RF Circuits Flashcards
What is the effective radiated power of a repeater with 75 watts transmitter output power, 4 dB feedline loss, 3 dB duplexer/circulator loss, and 10 dB antenna gain (3-67J2)?
150 Watts
What component in a radio receives varying DC voltage from the detector and filters it to a steady DC voltage and then amplifies the voltage to use as a control for the RF amplifier?
AGC
What part of the electromagnetic spectrum includes wavelengths ranging from 700 nm to 400 nm?
Visible Light
What test equipment is used to test coaxial cables for shorts and opens and determine the location of those faults?
Time Domain Reflectometer
What is the surge impedance of aircraft coaxial cable?
50 Ohms
The _________ band includes frequencies between 300 kHz and 3 MHz.
Medium Frequency (MF)
What radio component is a device that releases RF signal in the form of an electromagnetic field?
Antenna
What happens to bandwidth if the modulating frequency is increased?
Bandwidth Increases
The __________ band includes frequencies ranging from 300 MHz to 3 GHz.
Ultra High Frequency (UHF)
Which antenna is considered to be a vertically polarized antenna?
Marconi
A radio wave is composed of an E-field and an H-field. Which of these is the magnetic field?
H-Field
What type of carrier wave does DME and transponders use?
On/Off Keyed
Using RC time constants, what happens to frequency when a long time constant is used?
Frequency Decreases
What type of hollow conductor works best for high energy applications?
Waveguide
In a super regenerative receiver, where can the bandpass filters be found?
At the RF section
What is the effective radiated power of a repeater with 100 watts transmitter output power, 5 dB feedline loss, 4 dB duplexer/ circulator loss, and 10 dB antenna gain (3-67J5)?
126 Watts
What radio component extracts the audio frequencies from the modulated RF signal?
Detector
What is sometimes installed in waveguides to prevent moisture from condensing?
Nitrogen
In a blocking oscillator the blocking condition is determined by the______?
Capacitor discharge
In modern avionics, what component/circuit can accomplish the same effect on an oscillator as a variable capacitor or variable inductor?
Frequency synthesizer
The __________ band includes frequencies ranging from 30 MHz to 300 MHz.
Very High Frequency (VHF)
What type of modulation is used for aircraft communications?
AM
The level at which the smallest or minimum discernible signal can pass to a receiver’s RF section is called what?
Noise Floor
Upper VHF band and above waves propagate as:
Space waves
What type of oscillator should be used to create square, sawtooth, rectangular, triangular, or any combination of these wave forms?
Non-sinusoidal oscillator
The largest tolerable signal a receiver’s detector/discriminator can safely process defines a receiver’s what?
Signal ceiling
When using a 555 timer as a multivibrator, the output frequency is controlled by varying what? (2)
Resistors and capacitors
In what type of receiver does an IF section filter out all frequencies except the difference between the RF and LO frequencies?
Super-Heterodyne/Dual Super-Heterodyne
How fast do ground waves travel?
At the speed of light
The difference between the upper and lower sidebands is known as:
The bandwidth
Which type of wave propagation is best suited for long distance communications beyond the visual horizon without “gaps” or dead spots?
Ground waves
__________________ is the duration of the pulse that the modulating signal varies.
Pulse width
What radio transmitter component isolates the transmitter from the master oscillator?
Buffer
What type(s) of wave form(s) is/are created with an astable multivibrator? (2)
Square and Rectangular
________________ is the strength or magnitude of a waveform.
Amplitude
What frequency range is typically associated with audio frequencies (AF)?
20Hz - 20kHz
The main benefits of using the GaAsFET transistor in avionics equipment is:
High gain, Low noise
Transmitter 1 has 12 watts of output power. Transmitter 2 has 14 watts of output power. How many dB greater is transmitter 2’s power level?
+0.669 dB
HF and lower band VHF waves travel as:
Sky waves
The __________ band includes frequencies ranging from 30 GHz to 300 GHz.
