[Information] : Where a question shows [Information]. All the information given below that question is OK
In an ordinary hf transmitter the oscillator stage is normally followed by _______
amplifier
bridge
filter
buffer
What would prevent thermal runaway of a transistor amplifier?
bleed resistor
bias stabilization amplification
decoupling capacitor
zener diode
The main LC oscillators are the Hartley and the…
davidson
colpitts
marconi
faraday
In AM, the ration of the modulating voltage over the carrier voltage is _______
Modulation Ratio
Modulation difference
Modulation Index
Modulation Graph
Common Base Transistor Amplifier : [Information]
.... Input Impedance Low Output Impedance Very High Voltage gain High Current gain Low Power gain Low
Common Base Amplifier, the Base terminal is common for both input and output. Input is applied to the Base-Emitter junction and output is taken from Base-Collector junction.
Common Emitter Transistor Amplifier : [Information]
.... Input Impedance Medium Output Impedance High Voltage gain Medium Current gain Medium Power gain Very High
Common Emitter Amplifier, the Emitter terminal is common for both input and output.... Input is applied to the Base-Emitter terminal and output is taken from Emitter-Collector terminal.
Common Collector Transistor Amplifier: [Information]
.... Input Impedance High Output Impedance Low Voltage gain Low Current gain High Power gain Medium
Common Collector Amplifier, the Collector terminal is common for both input and output.....Input is applied to the Base-Collector junction and output is taken from Emitter-Collector junction.
Class C amplifiers are normally biased
greater than the cut off value
less than the cut off value
before the cut off value
after the cut off value
In a transistor circuit, the ratio of the common base emitter current to collector current is called
alpha
bravo
charlie
delta
The change in plate current, divided by the change in grid voltage, keeping the plate resistance constant, is a vacuum tube characteristic known as
vacuum resistance ratio
Grid transfer
Transfer value
Transconductance
Suppressor grids are found in this type of vacuum tube
triode
pentode
diode
tetrode
Determine the resonant frequency of a tuned circuit whose inductance is 150 micro Henrys, and capacitance equal to 150Pf
1.026MHz
2.145Mhz
0.500Mhz
3.690Mhz
What is the voltage regulation of a power supply if the no load voltage is 1kv and the full load voltage is 1.2KV?
An operational amplifier (or an op-amp) is an integrated circuit (IC) that operates as a voltage amplifier....An op-amp has a differential input....That is, it has two inputs of opposite polarity. ...An op-amp has a single output and a very high gain, which means that the output signal is much higher than input signal....It is designed designed to be used with external feedback components such as resistors and capacitors between its output and input terminals
An operational amplifier connected as a filter always utilises...negative feedback
The input impedance of an operational amplifier is generally...very high
The magnification factor of a tuned circuit is also know as
the X of the circuit
the N of the circuit
the Z of the circuit
the Q of the circuit
Match the following characteristics of a class B amplifier:
biased before cut off
biased at cut off
biased after cut off
biased before and after cut off
In AM, the Modulation Index ranges from
0 to 1
0 to 2
0 to 3
0 to 4
Since noise phase-modulator the FM wave, as the noise sideband frequency approaches the carrier frequency the noise amplitude
is decreased
is increased
is attenuated
is filtered
One of the advantages base modulation has over collector modulation of a transistor class C amplifier is :
the lower modulating power required.
the higher modulating power required.
is attenuated
is filtered
A semi conductor diode maybe used as a rectifier because it offers:
small size
rectified voltage
high resistance in one direction and low in opposite direction.
no resistance in both directions
In a radio transmitter energy for producing the continuous radio wave is generated by
electrons
capacitor
local input circuit
oscillator
The local oscillator of a broadcast receiver is tuned to a frequency higher than the incoming frequency to allow
adequate frequency coverage without switching
music to be received
higher rate of frequency detection
one oscillator can be used
The mixing of signal and oscillator frequency in radio receivers produces_____
middle frequency
beat frequency
lower frequency
higher frequency
A low ratio of the AC to DC load impedance of a diode detector results in
positive peak-clipping
cleaner audio
balance peak-clipping
negative peak-clipping
In low level AM system the amplifier following the modulated stage must use_____
linear devices
buffer stage
stable power supply
mixer stage
A keyer is used for _________
lock the door
CW operation
typing
switching
To prevent thermal runaway of transistor amplifiers, there must be
zener diode stabilized
capacitor stabilized
emitter stabilization.
bias stabilization.
