Chapter 5: Amateur Radio Equipment Flashcards
(58 cards)
Name one form of amplitude modulation
Single-side band (SSB), where the carrier and one sideband is removed or suppressed.
What type of modulation is most commonly used for VHF packet radio transmission?
Frequency Modulation (FM)
Which type of modulation is most commonly used for VHF and UHF voice repeaters?
Frequency Modulation, due to its excellent noise-rejection qualities
Which type of voice mode is most often used for long-distance (weak signal) contacts on the VHF and UHF bands?
Single Sideband (SSB), because signal power is concentrated into a narrow bandwidth
Name a type of emission that has the narrowest bandwidth?
CW - 150 Hz
SSB digital - 500 to 3000 Hz
SSB voice - 2 to 3 kHz
What is an advantage of single sideband (SSB) over FM for voice transmissions?
SSB is concentrated into a narrow bandwidth, making it possible to communicate over longer ranges and in poorer conditions than FM or AM, particularly on VHF and UHF bands.
List the Bandwidth of the these different signals: CW SSB digital SSB Voice AM voice
CW - 150Hz
SSB Digital - 500-3000Hz
SSB Voice - 2 to 3kHz
AM Voice - 6kHz
Name the bandwidths of these various signals: AM broadcast: FM voice: FM broadcast: Commercial video broadcast:
AM Broadcast - 10kHz
FM Voice - 10-15kHz
FM Broadcast - 150kHz
Commercial Video Broadcast - 6MHz
What can be used to enter the operating frequency on a moder transceiver?
The radio’s keypad.
What is a way to enable quick access to a favorite frequency on your transceiver?
Radio Memories or “memory channels”
What is meant by PTT?
Push-to-Talk
What is the primary purpose of a dummy load?
To act as a heavy-duty resistor that can absorb and dissipate the output power from a transmitter.
What does a dummy load consist of?
A dummy load is a heavy-duty resistor that can absorb and dissipate the output power from a transmitter.
What is an electronic keyer?
A device that turns contact closures by a Morse paddle into a stream of dots and dashes.
Why should you not set your transmit frequency to be exactly at the edge of an amateur band or sub-band?
Amateurs must remember to leave room for the signals sidebands in order to keep all of signal inside the band.
What might be the problem if a repeater user says your transmissions are breaking up on voice peaks?
Overdeviation, in which the user is speaking too loudly into the microphone, causing interference on adjacent channels.
What may happen if a transmitter is operated with the microphone gain set too high?
Overmodulation, caused by speaking too loudly or setting the microphone gain too high, resulting in a distortion of the transmitted signal.
What can you do if you are told your FM handheld or mobile transceiver is over-deviating?
Speak more softly or move the microphone farther from your mouth.
What is the purpose of the squelch control?
The squelch circuit mutes the receiver’s audio output when no signal is present.
What is the function of automatic gain control, or AGC?
A receiver’s AGC circuitry constantly adjusts the receiver’s sensitivity to keep the output volume constant for both weak and strong signals.
Which term describes the ability of a receiver to detect the presence of a signal?
A receiver’s sensitivity determines its ability to detect signals.
Which term describes the ability of a receiver to discriminate between multiple signals?
Selectivity is the ability of a receiver to discriminate between signals.
Where is an RF preamplifier installed?
Connected between the antenna and receiver.
Name a component that would reduce ignition interference to a receiver?
A noise blanker (NB) sense the sharp pulses from arcing power lines, motors, or vehicle ignition systems and temporarily mutes the receiver during the pulse.
