty nine and SO two thirty nine.
Speaker 2: The N types B n c's. Those two are probably
Speaker 2: the most common. Radio signals require special connectors to be used.
Speaker 2: Are frequencies. Connectors may have about the same impedance as
Speaker 2: the feed line, or some of the signal will be
Speaker 2: reflected by the connector. Most common connector is the UHF family.
Speaker 2: UHF here does not mean ultra high frequency. UHF connectors
Speaker 2: are typically used up to one hundred and fifty megaherts
Speaker 2: and can handle legal transmit power at HF. UHF connector
Speaker 2: drawbacks do have lack of weather proofing, inconsistent performance above
Speaker 2: one hundred and fifty megahertz, limited power handling, type in
Speaker 2: series our connectors address some of those drawbacks. They can
Speaker 2: be used up to ten gigahertz. BNC connectors are used
Speaker 2: for low power common in handhelds, for and for antennas
Speaker 2: upper limit for low SWR operations for gigahertz. SMA connectors
Speaker 2: are small threaded connector designed for miniature coacts related to
Speaker 2: eighteen gigahertz, also used for hand for handhelds. Those are
Speaker 2: the those are the most common ones that you see.
Speaker 2: A lot of your hpees have SMAs and uh Some
Speaker 2: are male, some are females. Some are reverse mail to.
Speaker 2: When you're buying antennas and connectors that that mate that
Speaker 2: mate with them, you need to double check what you've
Speaker 2: got on data connector. Digital data's exchanged between radios and
Speaker 2: computer equipment UH now more than it used to in
Speaker 2: amateur radio. We have a lot more data connections on
Speaker 2: our radios. Uh D type connectors are used for R
Speaker 2: S two thirty two or comport interfaces. The model number
Speaker 2: of a D type connector specifiers for a number of
Speaker 2: circuits and a P or s depending on pins or sockets.
Speaker 2: U dB nine connector has nine pins and those are
Speaker 2: typical use for the comports on PC's not as much
Speaker 2: so anymore. Okay, what's a typical upper frequency uh for
Speaker 2: lowest of your operation on a fifty OME B and
Speaker 2: C connector?
Speaker 1: You remember where it was?
Speaker 2: I think it was four gigaherts?
Speaker 1: See yep.
Speaker 2: Which of the following describes a type end connector moisture
Speaker 2: resistance up to ten gigaherts? I think that's right. The
Speaker 2: end connector has got some environmental features that makes it
Speaker 2: good for outside use. What's an SMA connector? I know
Speaker 2: it's a small threaded connector or suitable for signals up
Speaker 2: to several gigaherts. And those are real comment like I said,
Speaker 2: on hds, because they're small.
Speaker 1: More than anything.
Speaker 2: Which of these types connectors is commonly used for low
Speaker 2: frequency or DC signal connections to a transceiver. That would
Speaker 2: be the RCA phono type. All right, we're going to
Speaker 2: talk about some basic test equipment now. Analog and digital
Speaker 2: meters a volt oh meter, VOM or a multimeter is
Speaker 2: the simplest and very versatile piece of test equipment. There's
Speaker 2: two types. Analog and digital. Volt meter can measure voltage,
Speaker 2: current resistance, can check continuity, check diodes, test transistors Some
Speaker 2: of them have frequency counters on them, some measure capacitance inductance,
Speaker 2: and a lot of them have an interface to a
Speaker 2: PC to record the readings. Digital multimeters offer great precision,
Speaker 2: greater precision than analog meters to find a heat or
Speaker 2: a minimum value, for example, when they're just in a
Speaker 2: tune in a circuit. Experienced hands often prefer analog meters
Speaker 2: easier to just watch the analog meter move in a
Speaker 2: display than on a digital meter. You can watch the
Speaker 2: needle find its thaying. On an analog meter, it's thinking
Speaker 2: and settling down. It just depends on what you're trying
Speaker 2: to measure.
Speaker 1: Meters.
Speaker 2: Meters should affect the circuit being measured in the smallest
Speaker 2: degree possible. With measuring voltage, meters should have a high
Speaker 2: input impedance so that it places the minimum load on
Speaker 2: the circuit we're going to talk about. The next is
Speaker 2: the assilloscope. Sill scope provides a visual display of voltage
Speaker 2: versus against time. The display is updated thousands or million
Speaker 2: times per second to give a real time view. The
Speaker 2: signal's characteristics allows for the measurement of fast changing wave
Speaker 2: forms that can't be measured by other meters. Signals are
Speaker 2: connected to the scope through horizontal and vertical channel amplifiers.
Speaker 2: Amplifier gain is variable to adjust vertical sensitivity of the
Speaker 2: scopes display.
Speaker 1: Monitoring.
Speaker 2: The silloscopes are sometimes used to monitor the transmitted signals
Speaker 2: by connecting the attenuated RF output of the transmitter to
Speaker 2: the vertical channel of the scope. This assists in adjusting keywaveforms,
Speaker 2: microphone gain, and speech processing. When adjusting keying waveforms such
Speaker 2: as a CW transmitter, the operator can see on the
Speaker 2: scope display the effects of the any adjustments or conditions
Speaker 2: that might cause distortion or key clicks of the transit
Speaker 2: of the retransmitted signal.
Speaker 1: One thing about.
Speaker 2: Scopes, Some of these new radios have an audioscope on
Speaker 2: them and you can actually see your wave form of
Speaker 2: your voice and those kinds of things. Those are kind
Speaker 2: of deep, okay. Impedance and resonant measurements. An intented analyzer
Speaker 2: contains a CW signal generator, frequency counter, SWR bridge, and
Speaker 2: an impedance meter all in one package. They connect to
Speaker 2: the antenna feed line to measure standing wave ratio without
Speaker 2: having to transmit a signal at high power. They measure
Speaker 2: feed line velocity factor electrical length, characteristic impediance, and other parameters.
Speaker 2: They're very handy item they have around the shack. Because
Speaker 2: they use small signals. Accuracy can be affected by strong
Speaker 2: signals from nearby transmitters, so you have to be careful.
Speaker 2: So somebody's transmitting near by, they can maybe affect your reading,
Speaker 2: but it doesn't happen much. But an antenna analyz there's
Speaker 2: a nice piece of equipment to have around the shack.
Speaker 2: Field strength and r F power meters UH, they're useful. UH.
Speaker 2: Other useful tests that include antenna efficiency and radiation pattern UH.
Speaker 2: Those can be measured with the field strength meter. Field
Speaker 2: strength meters are often used for comparing relative levels of
Speaker 2: r F output during antenna and transmitter adjustments. Radiation pattern
Speaker 2: is measured by placing field strength meter in one location
Speaker 2: in rotating the antenna, or the meter can be carried
Speaker 2: at different locations that determine the radiation pattern of a
Speaker 2: fixed antenna. They're useful that there would be a very
Speaker 2: useful piece of equipment. I have had one. I've done
Speaker 2: some antenna measurements. Antenna measurements are very difficult to do though,
Speaker 2: so directional watt meters U can be used to measure
Speaker 2: both forward and reflected power. Standing wave ratio can be
Speaker 2: calculated from forward and reflected power measurements. The SWR formulas
Speaker 2: right down there. It's the ratio of the power reflected
Speaker 2: versus powered forward And what type of test equipment contains
Speaker 2: horgonal and vertical channel amplifiers. That would be the silloscope.
Speaker 2: Which of the following is an advantage of the sell
Speaker 2: scope versus a digital volte meter? You can see complex
Speaker 2: waveforms on a scope. Which of the following is the
Speaker 2: best instrument to use when checking the key ray form
Speaker 2: of a CW transmitter?
Speaker 1: That would be a.
Speaker 2: Silloscope. What signal source is connected to the vertical input
Speaker 2: of a asilloscope when checking the RF envelope pattern of
Speaker 2: a transmitted signal? That would be the attenuating r F
Speaker 2: output of the transmitter. Right, So you attenuated mean you
Speaker 2: can't hook your hundred watt radio into your scope? You
Speaker 2: want to attenuate it, take a portion of it to
Speaker 2: look at. Okay, So that's what they're talking about there.
Speaker 2: Why do volt meters have high input impedians You don't
Speaker 2: want to load the circuits you're being measureds So what
Speaker 2: would be d decreases the loading on circuits being measured.
Speaker 2: What is an advantage of a digital volt meter as
Speaker 2: compared to an analog meter. I think it has higher precision. Yep,
Speaker 2: let's see what when is an analog meter preferred to
Speaker 2: a digital meter. So, I think that's when you're adjusting
Speaker 2: circuits for minimum or maximum value. If I'm tuning something,
Speaker 2: an SWR mater with an analog meter is really nice
Speaker 2: to tune. It's you just call them dip meters.
Speaker 1: You can.
Speaker 2: It's easy with an analog meter to find that that
Speaker 2: dip is as opposed to waiting for the digital meter
Speaker 2: to settle down, so.
Speaker 1: It would be d.