Name a circuit that is likely to be found in all types of receivers ?
an audio amplifier
speaker circuit
power supply amplifier
power connecting cord
A transceiver is a __________
allows broadcast stations to be heard
audio receiver filter
transmitter and receiver combination
receiver and speaker combination
FET (Field Effect Transistor) : [Information]
FET input impedance is very high
If a FET is used as a first AF amplifier in a transistor receiver, this will have the effect of reducing effect of negative peak clipping
The function of a tuner is ________
tune for weak signals
audio filter
bandpass limiter
selects only the desired signal
FET Common Source Amplifier [Information]
These devices have a high input impedance along with a low noise output making them ideal for use in amplifier circuits that have very small input signals
The main advantage of a FET used for amplification is that it has very high input impedance and low output impedance.
Three point tracking is achieved with the
capacitor and variable resistor combination
three inductors in series
padder capacitor
tuner
When a receiver has a good blocking performance, this means that
the antenna is a good match
it is unaffected by AGC derived from near by transmission
the receiver has a good ground connection
the receiver has an attenuator fitted
What type of RF receiver does not require an oscillator ?
tuned radio frequency
broadband
frequency depended receiver
receiver using diodes
What do you call the system of modulation where the amplitude of the carrier is made proportional to the instanteous amplitude of the modulating voltage ?
pulse moduation
digital modulation
carrier modulation
amplitude modulation
A device used to connect antenna to the output tank circuit of a transmitter in order to prevent the dc supply from reaching the antenna ?
buffer limiter
antenna coupler
dc supply filter
inductance circuit
Detectors are found in ______
radio rectifiers
radio transmitters
radio receivers
radio antennas
A superheterodyne receiver intended for AM reception, what stage combines the received radio frequency with energy from a local oscillator to produce an output operating at the receiver’s intermediate frequency ?
the mixer
the balance circuit
the beat oscillator
the tuner circuit
In a SSB transmitter one is most likely to find a ______
Class C RF amplifier
Class A RF amplifier
Class B RF amplifier
Class AB RF amplifier
To prevent overloading of the IF amplifier in a receiver, one should use:
squelch
variable selectivity
filter
variable sensitivity
To provide two or more voice circuits with the same carrier, it is necessary to use_____
ISA (Intermediate Sideband)
ISB (Intermediate Sideband)
ISC (Intermediate Sideband)
ISD (Intermediate Sideband)
What stage in the transmitter of a satellite earth station do you see a klystron tube ?
radio frequency amplifier
final amplifier
intermediate amplier
secondary amplifier
In a radio detector
the amplification is zero
the circuit is an acceptor device
the linearity is worse than in a phase discriminator
the power supply essential
In a filter-type SSB transmitter, what stage combines radio frequency and audio frequency energy to produce a double side-band suppressed carrier signal ?
