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