Speaker 2: Which of the following can be determined with the directional
Speaker 2: watt meter. Let's see antenna front to back ratio. That's
Speaker 2: what it sounds like. A directional lot meter. Oh standing,
Speaker 2: I'm sorry, I'm thinking the field streak meter. Directional lot
Speaker 2: meter you would use to measure forward and reflective power
Speaker 2: standing wave ratio, which on the phone must be connected
Speaker 2: to an antenna analyzer when it is being measured. For
Speaker 2: sw r U, the receiver transmitter antennae feed line thinks
Speaker 2: c Yep, you don't need your transmitter connected when you're
Speaker 2: checking the antenna and feed line. What effect can strong
Speaker 2: signals from nearby transmitters have on an antenna analyzer. They
Speaker 2: can desensitize it, receive power. Let's see, since I can
Speaker 2: also cause you minds nope, receive power. The interfaces interferes
Speaker 2: with the r SWR being. If I'm trying to measure
Speaker 2: something locally and Jason's living next door to me and
Speaker 2: he powers up his kill A, whatte amplifier he can
Speaker 2: affect my my little SWR meter? Which of the phone
Speaker 2: can be measured with an intenna analyzer? H power pedants
Speaker 2: impedance of the coacs C. All right, Our next section
Speaker 2: we're going to talk about is some of the basic
Speaker 2: modes in bandwidth, some radio building blocks and transmitters. Okay,
Speaker 2: Varying the power or amplitude of a signal to ad
Speaker 2: speech or data is called amplitude modulation or am.
Speaker 1: Uh.
Speaker 2: The information is contained in the signal's envelope the max
Speaker 2: values of the instantaneous power for each cycle.
Speaker 1: The process of recovering.
Speaker 2: Speech or music from an A and envelope is called detection.
Speaker 2: So we've got amplitude modulation and then to generate in
Speaker 2: detection to decode. AM signals are composed of a carrier
Speaker 2: and two sidebands.
Speaker 1: It's called upper and lower sideband.
Speaker 2: When an AM signal is modulated by a tone, the
Speaker 2: two side bands are steady and unchanging. Upper sideband is
Speaker 2: higher in frequency than the carrier. Lower sideband is lower frequency.
Speaker 1: Than the carrier.
Speaker 2: An AM signal with the carrier and one side band
Speaker 2: removed is called single sideband. Single sideband transmissions have more
Speaker 2: range than AM signals because all the single sideband's power
Speaker 2: is contained in a single sideband. The single sideband smaller
Speaker 2: bandwidth makes it possible to fit more signals into a
Speaker 2: fixed frequency range. Modes that vary the frequency of a
Speaker 2: signal to add speech or data in information are called
Speaker 2: frequency modulation. Frequency is the frequency is varied is in
Speaker 2: proportion to the instantaneous amplitude of the modulated signal. Phase
Speaker 2: modulation is created by varying the signal's phase angle.
Speaker 1: These signals have a constant.
Speaker 2: Power, whether module or not, so AM and PM signals
Speaker 2: again if constant power, whether the modulator or not. The
Speaker 2: FCC divines bandwidth as the width of a frequency band,
Speaker 2: outside of which the mean average power of the transmitted
Speaker 2: signal is at least twenty six dB below the mean power.
Speaker 2: So what does that mean? So if I'm talking, this
Speaker 2: is my voice range. Here somewhere down here is my
Speaker 2: noise floor. There is where my noise floors starts. So
Speaker 2: when this gets between twenty six dB down from here,
Speaker 2: that's where they say, that's your bandwidth from your peak
Speaker 2: down to twenty six dB on each side that ratio,
Speaker 2: there is your bandwidth.
Speaker 1: Okay.
Speaker 2: The difference in frequency between the lowest and highest component
Speaker 2: of a composite signal is a signals bandwidth. The FCC
Speaker 2: limits signal bandwidth so that many stations and types of
Speaker 2: signals can share the limited amount of spectrum space. So
Speaker 2: we're limited to about three killer hurts on the single
Speaker 2: side band. That's why I show, okay, amateur signals. So
Speaker 2: here's are different types of signal types their typical bandwidth
Speaker 2: AM to six kill hurts, amateur TV six megahurts.
Speaker 1: I remember amateur TVs could be up higher.
Speaker 2: U single side band voice two to three killer hurts
Speaker 2: is typical bandwidth. Digital single side band three killer hurts,
Speaker 2: c W one hundred to three hundred hertz, and FM
Speaker 2: voice five to sixteen killer hurts, okay.
Speaker 1: So what's a link budget when.
Speaker 2: You when you add up all the power gain and
Speaker 2: losses in a signal transmission from source to receiver.
Speaker 1: UH, that's called the link budget.
Speaker 2: And amateur radio, this is generally the transmitted power and
Speaker 2: antenna gains from the sending station minus the any system
Speaker 2: losses the receiving station experiences. Losses result from iyesper refraction, attenuation,
Speaker 2: or variety of other causes. Link margin is a difference
Speaker 2: between the minimum power that's level needed to receive a
Speaker 2: signal and the actual power of the level received signal,
Speaker 2: and it's usually measured in d n dB. So if
Speaker 2: I'm trying to talk to Jason in Texas from Huntsville
Speaker 2: and I'm running thirty watts and he can just barely
Speaker 2: hear me, we'll say we've got a link margin of
Speaker 2: about zero.
Speaker 1: That's perfect.
Speaker 2: I crank up my amplifier to one hundred dbt He goes, wow,
Speaker 2: I can hear you this much better, ten dB better
Speaker 2: than I got a link margin of ten of ten
Speaker 2: of ten dB. So's it's how much margin do I
Speaker 2: have before he can't hear me anymore?
Speaker 1: Right? How much power up?
Speaker 2: So that that's your link margin, and my link budget
Speaker 2: was my amplifier is this much? My hand in the
Speaker 2: gain is this, I lose this much through the atmosphere.
Speaker 2: And then on Jason's side, his antenna has this much
Speaker 2: as amplifiers this and he can receive it. So it's
Speaker 2: that whole link budget, and then the link margin is
Speaker 2: how much extra I have to make that communication happen. Okay, So,
Speaker 2: what's the name of the process that changes the phase
Speaker 2: angle of an RF signal to convey information? Well, that's
Speaker 2: phase modulation. B what's the name of the process that
Speaker 2: changes the instantaneous frequency of an RF wave to convey information?
Speaker 2: All right, instantaneous, I'd be frequency modulation. Okay, what type
Speaker 2: of modulation varies the instantaneous power of the RF signal?
Speaker 1: That would be amplitude modulation.
Speaker 2: Which of the following phone emissions uses the narrowest single
Speaker 2: the narrowest band bandwidth single sidebands is the smallest here? Okay?
Speaker 2: What is a link budget? Some of transmit power and
Speaker 2: gains system laws seen by others.
Speaker 1: It's gonna be c.
Speaker 2: It's some of the transmit power intended gains minus the
Speaker 2: system losses as seen at the receiver.
Speaker 1: What's link margin.
Speaker 2: That'd be the difference between received power level and minimum required.
Speaker 1: Signal level at the input of the receiver.
Speaker 2: Nearly all radios are made up of a few fundamental
Speaker 2: types of circuits. There's a variety of ways circuits are built,
Speaker 2: but basic functions are the same. Radio circuits that perform
Speaker 2: signal generation. Processing functions can also be performed on a
Speaker 2: digital data by software. In a radio that uses digital
Speaker 2: signal processing referred to as a software defined radio.
Speaker 1: Filters are used to attenuate.
Speaker 2: Or reduce in strength or past signals. A lot of
Speaker 2: the modern HF transceivers you buy will have attenuators, filters,
Speaker 2: a lot of cool things circuits in them to help
Speaker 2: you improve your received performance. Filters are classified by their
Speaker 2: response how they act to signals. Range of the signals
Speaker 2: the range of signals that are passed by filters called
Speaker 2: the pass band. The range of signals attenuated by the filter,
Speaker 2: it's called the stop band, also known as rejection. Generic
Speaker 2: filter response curves here are shown. If you look at
Speaker 2: the first example on the left, this is a low
Speaker 2: pass filter. It passes all this these frequencies and then
Speaker 2: attenuates frequencies above. This is passing a low frequency it's
Speaker 2: a low pass filter. Here's a high pass filter. It
Speaker 2: attenuates the lower frequencies than it passes the higher frequency,
Speaker 2: so that's a low pass high pass filter. The cutoff
Speaker 2: frequency is the frequency which the output signal power.
Speaker 1: Is reduced to half.
Speaker 2: So if you remember from our earlier charts, three dB
Speaker 2: down from whatever this level is year wherever three dB is,
Speaker 2: that's called the stop band or the cutoff, the beginning
Speaker 2: of the stop band the cutoff, So it's above a
Speaker 2: low frequenty a low pass filters cut off frequency. The
Speaker 2: tenuation generally increases with frequency, so the tenuation increases, which
Speaker 2: means it gets it rejects the frequencies there. So uh,
Speaker 2: the cutoff is the three d B point of the
Speaker 2: norminal pass band. There's a band pass filter where you,
Speaker 2: you know, attenuate a certain frequencies below a certain amount,
Speaker 2: and you attenuate above a certain amount, and what's in
Speaker 2: the middle is what the band that's passed, called the
Speaker 2: pass band.
Speaker 1: Also a thing called a.
Speaker 2: Notch where you can have a you can have a
Speaker 2: filter come in and pass everything except a frequency you're
Speaker 2: you know, a little band that you're interested in, and
Speaker 2: that's a notch filter.