the balanced modulator
the linear circuit
the amplified stage
signal modulator
When the modulating frequency is doubled, the modulation index is involved and the modulating voltages remains constant, the modulation system is _______
detection modulation
bias modulation
phase modulation
frequency modulation
A receiver has poor IF selectivity. It will therefore also have poor________
filtering
audio
blocking
sensitivity
A typical squelch circuit ____
switches the power off
attenuates the signal
cuts off the audio amplifier when the carrier is absent
reduces the power output
That part of the transmitter which determines the operating frequency is the____
oscillator
tuning circuit
power amplifier
R-L-C circuit
Modulation in stages previous to the final radio frequency amplifier is called ________
booster amplification
frequency modulation amplifier
high level modulation
low level modulation
In the spectron of a frequency modulated wave, the amplitude of any sideband depends on the _____
modulation index
frequency index
amplifying index
sideband amplification index
The image frequency of a superhetrodyne receiver is not rejected by the
RF tuned circuit
AF tuned circuit
IF tuned circuit
MF tuned circuit
Superheterodyne Receiver [Information]
In superheterodyne receivers, the incoming RF signal is converted to a fixed Intermediate Frequency (IF) by the local oscillator and mixer, receiver selectivity and gain are determined at this fixed frequency.
Power Supply : Most power supplies are made up of four basic sections: Transformer, Rectifier, Filter, and Regulator [Information]
The Transformer serves two primary purposes: (1) to step up or step down the input line voltage to the desired level and (2) to couple this voltage to the rectifier section.
The Rectifier converts the ac signal to a pulsating dc voltage.
The Filter is used to convert the pulsating dc voltage to filtered dc voltage.
The Regulator maintains the output of the power supply at a constant level in spite of large changes in load current or in input line voltage.
Audio Filter [Information]
A external audio filter is a way to add narrow audio filtering to the audio output of any transceiver or receiver, the audio filter is usually placed between the audio output from the transceiver phone socket and the operators headphones or an external speaker, using an audio filter also reduces qrm/qrn.
Audio filters are classified as follows 1) Active Filter 2) Passive Filter 1) Active Filter - The active filters are designed using active components like transistors or operational amplifiers. The transistors or operational amplifiers require a DC power source for their biasing. 2) Passive Filter - A passive filter is designed using passive components like resistor and capacitor or resistor and inductance.These filters do not require any power source for their operation that why they are called Passive Filters.
Passive components are those circuit devices which can only reduce the electrical power applied to them and not increase it
The three main passive components used in any circuit are the: Resistor, the Capacitor and the Inductor. All three of these passive components have one thing in common, they limit the flow of electrical current through a circuit but in very different ways.
Detector (radio) : In radio, a detector is a device or circuit that extracts information from a modulated radio frequency current or voltage : [Information]
The process of recovering information signal from received carrier is known as detection
In an FM receiver the detector turns the frequency changes back to amplitude changes. This device is usually called discriminator.
Product detector is a type of demodulator used for AM and SSB signals, where the original carrier signal is removed by multiplying the received signal with a signal at the carrier frequency (or near to it)
Phase detector is a nonlinear device whose output represents the phase difference between the two oscillating input signals
Receiver - Selectivity [Information]
Selectivity is a measure of the performance of a radio receiver to respond only to the radio signal it is tuned to (such as a radio station) and reject other signals nearby in frequency, such as another broadcast on an adjacent channel.
The ability of a receiver to separate signals close in frequency is called its:Selectivity
Receiver - Sensitivity [Information]
Receiver Sensitivity- It is the smallest possible signal power level at the input of a receiver which assures proper functioning of a wireless receiver i.e. it will decode data correctly.
Q : What is the limiting condition for sensitivity in a communications receiver? A : The noise floor of the receiver.
Receiver - Dynamic Range : [Information]
The dynamic range of a radio receiver is essentially the range of signal levels over which it can operate.
The dynamic range of an amplifier or receiver is the input power range over which it produces a useful output.
Q: What is the term for the ratio between the largest tolerable receiver input signal and the minimum discernible signal? A: Dynamic range.
Receiver - Noise Figure
Q: What is the noise figure of a receiver? A: The ratio in dB of the noise generated by the receiver to the theoretical minimum noise.
Q: What is meant by the term noise figure of a communications receiver? A: The level of noise generated in the front end and succeeding stages of a receiver.