Extremely High Frequency (EHF)
In a super heterodyne receiver, which section filters out all the frequencies except the difference between the RF and LO frequencies?
IF section
What is the effective radiated power of a repeater with 75 watts of transmitter power output, 5 dB feedline loss, 4 dB duplexer/circulator loss, and 6 dB antenna gain (3-67J3)?
37.6 Watts
What is the metal braiding in coaxial cable known as?
Shielding
What type of transmission line consists of a center conductor surrounded with a dielectric?
Coaxial Cable
What type of theoretical radiator transmits well in all directions in a spheroid pattern?
Isotropic radiator
A power change of a factor of 10 is equal to decibel level change of:
10 dB
What term describes the tendency for Radio Frequency (RF) AC current to be greater on the surface of a conductor or transmission line than near the center?
Skin-effect
A radio receiver is expected to operate normally between its Minimum Discernible and Largest Tolerable signals. This is called the receiver’s ______________________.
Dynamic range
What test equipment is used to test and determine a transmission line’s forward and reflected power? (Two answers)
In-line wattmeter & VSWR meter
What is the effective radiated power of a repeater with 50 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer/circulator loss, and 7 dB antenna gain (3-67J6)?
31.5 Watts
In a free-running multivibrator, what determines the frequency?
The coupling circuit
The sum of the modulating frequency and the carrier frequency is known as:
Upper sideband
What component in a FM receiver performs the same function as the detector found in an AM receiver?
Discriminator
The relationship between the E-field and H-field is that they travel:
At right angles to each other
Using RC time constant, what happens to frequency when a short time constant is used?
Frequency increases
Which antenna consists of two 1/4 wavelength wires placed end to end?
Hertzian
What part of the electromagnetic spectrum includes wavelengths ranging from 1 mm to 700 nm?
Infrared Radiation
What radio component is a relaxation oscillator that can function in either of two temporarily stable conditions and is capable of rapidly shifting from one temporary state to another?
Multivibrators
In order to get the best reception possible, antennas should:
Have the same polarization
The __________ band includes frequencies ranging from 3 GHz to 30 GHz.
Super High Frequency (SHF)
The _________ band includes frequencies between 3 MHz and 30 MHz.
High Frequency (HF)
What radio component is used to decrease the gain of the RF amplifier?
AGC
________________ is the distance between any point on a wave and the equivalent point on the next wave.
Wavelength
Which frequency bands does a Yagi-Uda antenna typically operate in? (Three answers)
HF, VHF, & UHF
In FM, what is used to control the frequency of the oscillator?
An audio wave
A change in power by a factor of two is approximately equivalent to a decibel change of:
3 dB
What is the effective radiated power of a repeater with 100 watts transmitter power output, 4 dB feedline loss, 3 dB duplexer/circulator loss, and 7 dB antenna gain (3-67J4)?
100 Watts
What band on the electromagnetic spectrum does the audio frequency (AF) range fall in?
Very low frequency (VLF)
The _________ band includes frequencies between 30 kHz and 300 kHz.
Low frequency (LF)
Which portion of a wave carries the information?
The carrier signal
What frequencies are present in the mixer stage of a receiver?
RF, LO, Sum, Difference
What is another name for a “Blocking” Oscillator?
Quench oscillator
What is the result when a received signal is in-phase and adds to the reference signal in a Receiver/Transmitter using Phase Shift Keying (PSK) modulation?
A digital “one”
The difference between the modulated frequency and the carrier frequency is known as:
Lower sideband
What radio component reduces strong signals which might overload the detector?
AGC
What radio transmitter component provides the basic carrier wave?
Stabilized master oscillator
What is the effective radiated power (ERP) of a repeater with 50 watts transmitter output power, 4 dB feedline loss, 3 dB duplexer/circulator loss, and 6 dB antenna gain (3-67J1)?
39.7 Watts
What type of cable is most commonly used as aircraft transmission lines?
Coaxial Cable