Speaker 1: Okay, that's the bandwidth of that.
Speaker 2: Let's see, low pass filters passes all frequencies below the
Speaker 2: cutoff of little or no attenuation. UH.
Speaker 1: It is reduced by half. Talk about high pass filters.
Speaker 2: Opposite, it passes things above a certain cutoff frequency. Band
Speaker 2: pass filters have upper and lower cutoff frequencies and pass
Speaker 2: the signals between those two.
Speaker 1: UH.
Speaker 2: Frequency range between upper and lower cutoff is the frequencies bandwidth.
Speaker 2: Opposite of band passes band stop, which is like a
Speaker 2: notch filter. Even those filters past the range of frequencies
Speaker 2: that may attenuate signals in the past band that's called
Speaker 2: insertion loss. All filters are going to have some type
Speaker 2: of insertion loss. The ones I build for my like
Speaker 2: a low pass filter and an LC's.
Speaker 1: They always have.
Speaker 2: It's co could be up to a dB or so
Speaker 2: of loss just going in, so you have to account
Speaker 2: for that in your system design. But and the insertion
Speaker 2: losses is the term for how much you you get
Speaker 2: how much signals lost in the filter itself.
Speaker 1: Outside the past.
Speaker 2: Band attenuation may vary, but maximum attenuation is the ultimates
Speaker 2: the filter's ultimate rejection.
Speaker 1: Okay, another circuits.
Speaker 2: Oscillators they used to consist of an amplifier with the
Speaker 2: feedback from the output to the input.
Speaker 1: The product of.
Speaker 2: Gain and feedback ratio must be greater than one at
Speaker 2: the frequency of oscillation, and this is the basic building block,
Speaker 2: basic premise of all the osc layers we use in
Speaker 2: our radio equipment.
Speaker 1: You've got an.
Speaker 2: Amplifier with feed some of it back to itself, and
Speaker 2: it starts to oscillate. An ostlator consists of an amplifier
Speaker 2: that increases signal amplitude gain and feedback circuit to route
Speaker 2: some of the amplifier's output back to the input. Oscillator
Speaker 2: circuits may include a filter so that feedback is present
Speaker 2: at only the intended frequency. The oscillator output frequency can
Speaker 2: be fixed or variable. An LC oscillator feedback circuit consists
Speaker 2: of an inductor and a capacitor in parallel or series
Speaker 2: that form a resonant circuit, often called a tank circuit
Speaker 2: because of their ability to store energy. The resonant frequency
Speaker 2: of an LC circuit, determined by its values, is the
Speaker 2: frequency of the oscillator. The output frequency of a variable
Speaker 2: frequency oscillator VFO can be adjusted by changing the L
Speaker 2: or C. VFOs are used to tune a radio to
Speaker 2: different frequencies. Two other widely used VFO circuits are the
Speaker 2: phase lock loop PLL in the direct digital synthesizer DDS.
Speaker 2: The DDS is controlled by software. It's comparably stable. The
Speaker 2: crystal oscillators used as the high stability VFO and most
Speaker 2: current transceivers, most of them have a DDS in them.
Speaker 2: These days, mixers can change signals from one frequency to another.
Speaker 2: A mixer circuit combined signals with two frequencies F one
Speaker 2: and F two and produces signals with the sum in difference.
Speaker 1: Frequencies at at its out at its output. And that's
Speaker 1: a term called header dining.
Speaker 2: Example, if I've got a frequency of fourteen point oh
Speaker 2: five megahertz and an F two of three point three five,
Speaker 2: I'm going to get the gain in difference of those
Speaker 2: two frequencies, so i would have a frequency of fourteen
Speaker 2: point five to three and fourteen point oh two six.
Speaker 2: A multiplier similar to a mixer. It creates a harmonic
Speaker 2: of the input frequency. Multipliers are often used when a
Speaker 2: stable VHF or UHF signal is required that cannot be
Speaker 2: generated directly at VHF or UHF low frequency oscillator supplies
Speaker 2: the multiplier input and the output is tuned to the
Speaker 2: desired harmonic of the output signal. Also used in FM
Speaker 2: transmitters use a lot there modulators. A modulator adds any
Speaker 2: information to a carrier signal by varying the carrier's amplitude,
Speaker 2: frequency or phase. It can be used for AM FM
Speaker 2: for single sideband amplitude modulation, there's three types of AM
Speaker 2: three types of AM signals. Full AM has both the
Speaker 2: sidebands and the carrier. The carrier is represented by the
Speaker 2: vertical line in the middle of the sidebands over here,
Speaker 2: and the sidebands contain data, can't contain speech or data,
Speaker 2: and the signals have been used to can't have been
Speaker 2: used to modulate the carrier. Double sideband removes the carrier
Speaker 2: is gone, but has the same bandwidth and information in
Speaker 2: it that the full AM signal had in it. And
Speaker 2: then the single sideband removes one of the sidebands and
Speaker 2: the carrier. And this is the lowest bandwidth of the
Speaker 2: three and also the lowest amount of power that you need.
Speaker 2: Double sideband can be produced by by balanced modulator, which
Speaker 2: is a special mixer, where F one is the carrier
Speaker 2: and F two is the modulator. Single sideband is generated
Speaker 2: by removing the unwadded side unwanted sideband and carrier and
Speaker 2: carrier with a filter or by combining signals with certain
Speaker 2: phase relationships called the phasing method. So there's a filtered
Speaker 2: method and phasing method to remove the unwanted sideband using
Speaker 2: only one sideband uses users transmitted output power more effectively.
Speaker 1: UH.
Speaker 2: Here's a here's a diagram of a frequency or phase modulation.
Speaker 2: You have a reactant modulator, you have an oscillator audio input,
Speaker 2: and this will generate to your double sideband output audio input.
Speaker 2: Here react its modulator, an oscillator in, and you get
Speaker 2: the phase modulated out frequency modulation. The signal frequency varies
Speaker 2: in proportion to modulating the signal's amplitude. It's called deviation.
Speaker 1: UH.
Speaker 2: Phase modulation. Just the deviation varies with both amplitude and
Speaker 2: frequency of the modulated signal produced by reactance modulator connected
Speaker 2: to a tuned or if amplifier following the oscillator. When
Speaker 2: modulation is applied, the phase of the carrier will will
Speaker 2: not not be changed, but the average frequency will not.
Speaker 2: It's going to read that again. When modulation is applied,
Speaker 2: the phase of the carrier will be changed, but the
Speaker 2: average frequency will not change, okay, and the sound identical
Speaker 2: on the air. If you listen to frequency modulation or
Speaker 2: phase modulation, they would sound the same all about the
Speaker 2: detector also called IQ modulation because of the I in
Speaker 2: Q signals that create the modulated output signal that this
Speaker 2: is quadrant quadrature modulation. This is used to transmit digital signals,
Speaker 2: but different combinations of im q signals can create signals
Speaker 2: with any form of modulation. The RF output of the
Speaker 2: combiner consists of a pair of modulated signals that have
Speaker 2: carrier signals ninety degrees different in phase. Widely used in
Speaker 2: software defined radios, which traditionally analogs. Components have been replaced
Speaker 2: by programming that is, filtering, modulation and detection.
Speaker 1: That's where you'll.
Speaker 2: Find quadrature modulation. Here's a figure on the right that
Speaker 2: has a block diagram of the I in Q inputs
Speaker 2: of ninety degrees phase shift network in the middle. Quadrature
Speaker 2: simply means phase shifted.
Speaker 1: By ninety degrees.
Speaker 2: Which of the following are basic components of a sine
Speaker 2: wave oscillator.
Speaker 1: Let's see.
Speaker 2: D filtered and amplifier operating in a feedback loop. What
Speaker 2: determines the frequency of an LC oscillator. That'd be the
Speaker 2: inductance and capassitance of the tank circuit. C. Which of
Speaker 2: the following is characteristic of a digitally direct digital synthesizer
Speaker 2: through the stable crystal d barable output frequency with the
Speaker 2: stability of a crystal oscillator. What term specifies a filter's
Speaker 2: attenuation inside its past band? That would be the insertion
Speaker 2: loss A. What is the phase difference between the I
Speaker 2: and q RF signals that software defined radio equipment uses
Speaker 2: for modulation and demodulation, So it's ninety degrees out of phase? B.
Speaker 2: What is an advantage of using IQ modulation with software
Speaker 2: defined SDRs? Appropriate processing? Right? So it allows you to
Speaker 2: with the right processing, you can do a bunch of
Speaker 2: different stuff if you've got the IQ signals. B. Which
Speaker 2: of the following functions is determined by software and a
Speaker 2: software defined radio can be all those can do filtering, detection, modulation,
Speaker 2: all those things digitally. What is the frequency above which
Speaker 2: a low pass filters output power is less than half
Speaker 2: the input power? So that's the cutoff frequency. What term
Speaker 2: specifies a filtered maximum ability to reject signals out of
Speaker 2: its band? That's the maximum? Would be the ultimate rejection.
