Sub Element G4: Amateur Radio Practices Flashcards
What is the purpose of the “notch filter” found on many HF transceivers?
To reduce interference from carriers in the receiver passband.
What is one advantage of selecting the opposite, or “reverse,” sideband when receiving CW signals on a typical HF transceiver?
It may be possible to reduce or eliminate interference from other signals
What is normally meant by operating a transceiver in “split” mode?
The transceiver is set to different transmit and receive frequencies
What reading on the plate current meter of a vacuum tube RF power amplifier indicates correct adjustment of the plate tuning control?
A pronounced dip
What is a reason to use Automatic Level Control (ALC) with an RF power amplifier?
To reduce distortion due to excessive drive
What type of device is often used to match transmitter output impedance to an impedance not equal to 50 ohms?
Antenna coupler or antenna tuner
What condition can lead to permanent damage to a solid-state RF power amplifier?
Excessive drive power
What is the correct adjustment for the load or coupling control of a vacuum tube RF power amplifier?
Maximum power output without exceeding maximum allowable plate current
Why is a time delay sometimes included in a transmitter keying circuit?
To allow time for transmit-receive changeover operations to complete properly before RF output is allowed
What is the purpose of an electronic keyer?
Automatic generation of strings of dots and dashes for CW operation
Which of the following is a use for the IF shift control on a receiver?
To avoid interference from stations very close to the receive frequency
Which of the following is a common use for the dual-VFO feature on a transceiver?
To permit monitoring of two different frequencies
What is one reason to use the attenuator function that is present on many HF transceivers?
To reduce signal overload due to strong incoming signals
What is likely to happen if a transceiver’s ALC system is not set properly when transmitting AFSK signals with the radio using single sideband mode?
Improper action of ALC distorts the signal and can cause spurious emissions
Which of the following can be a symptom of transmitted RF being picked up by an audio cable carrying AFSK data signals between a computer and a transceiver?
The VOX circuit does not un-key the transmitter
The transmitter signal is distorted
Frequent connection timeouts
All these choices are correct
How does a noise blanker work?
By reducing receiver gain during a noise pulse
What happens as the noise reduction control level in a receiver is increased?
Received signals may become distorted
What item of test equipment contains horizontal and vertical channel amplifiers?
An oscilloscope
Which of the following is an advantage of an oscilloscope versus a digital voltmeter?
Complex waveforms can be measured
Which of the following is the best instrument to use when checking the keying waveform of a CW transmitter?
An oscilloscope
What signal source is connected to the vertical input of an oscilloscope when checking the RF envelope pattern of a transmitted signal?
The attenuated RF output of the transmitter
Why is high input impedance desirable for a voltmeter?
It decreases the loading on circuits being measured
What is an advantage of a digital voltmeter as compared to an analog voltmeter?
Better precision for most uses
What signals are used to conduct a two-tone test?
Two non-harmonically related audio signals
Which of the following instruments may be used to monitor relative RF output when making antenna and transmitter adjustments?
A field strength meter
Which of the following can be determined with a field strength meter?
The radiation pattern of an antenna
Which of the following can be determined with a directional wattmeter?
Standing wave ratio
Which of the following must be connected to an antenna analyzer when it is being used for SWR measurements?
Antenna and feed line
What problem can occur when making measurements on an antenna system with an antenna analyzer?
Strong signals from nearby transmitters can affect the accuracy of measurements
What is a use for an antenna analyzer other than measuring the SWR of an antenna system?
Determining the impedance of coaxial cable
What is an instance in which the use of an instrument with analog readout may be preferred over an instrument with a digital readout?
When adjusting tuned circuits
What type of transmitter performance does a two-tone test analyze?
Linearity
Which of the following might be useful in reducing RF interference to audio frequency devices?
Bypass capacitor
Which of the following could be a cause of interference covering a wide range of frequencies?
Arcing at a poor electrical connection
What sound is heard from an audio device or telephone if there is interference from a nearby single sideband phone transmitter?
Distorted speech
What is the effect on an audio device when there is interference from a nearby CW transmitter?
On-and-off humming or clicking
What might be the problem if you receive an RF burn when touching your equipment while transmitting on an HF band, assuming the equipment is connected to a ground rod?
The ground wire has high impedance on that frequency
What effect can be caused by a resonant ground connection?
High RF voltages on the enclosures of station equipment
Why should soldered joints not be used with the wires that connect the base of a tower to a system of ground rods?
A soldered joint will likely be destroyed by the heat of a lightning strike
Which of the following would reduce RF interference caused by common-mode current on an audio cable?
Placing a ferrite choke around the cable
How can a ground loop be avoided?
Connect all ground conductors to a single point
What could be a symptom of a ground loop somewhere in your station?
You receive reports of “hum” on your station’s transmitted signal
What technique helps to minimize RF “hot spots” in an amateur station?
Bonding all equipment enclosures together
Which of the following is an advantage of a receiver DSP IF filter as compared to an analog filter?
A wide range of filter bandwidths and shapes can be created
Why must the metal enclosure of every item of station equipment be grounded?
It ensures that hazardous voltages cannot appear on the chassis
What is the purpose of a speech processor as used in a modern transceiver?
Increase the intelligibility of transmitted phone signals during poor conditions
Which of the following describes how a speech processor affects a transmitted single sideband phone signal?
It increases average power
Which of the following can be the result of an incorrectly adjusted speech processor?
Distorted speech
Splatter
Excessive background pickup
All these choices are correct
What does an S meter measure?
Received signal strength
How does a signal that reads 20 dB over S9 compare to one that reads S9 on a receiver, assuming a properly calibrated S meter?
It is 100 times more powerful
Where is an S meter found?
In a receiver
How much must the power output of a transmitter be raised to change the S meter reading on a distant receiver from S8 to S9?
Approximately 4 times
What frequency range is occupied by a 3 kHz LSB signal when the displayed carrier frequency is set to 7.178 MHz?
7.175 to 7.178 MHz
What frequency range is occupied by a 3 kHz USB signal with the displayed carrier frequency set to 14.347 MHz?
14.347 to 14.350 MHz
How close to the lower edge of the phone segment should your displayed carrier frequency be when using 3 kHz wide LSB?
At least 3 kHz above the edge of the segment
How close to the upper edge of the phone segment should your displayed carrier frequency be when using 3 kHz wide USB?
At least 3 kHz below the edge of the band
What is the purpose of a capacitance hat on a mobile antenna?
To electrically lengthen a physically short antenna
What is the purpose of a corona ball on an HF mobile antenna?
To reduce RF voltage discharge from the tip of the antenna while transmitting
Which of the following direct, fused power connections would be the best for a 100 watt HF mobile installation?
To the battery using heavy-gauge wire
Why is it best NOT to draw the DC power for a 100 watt HF transceiver from a vehicle’s auxiliary power socket?
The socket’s wiring may be inadequate for the current drawn by the transceiver
Which of the following most limits an HF mobile installation?
Efficiency of the electrically short antenna
What is one disadvantage of using a shortened mobile antenna as opposed to a full- size antenna?
Operating bandwidth may be very limited
Which of the following may cause receive interference in a radio installed in a vehicle?
The battery charging system
The fuel delivery system
The vehicle control computer
All these choices are correct
What is the name of the process by which sunlight is changed directly into electricity?
Photovoltaic conversion
What is the approximate open-circuit voltage from a fully illuminated silicon photovoltaic cell?
0.5 VDC
What is the reason that a series diode is connected between a solar panel and a storage battery that is being charged by the panel?
The diode prevents self-discharge of the battery though the panel during times of low or no illumination