Class A, B, C and AB Amplifiers : [Information]
Class A amplifier − The biasing conditions in class A power amplifier are such that the collector current flows for the entire AC signal applied.
Class B amplifier − The biasing conditions in class B power amplifier are such that the collector current flows for half-cycle of input AC signal applied.
Class C amplifier − The biasing conditions in class C power amplifier are such that the collector current flows for less than half cycle of input AC signal applied.
A power supply is to supply DC at 12 volts at 5 amperes. The power transformer should be rated higher than____
17 watts
receiver
transceiver
SWR meter
Which of these usually needs a heavy duty power supply?
antenna switch
receiver
transceiver
SWR meter
The diode is an important part of a simple power supply because it converts AC to DC [Information]
A diode is a discrete component that allows current to flow in one direction only.
It is a polarised component with two leads, called the cathode and the anode. The cathode is normally marked with a silver or coloured band or the symbol -
If the anode is connected to a higher voltage than the cathode, current will flow from anode to cathode. This is called forward bias.
If the diode is put in the circuit back to front, so that the voltage at the cathode is higher than the voltage at the anode, the diode will not conduct electricity. This is called reverse bias.
Crystal Oscillator : [Information]
A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a precise frequency.
Crystal oscillators have very high frequency stability.
Piezo-Electric effect is the property of a crystal by which an electrical charge produces a mechanical force by changing the shape of the crystal and vice versa, a mechanical force applied to the crystal produces an electrical charge.
Digital Frequency Counter [Information]
Frequency counters are digital devices for accurate measurement and display of square wave and pulse input signal frequencies. A frequency counter is an electronic instrument used to measure frequency and time. Frequency counters are designed to work on a wide range of radio frequencies.
Flip-Flop : [Information]
A flip-flop or latch is a circuit that has two stable states and can be used to store state information. A flip-flop is a bistable multivibrator. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs
The term flip – flop is used as they can switch between the states under the influence of a control signal (clock or enable) i.e. they can ‘flip’ to one state and ‘flop’ back to other state.
Types of flip flop R-S flip flop D flip flop J-K flip flop T flip flop
The most commonly used filters in SSB generation are:
mechanical filter
low pass filter
band pass filter
crystal filter
Characteristics of each class of amplifier: [Information]
Class A : High fidelity
Class B : Biased at cut off
Class C : High efficiency
An electrical circuit has two 40 milliHenrys (mH) inductors connected in series, this series combination is connected in parallel to another inductor whose value is 80mH. What is the equivalent inductance of the circuit ?
20mH
Class B : Biased at cut off
Class C : High efficiency
In an electrical circuit R1 (100 ohm) and R2 (300 ohm) are connected in series with 240V source is connected across the combination. The total resistance is __________
100 ohms
200 ohms
300ohms
400 ohms
As question 71 what is the total current ?
0.6A
0.8A
1.0A
1.2A
As question 71 the total watts ____
120 watts
144 watts
210 watts
300 watts
A multivibrator is an electronic circuit used to implement a variety of simple two-state devices such as relaxation oscillators, timers and flip-flops. It consists of two amplifying devices (transistors, vacuum tubes or other devices) cross-coupled by resistors or capacitors.The three multivibrator types are: [Information]
astable
monostable
bistable
The modulation index of AM wave is changed from 0 to 1. The transmitter power is ______
increased by 25 percent
Digital Frequency Divider :
A frequency divider, also called a clock divider or scaler or prescaler, is a circuit that takes an input signal of a frequency, fin and generates an output signal of a frequency: fout = fin / n where n is an integer
What is a crystal-controlled marker generator? [Information]
A high-stability crystal oscillator that generates a series of reference signals at known frequency intervals and used to determine the frequency of a receiver.The crystal calibrator can be checked with WWV to make sure that it is accurate.