Speaker 2: The bandwidth of a band pass filter is measured between
Speaker 2: what two frequencies of a band pass built You've got
Speaker 2: to upper and lower, so UH be the upper and
Speaker 2: lower half half power cut off points. A. What emission
Speaker 2: is produced by a reactance modulator connected to a transmitted
Speaker 2: transmitter r F stage? So reactance modulator is used in
Speaker 2: UH phase modulation B. What's another term for mixing of
Speaker 2: two r F signals UH header dining. What is the
Speaker 2: stage in a v h F FM transmitter that generates
Speaker 2: a harmonic of lower frequency signal to reach the desired
Speaker 2: operating frequency. So that'd be a multiplier, right, You're taking
Speaker 2: a lower frequency to get a higher one, so you're multiplying.
Speaker 2: Be multiplier. What combination of a mixer's local oscillator and
Speaker 2: r F input frequency is found in the output? Be
Speaker 2: the sum in the difference member f F plus f
Speaker 2: plus f one F minus f one.
Speaker 1: You know, so some of the difference.
Speaker 2: Now we're gona talk a little bit about CW transmitters.
Speaker 2: Simplest transmitter consists of an oscillator, an amplifier, and a
Speaker 2: means of turning the signal on off or the key
Speaker 2: or key Here a signal. A single crystal oscillator can
Speaker 2: be replaced with a variable frequency oscillator to allow the
Speaker 2: transmitter to be tuned to different frequencies. So here's your
Speaker 2: basic building block. I've got an oscillator, amplifier, and an
Speaker 2: on off switch and an antenna. Okay, By changing the
Speaker 2: frequency of the of the local oscillator, the VFOs can
Speaker 2: now be shifted from band to band, crying a multi
Speaker 2: band transmitter. So now if I've got an oscillator, if
Speaker 2: I can, I can change the frequency of the oscillator,
Speaker 2: in this case through through some crystals or a veriable
Speaker 2: frequency oscillator. Now I've got something I can operate on
Speaker 2: different bands. Substituting those the circuits to create a single
Speaker 2: sideband signal for the VFO creates a multiband. Now you've
Speaker 2: got a single sideband transmitter. You've got a balance modulator,
Speaker 2: you've got some UH bandpass filters, a mixer. Now I'm
Speaker 2: getting more of a radio that can do voice and
Speaker 2: c W voice signals from a micro process by speech
Speaker 2: amplifier input to the balance mixture. This is a single
Speaker 2: sideband phone transmitter. The variable frequency oscillator is the other
Speaker 2: input to the balance modulator. The output is a digital
Speaker 2: single is a double sideband signal, so the filter is
Speaker 2: used to remove the undesired sideband producing in a single sideband.
Speaker 2: So in your modern HF radio, when you switch between
Speaker 2: AM between upper and lower sideband, you either switching you're
Speaker 2: switching in and out one of these filters, so you're
Speaker 2: generating the double sideband, and UH based on upper lower
Speaker 2: sideband is going to select which one of those you're
Speaker 2: going to transmit, so they're both produced in your radio,
Speaker 2: but you FI filter out one the one that you
Speaker 2: want to use. Distortion anywhere in the transmit chain will
Speaker 2: generate unwanted sperienced signals called harmonics or mixing products or splattered.
Speaker 2: An FM transmitter looks like this picture here. I've got
Speaker 2: a microphone, a speech amplifier, reractans modulator, an oscillator, multiplier, filter,
Speaker 2: and amplifier. So the carrier and modulation are generated at
Speaker 2: relatively low frequencies in FM transmitters, and the mosleated signals
Speaker 2: and multiplied to the desired output frequency. The amount of
Speaker 2: signal deviation is also multiplied, so modulation and frequency changing
Speaker 2: are performed differently. In FM transmitters is much more practical
Speaker 2: to generate the signal at low frequency and multiply it
Speaker 2: to reach the high the desired band and an example
Speaker 2: in a two meter FM transmitter, the modulated oscillator frequencies
Speaker 2: approut from the twelve megahertz and multiplies and multipliers select
Speaker 2: the twelfth harmonic The transmission are now put a one
Speaker 2: forty six dot five to two. For example, the oscillator
Speaker 2: must divided by twelve or a twelve point twenty one
Speaker 2: mega hurt signal.
Speaker 1: The frequency deviation is also multiplied.
Speaker 2: For example, if the five two mega hurt signal is
Speaker 2: to have the standard deviation of five megaherts, the maximum
Speaker 2: oscillator deviation would be five divided by twelve or zero
Speaker 2: point four to one six megaherts or four hundred and
Speaker 2: sixteen point seven hurts. Okay, because it gets multiplied along
Speaker 2: with the frequency multiplication for the FM transmission, Carson's rule
Speaker 2: provides a good approximation of FM signals bandwidth. The bandwidth
Speaker 2: is equal to two times the peak deviation plus the
Speaker 2: highest moduling frequency. In our example, if an FM phone
Speaker 2: signal's peak deviation is limited to five killer hurts and
Speaker 2: the highest modulating frequency is three killer hurts. Then bandwidth
Speaker 2: is equal to two times five plus three or sixteen
Speaker 2: killer herts. So bandwidth is equal to two times the
Speaker 2: peak deviation plus the highest modulating frequency. Over signal quality,
Speaker 2: you can overmodulate on AM signals an AM or single
Speaker 2: side bend signal that varies excessively in responding to the
Speaker 2: modulation signal, you'll have distorted transmitted audio. And if you
Speaker 2: speak too loudly, or mike gains too high, or audio
Speaker 2: gains too high, you can have overmodulation and distort your audio.
Speaker 2: Modulation envelope of an AM signal. Look at the signal
Speaker 2: here on the left, very nice, uh looking AM signal.
Speaker 2: You've got the This is the audio right, what's in?
Speaker 2: Here's your modulation frequency. Here's your audio for sequency in
Speaker 2: this particular one, this is a you put in like
Speaker 2: a kill hurts tone. You got a single tone. That's
Speaker 2: what looks very very nice. If I start to overmodulate,
Speaker 2: you'll see there's time share where there's stuff cuts off,
Speaker 2: and I get other spurious signals down there in the
Speaker 2: frequency spectrum. So a is a poorly modulated signal, whoops
Speaker 2: over there at this as a properly modulated signal B
Speaker 2: is an example of a cutoff. Transmitter output is turned
Speaker 2: off instead of following the modulated signal, so it sounds choppy,
Speaker 2: sounds distorted.
Speaker 1: Transmit.
Speaker 2: If you have cut off the transmitter output is turned
Speaker 2: off instead of following the modulated signal. Flat topping occurs
Speaker 2: when the transmitter output reaches a maximum limit. It cannot
Speaker 2: increase further even though the moduling signal is increasing. That's
Speaker 2: why it clips at the top and it stops transmitting.
Speaker 2: It's gonna sound choppy and distorted. If the outputs was
Speaker 2: completely cut off between peaks, the result is called carrier cutoff.
Speaker 2: Both types of overmodulation cause interference by genering spurious signals
Speaker 2: that is, distortion products beyond normal signal bandwidth called splatter
Speaker 2: AD and automatic level control or ALC circuit, and the
Speaker 2: transmitter helps prevent this type of over modulation and reduces
Speaker 2: output power during voice peaks. It's controlled by properly setting
Speaker 2: the transmitted audio or might gain and should be adjusted
Speaker 2: to activate only on your voice peaks. There's a two
Speaker 2: tone test is used to monitor transmitter linearity, which keeps
Speaker 2: a signal clean. It only needs to be performed occasionally
Speaker 2: denote appropriate gain settings and two level adjustments. Two tone
Speaker 2: comes from the use of two non harmonically related harmonically
Speaker 2: related signals for the test. Most radios display carrier frequency
Speaker 2: of a single sideband. Actual signal lies between above the
Speaker 2: upper sideband or low below the lower sideband, so your
Speaker 2: dial frequency is not exactly where your audio starts, it's
Speaker 2: where your carrier would be. Each single sideband occupies three
Speaker 2: killer hurts, so you'll need to stay far away from
Speaker 2: edge from the edge of frequency privileges to avoid ill
Speaker 2: legal transmissions. So for generals using lower sideband on forty meters,
Speaker 2: operate with a career frequency of at least three killer
Speaker 2: hurts above the edge of the band segment. Because remember
Speaker 2: at forty meters for lower sideband, you want to be
Speaker 2: three killer hurts above, so seven point one seven eight,
Speaker 2: because we're allowed to go down to seven point one
Speaker 2: seven five. So that's my low end and I'm on
Speaker 2: lower sideband, I want to put my dial frequency on
Speaker 2: seven point one seven eight. When sidebands extend from the
Speaker 2: carrier toward the band edge or a band segment edge,
Speaker 2: operate with the displayed carrier frequency no closer than three
Speaker 2: killer hurts of the edge of the band, so your
Speaker 2: signal is sure to be cleaned.
Speaker 1: So if I'm on.
Speaker 2: Twenty meters here and I'm upper sideband signal and here's
Speaker 2: the edge of the band, I want to make sure
Speaker 2: I'm less than the edge, so I'm not right up
Speaker 2: against it. I don't want to put my dial frequency
Speaker 2: on fourteen three three fifty because then my upper sidebands
Speaker 2: out of outer band. Here's a forty meter example. It's
Speaker 2: a lower sideband. You want to make sure you're not
Speaker 2: This is the seven point one seventy five is the
Speaker 2: low end general place that we can We can't go
Speaker 2: below that, so you want to make sure you're set
Speaker 2: up above that. At least three kill hurts up above.
