General · correct answers only, in question-pool order.
A notch filter sharply reduces a narrow frequency inside the receiver passband, making it useful for suppressing an interfering carrier.
Changing to the opposite CW sideband moves received signals to the other side of the passband and can place an interfering signal outside the filter response.
A noise blanker responds to short noise pulses by temporarily reducing receiver gain during the pulse.
When a vacuum-tube RF amplifier is properly tuned, the plate current shows a pronounced dip.
Automatic level control keeps the exciter from driving an RF power amplifier too hard.
An antenna tuner presents a better impedance match to the transmitter, increasing the transfer of transmitter power into the feed line.
Aggressive noise reduction processing can alter the wanted audio along with the noise, making received signals sound distorted.
The LOAD or COUPLING control is adjusted for the desired RF output while keeping plate current within its allowable limit.
An external amplifier needs a short interval to switch its antenna path before RF arrives from the transceiver.
An electronic keyer automatically generates properly timed dots and dashes for CW operation.
AFSK data should be transmitted without active ALC because ALC action can distort the signal.
Dual VFOs make split operation easy by allowing the radio to transmit on one frequency while listening on another.
A receive attenuator reduces a very strong incoming signal before it reaches sensitive receiver stages, helping prevent overload.
An oscilloscope has horizontal and vertical channel amplifiers that control the time-axis and signal display.
Unlike a digital voltmeter, an oscilloscope shows how voltage changes with time, so it can display complex waveforms.
A CW transmitter's keying waveform is a time-domain signal, so an oscilloscope is the best instrument for examining its rise, fall, and shape.
To view the transmitted RF envelope, feed an attenuated sample of the transmitter's RF output to the oscilloscope's vertical input.
A voltmeter with high input impedance draws very little current from the circuit, so it disturbs the circuit less while measuring it.
Digital multimeters generally provide higher precision than typical analog multimeters.
A two-tone test uses two audio tones that are not harmonically related, producing a useful test signal for checking amplifier behavior.
A two-tone test is used to examine the linearity of an SSB transmitter or amplifier.
An analog meter's moving pointer makes trends and peaks easy to see while adjusting a circuit for a maximum or minimum.
A directional wattmeter measures forward and reflected power, which allows standing wave ratio to be determined.
For an SWR measurement with an antenna analyzer, connect the antenna and its feed line directly to the analyzer.
Strong nearby RF can enter an antenna analyzer and interfere with its internal measurements, producing inaccurate SWR readings.
An antenna analyzer can measure impedance properties of coaxial cable.
A bypass capacitor provides a low-impedance path for unwanted RF while leaving the wanted audio-frequency signal comparatively unaffected.
Arcing at a poor electrical connection generates broadband electrical noise that can spread across a wide range of frequencies.
When SSB RF is unintentionally detected by an audio device, the result is usually distorted speech rather than clean intelligible audio.
CW RF interference in an audio device follows the transmitter's on-off keying, producing humming or clicking in the same pattern.
A ground wire can have high RF impedance even if it is a good DC conductor. That impedance can allow large RF voltages to develop and cause burns.
A resonant ground connection can develop high RF voltage, placing dangerous RF potential on station equipment enclosures.
Lightning current can produce enough heat to destroy a soldered joint, so lightning-protection grounding should use mechanically robust connections.
A ferrite choke adds impedance to common-mode RF current flowing on an audio cable and can reduce the resulting interference.
Bonding equipment enclosures together keeps them at nearly the same RF and AC ground potential and helps reduce ground-loop effects.
A ground loop in station audio wiring can introduce mains-frequency hum into the transmitted audio.
Bonding all equipment enclosures together helps keep RF potential differences from developing between pieces of station equipment.
Grounding metal equipment enclosures helps ensure that a fault does not leave dangerous voltage on the chassis.
A speech processor increases the apparent loudness of transmitted voice by raising the average level of speech energy.
On SSB, speech processing increases average transmitted power rather than the transmitter's allowed peak power.
The official G4D03 source lists distorted speech as one effect of an incorrectly adjusted speech processor.
The official G4D03 source identifies excess intermodulation products as another result of incorrect speech-processor adjustment.
The official G4D03 source lists excessive background noise as an effect of incorrect speech-processor adjustment.
An S meter indicates the strength of the signal being received.
A 20 dB increase in power corresponds to a factor of 100, so a signal reading 20 dB over S9 is 100 times as powerful as an S9 signal.
One S unit is conventionally treated as a 6 dB change in signal strength.
Moving from S8 to S9 is one S unit, or about 6 dB. A 6 dB power increase is approximately four times the power.
An LSB signal extends below the displayed carrier frequency. A 3 kHz LSB signal displayed at 7.178 MHz therefore occupies about 7.175 to 7.178 MHz.
A USB signal extends above the displayed carrier frequency. A 3 kHz USB signal displayed at 14.347 MHz occupies about 14.347 to 14.350 MHz.
Because LSB extends below the displayed carrier frequency, a 3 kHz-wide LSB signal should be displayed at least 3 kHz above the lower band edge.
Because USB extends above the displayed carrier frequency, a 3 kHz-wide USB signal should be displayed at least 3 kHz below the upper band edge.
A capacitance hat adds capacitive loading near the end of a short antenna, making the antenna electrically longer than its physical length.
A corona ball reduces electric-field concentration at the antenna tip, lowering the chance of RF voltage discharge or corona while transmitting.
A 100-watt HF mobile transceiver draws substantial current, so the preferred supply is a direct fused battery connection using heavy-gauge wire.
A vehicle auxiliary power socket and its wiring may not be rated for the current required by a 100-watt HF transceiver.
HF mobile antennas are electrically short on the lower bands, and their low efficiency is often the major performance limitation.
A shortened antenna usually has higher Q than a full-size antenna, which can make its usable operating bandwidth quite narrow.
The official G4E07 source identifies the vehicle battery charging system as a possible source of HF receive interference.
The official G4E07 source lists the vehicle fuel delivery system as a possible source of receive interference.
The official G4E07 source identifies vehicle control computers as a possible source of HF receive interference.
Solar-panel cells are connected in combinations of series and parallel so the panel can provide useful voltage and current.
A fully illuminated silicon photovoltaic cell produces about 0.5 volts with no load connected.
A series diode blocks reverse current so the storage battery does not discharge back through the solar panel when illumination is low or absent.
A lithium iron phosphate battery must be charged through an appropriate charge controller when connected to a solar panel.