A crystal calibrator puts out a marker signal at a precise frequency which a radio receiver is tuned to, in order to help derive a correct frequency of interest....When switcheded in the marker generator might be able to generate harmonics every 1 MHz, 100 kHz or 10 kHz depending on a switch setting.
Q : What is one purpose of a marker generator ? A : To provide a means of calibrating a receiver's frequency settings.
Q : What additional circuitry must be added to a 100-kHz crystal-controlled marker generator so as to provide markers at 50 and 25 kHz? ... A : Two flip-flops
The stages in a simple telegraphy (cw) transmitter [Information]
Master (Crystal) Oscillator
Buffer Amplifier
Power (Linear) Amplfier
Morse Key
Radio Transmitter [Information]
Oscillator: Creates alternating current at the frequency on which the transmitter will transmit. The oscillator usually generates a sine wave, which is referred to as a carrier wave.
Modulator: Adds useful information to the carrier wave. There are two main ways to add this information. The first, called amplitude modulation or AM, makes slight increases or decreases to the intensity of the carrier wave. The second, called frequency modulation or FM, makes slight increases or decreases the frequency of the carrier wave.
Amplifier (RF) : Amplifies the modulated carrier wave to increase its power. The more powerful the amplifier, the more powerful the broadcast.
Antenna: Converts the amplified signal to radio waves.
Mixer : RF (Radio Frequency) mixing enables signals to be converted to different frequencies and thereby allowing the signals to be processed more effectively : [Information]
The function of a frequency mixer in a super heterodyne receiver is that it mixes or multiplies the incoming modulated carrier with the locally generated carrier (LO), it then produces a number of frequencies. The produced frequencies are either the sum or the differences of the frequencies of the received signals.
Local Oscillator (LO) is an electronic oscillator used with a mixer to change the frequency of a signal. This frequency conversion process, also called heterodyning, produces the sum and difference frequencies from the frequency of the local oscillator and frequency of the input signal.
It is found that if two signals are passed through a non-linear circuit, then additional signals on new frequencies are formed. These appear at frequencies equal to the sum and difference frequencies of the original signals. In other words if signals at frequencies of f1 and f2 enter the mixer, then additional frequencies of (f1+f2) and (f1-f2) will also be seen at the output.
Example : If the RF frequency f1 is 1Mhz and Local Oscillator Frequency f2 is 1.5MHz are mixed together then additional frequencies of (f1+f2) :1MHz + 1.5MHZ = 2.5MHz and (f1-f2) : 1Mhz - 1.5MHz = 0.5 MHz will be seen at the output......
Filters:A filter is an electric circuit (often called a network) that allows certain frequencies to pass but rejects (attenuates) other unwanted frequencies.
In general, filters are one of four types - Lowpass (LPF), Highpass (HPF) and Bandpass (BPF) and Bandstop. [Information]
Low Pass Filter is designed to pass low frequency signals and to block those above a certain design frequency. In ham radio these are typically used to block VHF harmonics of HF transmissions that interfere with TV reception.
High Pass Filters allow the transmission of high frequency transmissions and block frequencies below the design frequency.
Band Pass Filters allow a specific band of frequencies to pass and block all those above and below. These are typically used in repeater installations to "notch" the frequency of the repeater and reject all unwanted frequencies.
A band-stop filter or band-rejection filter is a filter that passes most frequencies unaltered, but attenuates those in a specific range to very low levels
Detectors : [Information]
In radio, a detector is a device or circuit that extracts information from a modulated radio frequency current or voltage
The modulated AM carrier wave is received by the antenna of the radio receiver and is rectified by the action of a detector diode
Impedance Matching : [Information]
Impedance matching is the practice of designing the input impedance of an electrical load or the output impedance of its corresponding signal source to maximize the power transfer or minimize signal reflection from the load.
It is very important to transfer radio frequency energy from a generator to a load through transmission lines with zero or minimum power loss
Impedance mismatch in the transmission line will cause some of the signal power reaching to the load to be reflected back and produce standing wave.