Speaker 2: So another circuit speech processing. The average power of an
Speaker 2: AM or single sideband signal is much lower than c
Speaker 2: W when transmitted over HF and AM signal. In the
Speaker 2: presence of noise interference, et cetera, the received signal can
Speaker 2: be difficult to understand. Speech processing increases the average power
Speaker 2: of the signal without the arding it, which results in
Speaker 2: improved intelligibility of the received signal in poor conditions. So
Speaker 2: a lot of the modern radios have speech processing. You
Speaker 2: can try to on or off and it works pretty good,
Speaker 2: but you have to make sure you got it all
Speaker 2: set up right and adjusted correctly. Speech processors can also
Speaker 2: amplify a low level background noise, reducing intelligibility, So careful
Speaker 2: of that, uh CEW key clicks sharp transient clicking sounds
Speaker 2: heard on adjacent frequencies as a transmitter turns on and
Speaker 2: off too rapidly during the cd W transmissions, or if
Speaker 2: transmitter turns on and off erratically, those are called key clicks.
Speaker 2: CWA forms can be inspected using a monitor in a celloscope,
Speaker 2: and you can see what the key clicks would look like.
Speaker 2: Just show one without it, but uh, you know, there's
Speaker 2: a way you can see if you've got key clicks
Speaker 2: going on. And if you've got them, you've got to
Speaker 2: turn down your your modulation a little bit. What control
Speaker 2: is typically adjusted for proper ALC setting on a single
Speaker 2: sideband transmit audio and microphone game? Okay, what signal are
Speaker 2: yoused to conduct the two tone test? Two audio signals
Speaker 2: that are not harmonically related, that's the key non harmonically
Speaker 2: related signals, So that would be be what type of
Speaker 2: transmitter performance does a two tone test analyze linearity is
Speaker 2: usually linearity. How linear it is a What is the
Speaker 2: purpose of a speech processor and a transit transceiver? Increase
Speaker 2: that loudness? Introduce that increase. It's going to be a
Speaker 2: increase the loudness of your transmitted voice signal to the
Speaker 2: other guy. How does a speech processor affect a single
Speaker 2: sideband phone signal? Preass average power? Do not peak power,
Speaker 2: but average power? That's the difference. What is the effect
Speaker 2: of an incorrectly adjusted speech processor all those Yeah, there's
Speaker 2: stormed speech excess in their modulation. A lot of people
Speaker 2: have problems with these digital modes, not adjusting their ALC
Speaker 2: in some of these circuits, and you can really see
Speaker 2: it on a digital mode can cause problem if you
Speaker 2: overdrive it. What frequency range is occupied by a three
Speaker 2: killer hurts lower sideband signal? When the carrier displayed is
Speaker 2: seven point one seven eight, it's going to be seven
Speaker 2: point one seventy five. Right, it's three killer hurts below
Speaker 2: because it's a lower side band. Let's see it tells
Speaker 2: us how to do it. Here we subtract three killer
Speaker 2: hurts from that and we get seven point one to
Speaker 2: seventy five. All right, What frequency range is occupated by
Speaker 2: a three killer hurts signal display with the upper sideband signal. Now,
Speaker 2: so we're going to add so three point three four
Speaker 2: would be B three point three four seven and three
Speaker 2: point three five because we're adding three kill hurts to it.
Speaker 2: And how close to the lower edge of a band's
Speaker 2: phone segment should your display care frequency be with three
Speaker 2: killer hurts wide lower sideband? Okay, at least three killer
Speaker 2: hurts on lower sideband. It means you need to be
Speaker 2: above at least three kill hurts above A. You're not
Speaker 2: at one kill hurts is at least three, so the
Speaker 2: ones are out. It's got be above it's lower, so
Speaker 2: be a BOB and the same thing. If you're on
Speaker 2: using the lower upper sidebands, you need to be below
Speaker 2: three kill hurts below which would be B and which
Speaker 2: are The following describes linear amplifier h our evampire used
Speaker 2: touch damage frequency MULTIPLI B B.
Speaker 1: YEP.
Speaker 2: Amplifier preserves the output and fire which the output preserves
Speaker 2: the input wave form. That's right, you're just taking what
Speaker 2: the AMPHI takes what it's given and transmitted. It preserves it.
Speaker 2: That's what they're talking about. What circuit is used to
Speaker 2: select one of the sidebands from a balance modulator. You
Speaker 2: have upper sideband filter, lower sideband filter. What output is
Speaker 2: produced by a balance modulator? So a balance modulator produces
Speaker 2: a double sideband modulated r D. Which of the following
Speaker 2: is an effect of overmodulation, insufficient audio accessive bandwidth the
Speaker 2: excessive bandwidth. What is meant by the term flat topping
Speaker 2: when referring to an amplitude modulated phone signal?
Speaker 1: Uh?
Speaker 2: Trump probably justice the So it's gonna be C signal
Speaker 2: distortion caused by excessive driver speech level. What is the
Speaker 2: modulation envelope of an AM signal? Bandwidth of the modulated
Speaker 2: modulation envelope, it would have to be a waveform creator
Speaker 2: connecting the peak values of the modulated signals. So what
Speaker 2: is the total bandwidth of an NFM phone transmission having
Speaker 2: five killer hurts deviation and three killer hurts modulation frequency?
Speaker 1: So remember how to do this.
Speaker 2: It's two times that, which would be two times five
Speaker 2: plus three is sixteen. What is the frequency deviation for
Speaker 2: a twelve point two one megas practice modulate oscillator and
Speaker 2: five killer deviation? It's uh, So you're gonna divide, You're
Speaker 2: gonna get about you got to divide by twelve, so
Speaker 2: you're gonna get four hundred and sixteen point seven. Hurts me.
Speaker 2: They're gonna talk about amplifiers. Radio operators HF sometimes use
Speaker 2: amplifiers to boost their signals when conditions are poor to
Speaker 2: accommodate difficult propagation paths.
Speaker 1: On HF.
Speaker 2: High power amplifiers often use vacuum pum circuits that require
Speaker 2: operator adjustment. The efficiency of an amplifier is defined as
Speaker 2: the RF output power divided by the DC input power,
Speaker 2: also called linears. A Class A amplifier the most linear,
Speaker 2: lowest cost signal distortion, at least efficient because class as
Speaker 2: passed the entire sinusoil input signal they conduct one hundred
Speaker 2: percent of the time, so Class A good amplifier but
Speaker 2: least efficient. Class B is known as a push pool amplifier,
Speaker 2: and it's a pair of amplifying devices, each actively active,
Speaker 2: gearing complementary halves of the signals cycle. They have good
Speaker 2: linear good efficiency. Class AB midway between the A and
Speaker 2: B LINEARY is not as good, but efficiency is better,
Speaker 2: and Class C has the highest efficiency, but it's only
Speaker 2: suitable for C W and FM due to poor linearity.
Speaker 2: High efficiency, poor linearity Some leary amplifiers can be operated
Speaker 2: in either Class A B for single sideband operation or
Speaker 2: Class C for C c W. Transceivers often include a
Speaker 2: delay in the king circuit timing so that the changeover
Speaker 2: relay is completely switched before transceiver is allowed to supply
Speaker 2: in the r F current. This prevents hot switching in
Speaker 2: which amplifier is already supplying RF it can destroy the
Speaker 2: relay or other external devices.
Speaker 1: Very important.
Speaker 2: You want to make sure you're your your you switch
Speaker 2: between transmit and receive where your amplifier is connected before
Speaker 2: you start transmit, is you connect before you start transmitting.
Speaker 2: Tuning and driving vacuum tube at amplifiers, So if you've
Speaker 2: got a vacuum tube amplifier, you want to set the
Speaker 2: band switch to your desired frequency. You want to apply
Speaker 2: the drive power to the amplifier while adjusting the tune
Speaker 2: control to obtain minimum plate current. Find you got to
Speaker 2: dip it. You got to dip your plate current. Adjust
Speaker 2: the load then to get the peak power output, and
Speaker 2: continual adjusting until the max power is obtained avoid exceeding
Speaker 2: the maxplate current.
Speaker 1: UH.
Speaker 2: The input power to the amp fire may also be
Speaker 2: adjusted during the process. Tubes can be destroyed by applying
Speaker 2: too much drive. Modern amplifiers have protective circuits. Similar cautions
Speaker 2: apply to solid amplifiers with power transistors that can be
Speaker 2: destroyed with successive power. You've got to be careful that
Speaker 2: the controls are pretty good these days protecting them. Some
Speaker 2: amplifiers generate automatic level control signals that can be connected
Speaker 2: back to the transmitter to limit excess drive. Check both
Speaker 2: the amplifier and the transceiver manuals to be sure that
Speaker 2: they're compatible signals. So you know how to use the
Speaker 2: ALC meter readings, so that that's important. It's pretty standard,
Speaker 2: but you need that. Sometimes there's a nuance there. You
Speaker 2: got to go check that out. So neutralization HF amplifiers
Speaker 2: can self oscillate because of positive feedback, and an amplifier too.
Speaker 2: Self oscillation create spurs outputs. You may damage the tube
Speaker 2: or even the amplifier amplifier components. So the technique to
Speaker 2: prevent this is called neutralization. It's done by creating a
Speaker 2: negative feedback, sometimes a small capacitor between the amplifier output
Speaker 2: and the input circuits, and that's usually built into your
Speaker 2: to your amplifier that they've taken care of that, but
Speaker 2: if you're building your own that's an important that you
Speaker 2: need to have in there. Okay, well, what's the effective
Speaker 2: for plate current of the of the correct setting of
Speaker 2: a vacuum two r F power amplifier's tune control? What's
Speaker 2: the EFFECTA of the plate current UH produced to find
Speaker 2: that dip when.
Speaker 1: You're doing it?
Speaker 2: What's the reason to use ALC with an arm of
Speaker 2: amplifier to produce to prevent excessive drive? See? What is
Speaker 2: the current adjustment for the load or what's the correct
Speaker 2: adjustment for the load or coupling control of the vacuum
Speaker 2: tube power amplifier minimum staid you are plate current to
Speaker 2: see ok B, I think let mean d desired power
Speaker 2: output without exceeding the loud maximumiable plate current. So you're
Speaker 2: trying to get those adjustments to load and coupling controls.
Speaker 2: You trying to balance those two to arrive at that.
Speaker 2: What is the purpose of delaying r F output after
Speaker 2: activating a transmitter's keying line to the external amplifier to
Speaker 2: allow time for the amplifier to switch the antenna between
Speaker 2: the transit transceiver.
Speaker 1: And amplifier, so C.
Speaker 2: What's the purpose of a neutralizing and an amplifier to
Speaker 2: limits modulation and then to cut off to eliminate self postellations. B.
Speaker 2: Which of these class of ampfires has the highest efficiency?
Speaker 2: That would be the C class used for FM and
Speaker 2: morse code CW. In a class A amplifier, what percentage
Speaker 2: of the time does the amplifying device conduct Class A?
Speaker 2: It's one hundred MBA. How is the efficiency of an
Speaker 2: RF amplifier determined the d C r F output power
Speaker 2: by the DC input uh? B.
Speaker 1: That's correct.
Speaker 2: Which of the following modes is a class C power
Speaker 2: stage appropriate for amplifying a modulated signal? Following modes is
Speaker 2: a Class C FM only it's not linear, so single
Speaker 2: sideband or AM you have a distortion on those, So
Speaker 2: film all right, our next section, we're gonna be talking
Speaker 2: about receivers and HF station installation. Talk a little about
Speaker 2: superheader superheader dime receivers. UH. Most receivers used by today's
Speaker 2: amateurs are superheader dying UH. The received signals are incredibly
Speaker 2: weak and on the order of nano or peko watts.
Speaker 2: The received signals are first strengthened by an r F amplifier,
Speaker 2: then applied to the r F of a mixer. The
Speaker 2: local oscillator is adjusted so that the desired frequency creates
Speaker 2: a mixing product at the intermediate. At the intermediate frequency,
Speaker 2: a detector or demodulator stage follows the UH IF the
Speaker 2: IF to recover the moduling information. An input amplifier, gain,
Speaker 2: demodulator stage bandwidth, an input amplifier noise can all affect
Speaker 2: transceiver receiver sensitivity. So the receiver's sensitivity to repeat that
Speaker 2: can be impacted by the amplifier, gain, demodulator stage bandwidth,
Speaker 2: an input amplifier noise. All those together and how you've
Speaker 2: got those set up can affect your receiver's instinctivity. Superheaded
Speaker 2: superheaded nine receiver convert signals to audio and two steps
Speaker 2: the front end right here converts the frequency of the
Speaker 2: signal to an intermediate frequency where most of the gain
Speaker 2: of the receiver where the receiver is provided, A second
Speaker 2: mixer is provided, a second mixer, a second mixer. The
Speaker 2: product detector converts the signal to an audio frequency. So
Speaker 2: you come in here on the front end IF filter
Speaker 2: and another IF amplifier, product detector. Audio comes out here
Speaker 2: on audio amp stage. So you've got two osc layers
Speaker 2: of that's called a beat beat local lost lador in
Speaker 2: a BFO, so it's a two stage conversion superhead dyne.
Speaker 2: Once amplified to a more usable level. Single sideband and
Speaker 2: CW signals are demodulated by a product detector. It's a
Speaker 2: special type of mixer. If an AM signal is being received,
Speaker 2: a product detector or envelope detector recovers the modulating signal.
Speaker 2: Output of the detector is an audio signal amplified by
Speaker 2: the audio frequency amplifier and input to a speaker, headphones,
Speaker 2: or a sound card. The r F amplifier mixer are
Speaker 2: the receivers at The RF amplifier and mixer are the
Speaker 2: receiver's front end. It processes weak signals at the original
Speaker 2: frequencies UH. A pre selector is often used to reject
Speaker 2: out of band signals. A pre amplifier or preamp we
Speaker 2: call it is used if additional sensitivity is needed, such
Speaker 2: as weak signals. The simplest possible superhead consists of a
Speaker 2: mixer connected to the antenna, an oscillator to act as
Speaker 2: a local oscillator, and a detector that operates directly on
Speaker 2: the resulting IF signal. The single frequency IF stage makes
Speaker 2: it much user to create high quality filters and high
Speaker 2: gain amplifiers without having.
Speaker 1: To be tuned.
Speaker 2: Only the lo O needs to be tuned in the
Speaker 2: superhead receiver. Recall the formula for intermodulation mixing of signals.
Speaker 2: You get F one plus F two. For example, to
Speaker 2: convert an RF signal on one twenty five megahertz to
Speaker 2: an IF of four to fifty five, the lo O
Speaker 2: must be tuned to either four point twenty five minus
Speaker 2: four fifty five, which is equal to thirteen point seven
Speaker 2: nine five, or to fourteen point twenty five plus four
Speaker 2: to fifty five, which is equal to fourteen point seven
Speaker 2: oh five. Superheterodynes have some weaknesses, like all radio designs,
Speaker 2: because they are mixing products at both the some and
Speaker 2: difference frequencies. Undesired signals can create their own mixing products
Speaker 2: at the IF uh so we've got got the RF
Speaker 2: input local oscillator, we get the sum and the differences
Speaker 2: of these two. Another flaw is caused by the local
Speaker 2: oscilator and other oscillator circuits. Leakage of signals into the
Speaker 2: signal path can cause steady state signals to appear. Called
Speaker 2: a figure because the next figure shows a single conversion
Speaker 2: with only one mixer converting the signal from the IF
Speaker 2: to the RF. This is the single conversion right here
Speaker 2: r F input one oscillator down single conversion. The IF
Speaker 2: stage provides most of the high gain most of the
Speaker 2: game in selectivity. Filtering is applied at each IF allows
Speaker 2: filter bandwidth selection for the desired signal. This gives the
Speaker 2: best received signal quality with the lowest unwanted noise and interference,
Speaker 2: maximizing the signal to noise ratio. In a mixture with
Speaker 2: an r F input or input frequency F one and
Speaker 2: local loss or F two, remember there are mixing products
Speaker 2: that f one plus or minus f two, meaning the
Speaker 2: sum and the difference of the two. When an L
Speaker 2: with an LO of thirteen point eight megahertz, a mixing
Speaker 2: product of fore fifty five killerhertzer point four to five
Speaker 2: five can be generated by a signal of either fourteen
Speaker 2: point two five five or thirteen point three four five,
Speaker 2: assuming that the intended signal is fourteen point twenty five
Speaker 2: to five meg hurts. An image response is an image
Speaker 2: response similar to AM single sideband and CW superhits. The
Speaker 2: linear IF amplifiers replaced by a limited limited amplifiers limited amplifiers.
Speaker 2: The received signal until all amplified modulated information noise is
Speaker 2: removed and only a square wave of the of the
Speaker 2: varying frequency remains. AUTO information is recovered by a discriminator
Speaker 2: or quadrator detector that replaces the product detector. Once the
Speaker 2: FIM signal is converted to the IF high gain amplifiers
Speaker 2: called limitters change the signal to a square wave that
Speaker 2: only varies in frequency, not amplitude, a discriminator converts the
Speaker 2: frequency variations to audio. So here's a block diagram of
Speaker 2: an FM signal amplifier, mixer I F filter limiter, discriminator,
Speaker 2: and then the audio amplifier itself. For digital signal processing,
Speaker 2: the general term which is a general term for converting
Speaker 2: signals from analog to digital. A DSP system uses an
Speaker 2: analog to digital converter change the signal to a digital data.
Speaker 2: A special type of microprocessor then performs the mathematical operations
Speaker 2: on the data to accomplish filtering, noise reduction, and other functions.
Speaker 2: A digital to analog converter changes the process data back
Speaker 2: to analog form for an audio for to output as
Speaker 2: as audio. Digital signal processing has two advantages over analog circuitry. Performance, flexibility,
Speaker 2: UH DSP offers selectable programmable filters and allow the operator
Speaker 2: to adjust the filter bandwidth and shape, even in shape,
Speaker 2: and even to define new filters. Expensive functions and analog
Speaker 2: circuits can be implemented in DSP as a as a
Speaker 2: program without additional hardware. Just a lot of the modern
Speaker 2: receivers today at radios we buy have DSP circuits in
Speaker 2: them UH and they've come a long way and they
Speaker 2: work very well.