Most power amplifiers have a low output impedance, typically less than 50 Ω. 2. The RF source is a transistor amplifier with an output impedance of 10 Ω that is to be matched to 50-Ω output impedance load. The L-network with a parallel output capacitor is used
Functional layout of a seperate transmitter and receiver requires:
A T/R (transmit/receive) switch to change between transmitter and receiver, the switch can be either RF sensing or manual switch.
Signal to Noise Ratio (S/N Ratio) [Information]
Defined by stating the minimum signal voltage at input to produce an output with a certain ratio of signal above noise level in a specified bandwidth at a particular frequency.
Signal to Noise Ratio (SNR) is a figure of merit that compares the level of a desired signal to the level of background noise. It is calculated as the ratio of signal power to the noise power. SNR is expressed in dB (decibles).
Typical 0.5μV for 10dB S/N in 3 kHz for SSB at 28 MHz
Two resistors connected in series R1 (2 ohms) and R2 (4 ohms) are connected in parallel with 2 resistors also connected in series R3 (6 ohms) and R4 (6 ohms) with a supply voltage of 12 Volts. What is the total resistance ?
2 ohms
4 ohms
8 ohms
12 ohms
What is the total amps ?
1 amps
2 amps
3 amps
4 amps
What is the amps going through R1 and R2
1 amp
2 amps
3 amps
4 amps
What is the amps going through R3 and R4
1 amp
2 amps
3 amps
4 amps
What is the voltage drop across R1 and R2 ?
R1 6 volts : R2 6 volts
R1 2 volts : R2 8 volts
R1 4 volts : R2 8 volts
R1 8 volts : R2 2 volts
What is the voltage drop across R3 and R4 ?
R3 4 volts : R4 8 volts
R3 6 volts : R4 4 volts
R3 5 volts : R4 7 volts
R3 6 volts : R4 6 volts
What is the total power ?
18 watts
24 watts
30 watts
36 watts
Filters : T Filter : L Filter : Pi Filter : Consant K Filter : [Information]
T Filter : The high-pass T filter has a very low impedance at high frequencies, and a very high impedance at low frequencies. That means that it can be inserted in a transmission line, resulting in the high frequencies being passed and low frequencies being reflected.
L Filter : The low-pass versions are probably the most widely used since they attenuate harmonics, noise, and other undesired signals. The L network is very simple and works well for matching values of impedance that aren’t too different.
Pi Filter : Pi networks can also be used to match the output impedance of one circuit to the input impedance of another or the output impedance of a transmitter to the input impedance of an antenna.
Constant K Filters, also k-type filters, are a type of electronic filter designed using the image method.
Oscillator : [Information]
An oscillator is an electronic circuit where some of the amplified output is fed back (positive feedback) to the input to maintain a flywheel effect or oscillations. For extreme accuracy a Quartz crystal is sometimes used to maintain frequency.
An electronic oscillator is an electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave.
Q :What are three oscillator circuits used in amateur radio equipment? A : Colpitts, Hartley and Pierce
Oscillator circuits are commonly used in VFOs are ? A : Colpitts and Hartley
Logic Gates : AND : NAND : OR : NOR : [Information]
Logic gates process signals which represent true or false. Normally the positive supply voltage +Vs represents true and 0V represents false. Other terms used for the true and false are 1 and 0 : High and Low. The symbols 0 (false) and 1 (true) are usually used in truth tables
AND gate, the output is true (1) when both inputs are true (1) OR gate, the output is true (1) if either or both of the inputs are true (1)
NAND gate the output is false (0) if both inputs are true (1) NOR gate the output is true (1) if both inputs are false (1)
Radio Receiver [Information]
The purpose of a radio receiver is to acquire a radio (RF) signal containing information in the form of modulation and to process it into an audible (AF) sound.A receiver should have: Sensitivity – to resolve weak signals satisfactorily without introducing noise Selectivity – to separate the required signal from unwanted or interfering ones
Amplify weak signal from antenna (RF Amplifier) Select required signal (VFO Tuner) Filter out unwanted signals Detector (Demodulator) recovers modulation from the signal. Amplify audio output (AF Amplifier)
Automatic Gain Control (AGC) : Automatically controls receiver gain to maintain constant output level, prevents overload of amplifier stages
S meter : Indicates the strength of the received signal usually as measured at the output of the I.F. stage or detector (audio-derived).Calibrated in S-points (0 – 9) and 10 dB points above S9
Beat Frequency Oscillator (BFO) [Information]
In a radio receiver, a beat frequency oscillator or BFO is a dedicated oscillator used to create an audio frequency signal from Morse code radiotelegraphy (CW) transmissions to make them audible.