Speaker 1: To manage the the receiver gain or r F gain.
Speaker 2: Looking for weak signals, set RF gain to its maximum
Speaker 2: for highest receiver sensitivity, lower r F gain volume to
Speaker 2: reduce background noise. Automatic gain control AGC circuits very gain
Speaker 2: of the r r F and I have amplifiers, so
Speaker 2: output volume stays constant for both weak and strong signals.
Speaker 2: AGC circuits changes the voltage that controls the IF gain m.
Speaker 2: This voltage is read by the S meter, which measures
Speaker 2: signal strength. S meters are calibrated in S units, so
Speaker 2: one S unit equals up to six dB. Four fold
Speaker 2: is equal to four x change in signal strength S nine.
Speaker 2: A strong signal is located at the midpoint of the display.
Speaker 2: Large values to the right twenty forty and sixty. These
Speaker 2: correspond to dB above S nine. Readings of S nine
Speaker 2: plus twenty dB is a signal twenty dB or one
Speaker 2: hundred times stronger than an S nine signal. Receiver linearity,
Speaker 2: and if the received signal is distorted, spurry signals will
Speaker 2: appear just as if transmitting stations were emitting them. The
Speaker 2: most common form of receiver non linearity is overload, also
Speaker 2: code called front end overload or gain COMPRESSIH. The solution
Speaker 2: to overload is to filter out the fending signal or
Speaker 2: reduce receiver game. It's an attenuator circuit. Proper use of
Speaker 2: attenuator and RF GAG controls can dramatically reduce received noise
Speaker 2: distortion caused by strong signals. So again, a lot of
Speaker 2: our modern amplifiers have some pretty good controls for these
Speaker 2: kinds of things, and if you learn how to use them,
Speaker 2: and you can really help improve your receiver receiver reception. So,
Speaker 2: you know, get out your man you'll look at those controls.
Speaker 2: A lot of folks, you know, we buy these radios,
Speaker 2: have all these cool features and we want to use
Speaker 2: a few of them. But look at your manual. There's
Speaker 2: some really cool things will allow you to really fine
Speaker 2: tune and get your receiver working great. I have filters
Speaker 2: narrow the receiver's pass man They get rid of the
Speaker 2: unwanted signals. Notch filters remove signals and a very narrow
Speaker 2: bandwidth the frequency such as signal tone from an interfering carrier.
Speaker 2: A lot of these, the newer ones and the dogs
Speaker 2: filters are great. They're they're usually it's some kind of
Speaker 2: a digital form now and uh uh they work, they work,
Speaker 2: they work well, so you know, get your manual out,
Speaker 2: figure out how to use this stuff. There's really neat
Speaker 2: things in these.
Speaker 1: Uh.
Speaker 2: On the pass band or if ship adjust receivers passband
Speaker 2: above and below the displayed carrier frequency. So if you've
Speaker 2: got some noise on the if you're on a single
Speaker 2: side of band and have some crash over here noise,
Speaker 2: you can sometimes take that, just move it a little
Speaker 2: bit and get that out of your way.
Speaker 1: Uh.
Speaker 2: And also allowed it keeps you from interfering with the
Speaker 2: other folks. Reverse sideband controls allow switching between received c
Speaker 2: W signals above carrier frequency LSB and below USB and LSB.
Speaker 2: There's some boids interference by placing the signals on the
Speaker 2: other side of the carrier where filtering rejects, So that's
Speaker 2: another technique you can use.
Speaker 1: Uh.
Speaker 2: Some other ways to reduce noise. Noise noise blinkers uh uh.
Speaker 2: They can sense sharp short sharp pulses and the IF
Speaker 2: signal and reduce the gain of the IF and audio
Speaker 2: amplifiers during the pulse. It's called blanking. Adjust your noise.
Speaker 2: Blankers can be set to blank to receive at different
Speaker 2: noise levels, so you have to play around with that.
Speaker 2: They do work. If you have some periodic noise that's
Speaker 2: going on, you can cut that in.
Speaker 1: It works pretty good.
Speaker 2: Noise reduction is performed by the digital signal processors. They
Speaker 2: can remove hiss and noise from the audio that is
Speaker 2: not part of of the desired speech CW. Increasing the
Speaker 2: noise reduction level may cause some of the desired signal
Speaker 2: to be removed, causing distortion. So use the least amount
Speaker 2: when you needed to minimize. You're still intelligibly hear what
Speaker 2: you're trying to hear, so there's a trade off there.
Speaker 2: But they do work fairly well too. And the DSP
Speaker 2: noise reductions have been around for a while and they
Speaker 2: work pretty well. Okay, what's the purpose? Not the notch
Speaker 2: filter found in many HF transceivers to reduce interference carriers in.
Speaker 1: The past band.
Speaker 2: I think that's what is b What is an advantage
Speaker 2: of selecting the opposite or reverse sideband when receiving CW.
Speaker 2: I think C maybe possible reduce eliminate interference from the
Speaker 2: other signals. How does a noise blanker work increases bandwidth? Nope,
Speaker 2: redrects noise points, Nope, reduces gain during the noise pulse.
Speaker 2: Uh C, it's actually reducing the game during the noise
Speaker 2: the noise pulses. What happens as a receiver's noise reduction
Speaker 2: level is increased, received signals may become distorted. I think
Speaker 2: that's what we just said. A. What's the purpose of
Speaker 2: using a received attenuation receive attenuator? A's good one, are.
Speaker 1: There?
Speaker 2: Well, we'd have to be a event receiver overload from
Speaker 2: strong incoming signals. All right, What does an S meter
Speaker 2: measure measures that received signal strength? How does a signal
Speaker 2: that that reads twenty dB over S nine compared to
Speaker 2: one that reads S nine on the receiver assume a
Speaker 2: properly calibrated S meter. Well, if you recall twenty dB,
Speaker 2: if you did an old math will be one hundred times,
Speaker 2: so it's one hundred times more powerful. D how much
Speaker 2: change in a signal strength is typically represented.
Speaker 1: By one S unit? Okay?
Speaker 2: How much must the power output of a transmitter be
Speaker 2: raised to change the S meter reading on a distant
Speaker 2: receiver from S to S eight to S nine?
Speaker 1: Okay?
Speaker 2: So so remember we got we just talked about just
Speaker 2: units six dB, So if I go six dB, what's
Speaker 2: that power? How much power increase did I have? Remember
Speaker 2: it's three dB is two times, so that's six dvs
Speaker 2: so probably four times. So we'll see if it's c
Speaker 2: that's the right answer. How's a product detector used? It's
Speaker 2: a if A receiver to perform frequency h D using
Speaker 2: a single sideban receiver to extract the modulated signal.
Speaker 1: That's correct.
Speaker 2: Which of the following is an advantage of a digital
Speaker 2: signal processor? A filter compared to an analog filter as
Speaker 2: good fewer digital comment? Yeah, A. You can do a
Speaker 2: wide range of things with a DSP filter, different shapes,
Speaker 2: different sizes. You can create things which parameter affects receiver sensitivity.
Speaker 2: All three of those things, the ample fire game, the
Speaker 2: demodulator stage, and the noise figure. All those d which
Speaker 2: figure input is varied or tuned to convert signals of
Speaker 2: different frequencies to an intermediate frequency that would be the
Speaker 2: low cost leader. What's the term for interference from a
Speaker 2: signal at twice the if frequency from a desired signal?
Speaker 2: That would be image response? Why is it good to
Speaker 2: match receiver bandwidth to the bandwidth of the operating mode?
Speaker 2: I think results the best signal of the noise. Absolutely Okay,
Speaker 2: talk about HF signal HF station installation. HF operating with
Speaker 2: longer wavelengths and higher frequency, higher field strengths makes grounding
Speaker 2: and interference control much more important. Now that you're going
Speaker 2: to be a general and down in the HF a
Speaker 2: little more, do you have to pay a little more
Speaker 2: attention to your HF state installation? The general exam focuses
Speaker 2: on three related areas, mobile installations, RF grounding, and RF interference.
Speaker 2: Mobile radios can produce output of about one hundred wats
Speaker 2: that can output one hundred watch requires solid power connections
Speaker 2: capable of supplying twenty amps or more. Solid state radios
Speaker 2: perform unpredictably with input volted drops below the specified minermum
Speaker 2: power output supply power supply range. Best power connection is
Speaker 2: a direct connection to the battery with heavy gauge wire
Speaker 2: with both of the leads fused. So mobile mobile installation
Speaker 2: connected it in your car, go direct it to your battery.
Speaker 2: If you can use heavy gauge wire, use both the wires.
Speaker 2: Don't use a cigarette lighter or auxiliary circuit socket usually
Speaker 2: greater for just a few ampsh and they're insufficiently insufficient
Speaker 2: to supply the power needed for one hundred watt radio
Speaker 2: UH stalks. If you have an older, older models like
Speaker 2: before the nineteen eighties or so, they were usually a
Speaker 2: little more robust, but the newer ones they've reduced the
Speaker 2: power on the cigarette lighter output. UH all right, hey,
Speaker 2: mobile installations a limited UH limitation of mobile installations is
Speaker 2: electrically short. A smaller in terms of wavelength, antennas are
Speaker 2: less efficient than full sized ones, particularly on the lower
Speaker 2: frequency bands. Some tips to improve the antenna performance UH
Speaker 2: use the most efficient antenna. You can make sure your
Speaker 2: ground connections are solid. Mount the antenna where it's clear
Speaker 2: for metal surfaces. H. Mobile interference different interference sources than
Speaker 2: home stations. UH. When you're when you're when when you're mobile,
Speaker 2: you got the ignition noise uh uh, spark plugs firing.
Speaker 2: You know, if you've got a diesel engine car, A
Speaker 2: lot of things that can cause noise, the alternator, wine,
Speaker 2: your vehicle, accessories, onboard control computers, electric motors, fuel pumps, windows,
Speaker 2: those are all sources of interference. Winches if you have
Speaker 2: a four x four with a winch on the front,
Speaker 2: so just be careful those things. Grounding and bonding AC
Speaker 2: grounding the bench had voltage from appearing on equipment chassis,
Speaker 2: breaking them shock hazard. To manage r F bond equipment
Speaker 2: enclosures together. Bonding means to connect two points together to
Speaker 2: minimize voltage differences between them during digital operation. Unwanted r
Speaker 2: F currents can cause distortion erradic operation of computer interfaces
Speaker 2: and activate transmitters improperly and garble digital protocols, so bonding
Speaker 2: and grounding can help eliminate some of those issues. Here's
Speaker 2: an example of a typical bonding of RF components in
Speaker 2: your shack. That you want to keep all the equipment
Speaker 2: at the same RF, the same RF voltage, the same potential.
Speaker 2: So in this case here he's got a solid copper
Speaker 2: bus short straps between each of the pieces of equipment
Speaker 2: and then you've got a single point ground somewhere. This
Speaker 2: is a good check. This is a good set up.
Speaker 2: I have a similar setup at my station. Been working
Speaker 2: pretty well here lately. So of courks are pretty good.
Speaker 2: Connect all metal equipment enclosures directly together to a common
Speaker 2: RF bonding bus. Keep connections and keep connections straps and
Speaker 2: wire short. You don't want them to be electrically a
Speaker 2: wavelength of something that you're using, or it will be
Speaker 2: a be an antennae, So you short heavy inductors fourteen
Speaker 2: and twelve gage wires or strap strap best.
Speaker 1: If you can.
Speaker 2: If strong RF is present, use a piece of wide
Speaker 2: flashing or screen under the equipment connected to the bonding bus.
Speaker 2: Sometimes that will work. If ground connection is resonant at
Speaker 2: an odd number of quarter wavelengths, it will generate high
Speaker 2: impedants which enables r F voltages or enclosures and cables
Speaker 2: on those devices, So try to avoid, you know, wavelengths
Speaker 2: of of what you're trying to operate on, for g
Speaker 2: links of cables. Ground loops are created by a continuous
Speaker 2: current path around the series of equipment connections. Loop acts.
Speaker 2: Loops acts as a single conductor turn conductor picks up
Speaker 2: voltages from magnetic fields from transformers, et cetera. So you know,
Speaker 2: if you hear if a result, this can result in
Speaker 2: a hum in a transmitted signal. They interference with control
Speaker 2: or data signals. If you see your station operating erradically,
Speaker 2: check for ground loops and those kinds of things. Ground
Speaker 2: loops can be avoided by connecting all the ground conductors
Speaker 2: to an r F bonding bus like we've shown in
Speaker 2: the picture before, just one path. Try to avoid loops
Speaker 2: if you can. Here's some causes and some solutions for
Speaker 2: r if I.
Speaker 1: Uh, you know, some solutions things are like.
Speaker 2: R F chokes. You can put r F chokes on
Speaker 2: wires online. You can put low pass filters on transmitters
Speaker 2: outputs if you have to.
Speaker 1: You know, just.
Speaker 2: Just go through each of these things and try to
Speaker 2: figure out what's going on. Ask you, ask your your
Speaker 2: your your friend who's a ham Maybe they can help
Speaker 2: to But usually if you get your bonding and grounding right,
Speaker 2: you're gonna do pretty good. So radio frequency interference r
Speaker 2: if I. What are some symptoms? It varies. Interference consists
Speaker 2: of on off buzzes or humming or clicks. If you
Speaker 2: hear that when you're operating CW or f M or
Speaker 2: data uh UH equipment, you can direct detection. You'll hear
Speaker 2: I call RF rectification on a speaker or something of you.
Speaker 2: You're you're you're transmitting, but you're hearing us squawking out
Speaker 2: of a speaker in your room. Uh. That can happen UH.
Speaker 2: Single sideband voice similar to AM, but voice sounds garbled
Speaker 2: or distorted. Things you can do to help prevent that
Speaker 2: is UH. You can install some filters. UH. You can
Speaker 2: put chokes or use a fair right core core for
Speaker 2: conductors carrying R current UH to r F choke by
Speaker 2: winding it around through a faire course. You can do
Speaker 2: some things by taking a table uh wire or have
Speaker 2: these clamp on things at work and you sort of
Speaker 2: have to play with them based on what your artified
Speaker 2: interferences all right Beads placed on cables to prevent artf
Speaker 2: common mode from flowing on the outside of the cable
Speaker 2: to shields is A is another way to try to
Speaker 2: suppress or ified interference to audio equipment and sensor connections
Speaker 2: can be limited by using small capacitors one hundred pe
Speaker 2: code of nanofared size across balanced connections mm hmm. Which
Speaker 2: of the following might be used in reducing ARTIF interference
Speaker 2: to audio frequency devices bypassed capacitory? Which of the following
Speaker 2: could be a cause of interference covering a wide range
Speaker 2: of frequencies. Let's see arcing port electrical connection.
Speaker 1: UH see.
Speaker 2: What sound is heard from an audio device experience ARTF
Speaker 2: interference from a single sideband phone transmitter, A steady hum
Speaker 2: transmitters on the air on off, It will be just uh,
Speaker 2: just distorted speech is the big one. What sound is
Speaker 2: heard from an audio device experiencing r F interference from
Speaker 2: the c W uh give some clicking sounds on off?
Speaker 1: Clicking sounds?
Speaker 2: A h was was a possible cause of high voltage
Speaker 2: that produces r F burns. A round wire has high
Speaker 2: impedance on that frequency. What is the possible effect of
Speaker 2: a resonant ground connection yep, The r F usus can
Speaker 2: can can flow on top of on the enclosures of
Speaker 2: the equipment itself. Which of the fine would reduce r
Speaker 2: F interference caused by common mode current on an audio cable?
Speaker 1: Fair right choke on the cable?
Speaker 2: Uh A, How does the how how can the effects
Speaker 2: of brown loops be minimized. UH bond all equipment equipment
Speaker 2: enclosures together.
Speaker 1: Yep D.
Speaker 2: What could be a symptom caused by a ground loop
Speaker 2: in your station's audio connections home on your station and
Speaker 2: receives equipment draws A which technique helps to minimize RF
Speaker 2: hotspots in an amateur station? A binding all equipment together
Speaker 2: ce Why must all metal enclosures of station equipment be grounded?
Speaker 2: Bon fuse sures hazards voltages don't appear on the chassis. D.
Speaker 2: Which of the following direct uh fused power connection would
Speaker 2: be used for one hundred WAT mobile installation the battery
Speaker 2: using heavy gauge wire. It would be a directly to
Speaker 2: the battery with heavy gauge wire if you can. How
Speaker 2: should DC power for one hundred watt HF transceiver or
Speaker 2: not be swashed? Should it not be connected to a
Speaker 2: vehicle's auxiliary power socket? Uh socket may be inadequate for
Speaker 2: the current draw by the transceiver. B Which of the
Speaker 2: fining most most limits in HF mobile installation? UH I
Speaker 2: think efficiency of the electrically short antenna s C. Which
Speaker 2: of the filing may cause receiver receive interference in a
Speaker 2: radio installed in a vehicle, battery charging system, fueled, the
Speaker 2: lever system, controller, the computers, all those things. How does
Speaker 2: a farerite beat or co or core reduce common mode
Speaker 2: r F current on the shield of a collect cable
Speaker 2: uh A, creating an impedance in the current path. Which
Speaker 2: intermodulation products are closest to the original signal frequencies? Uh
Speaker 2: it's the odd order ones to see, Yes, what produces combination?
Speaker 2: What what process can binds two signals in a linear
Speaker 2: circuit or connection to produce unwanted spurious outputs on linear
Speaker 2: So that would be intermodulation. Which of the following is
Speaker 2: an odd order intermodulation product of frequencies F one and
Speaker 2: F two. I think that's going to be odd order intermodulation.
Speaker 2: Would b c F two F one and that minus
Speaker 2: f twoeh two times the fundamental minus F two.
Speaker 1: Gives you that one.
Speaker 2: So there's how you calculate. Man, Remember the intermodulation first
Speaker 2: to mixing products. The auto order modulation refers to harmonics
Speaker 2: as audo order homo extra closesturing to the second harmonic
Speaker 2: of F one the frequency of the second harmonic two
Speaker 2: F That I just answers C that's correct.