The signal from the BFO is mixed with the received signal to create a heterodyne or beat frequency which is heard as a tone in the speaker/headphones.
To receive Morse code signals, a BFO is employed in a superhet receiver to beat with the IF signal to produce an audio tone
Radio Transmitter (Basic) [Information]
Audio Stage : The very low signal from the microphone (mic) is amplified to the required level and then passed onto the next stage (Modulator).......The microphone converts sound waves into electrical signals (a range of 20 Hz to 20 kHz).
Modulator Stage : Mixes the signal from the audio stage with the Frequency generator to give the signal that the last stage (Power Amplifier) amplifies.
Frequency Generation Stage (Oscillator) : This generates the frequency to be transmitted and is mixed in the modulator with the audio stage in readiness for the (Power Amplifier) amplifier stage.
Power Amplifier Stage : This amplifies the small signal from the modulator and send it via the feeder (usually coax but not always) to the antenna.
Voltage Regulator [Information]
A voltage regulator is used to regulate voltage level. When a steady, reliable voltage is needed, then voltage regulator is the preferred device. It generates a fixed output voltage that remains constant for any changes in an input voltage or load conditions. It acts as a buffer for protecting components from damage.
Tuned Radio Frequency (TRF) Receiver. [Information]
The tuned radio frequency receiver is one in which the tuning or selectivity is provided at the radio frequency stages. Typically a TRF receiver would consist of three main sections:RF amplifier : Dectector : Audio Amplifier:
RF Amplifier and Tuning : This consisted of one of more amplifying and tuning stages.
The detector recovers the AM signal, the recovered audio is passed to the Audio Amplifier stage Audio Amplifier:
The Audio Amplifier stage makes the recovered audio signal louder so that it is sufficient to hear in a loudspeaker.
Amplifiers [Information]
A circuit designed to increase the level of its input signal is called: An amplifier
The increase in signal level by an amplifier is called: Gain
A device with gain has the property of: Amplification
The following is not amplified by an amplifier. Resistance
Variable Frequency Oscillator (VFO) [Information]
VFO in electronics is an oscillator whose frequency can be tuned (i.e., varied) over some range.
Altering the frequency of the VFO will control the frequency to which the radio is tuned.
The Colpitts and Hartley oscillator circuits are commonly used in a VFO.
In order for an oscillator circuit to work in must have sufficient positive feedback.
Element 8 includes :Circuit design selection of circuit component values.....Some information can be found in NTC Amateur Radio Exam Information.pdf and So You Want To Be A Ham [Information]
Voltage regulator with pass transistor and zener diode produce given output voltage
Select coil and capacitor to reasonate given frequency
LC preselector with fixed and variable capacitors to tune a given frequency range
Single - stage amplifier to have desired frequency response by proper selection of bypass and coupling capacitors.
Element 8 includes the topics listed below....Some information can be found in NTC Amateur Radio Exam Information.pdf and So You Want To Be A Ham [Information]
Block diagrams including for receiver and transmitter.
Circuit design selection of circuit component values
Calculations of voltages, currents power in common amateur radio circuits