Chapter 5: Amateur Radio Equipment Flashcards
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.
Name a control that could be used if the voice pitch of a single-sideband signal seems too high or low.
Receiver incremental tuning, allows you to tune in a station that is slightly off frequency or to adjust the pitch of an operator’s voice that seems too high or too low.
What does the term “RIT” mean?
Receiver Incremental Tuning
What is the advantage of having multiple receive bandwidth choices on a multi-mode transceiver?
Having multiple filters available allows you to reduce noice or interference by selecting a filter with just enough bandwidth to pass the desired signal.
What is an appropriate receive filter bandwidth for minimizing noise and interference for SSB reception?
Wide filters (around 2.4kHz) are used for SSB reception.
What is an appropriate receive filter bandwidth for minimizing noise and interference for CW reception?
Narrow filters (around 500 Hz) are used for CW and data mode reception.
What could be used to remove power line noise or ignition noise?
A noise blanker
What is the function of the SSB/CW-FM switch on a VHF power amplifier?
The SSB/CW switch on the front panel is used to control the set mode of the power amplifier.
What device increases the low-power output from a handheld transceiver?
An RF power amplifier
What device converts the RF input and output of a transceiver to another band?
Transverters allow one main transceiver to be used on one or more new bands.
How might a computer be used as part of an amateur radio station?
Bookkeeping chores such as logging contacts, operating on the digital modes, and sending/receiving CW.
What code is used when sending CW in the amateur bands?
Morse code
Name a popular VHF/UHF digital communications mode?
Packet radio based on AX.25 protocol
B2F protocol for Winlink system messaging
JT65 for moon bounce and MSK144 for scatter paths
IEEE 802.11 (WiFi) adapted to amateur use on microwave bands
Name a popular HF digital communications mode?
Radioteletype (RTTY) using the 5-bit Baudot code
Keyboard to keyboard modes such as PSK31
Weak-signal modes such as FT8 and WSPR
PACTOR or WINMOR modes for Winlink system messaging
What components may be included in packet transmissions?
Header and data: information about the packet and call sign of destination; a checksum that allows the receiver to detect errors; automatic repeat requests (ARQ)
What is an ARQ transmission system?
Automatic repeat request; if an error is detected, the receiver automatically requests that the packet be retransmitted until the data is received properly.
What does the abbreviation “PSK” mean?
Phase Shift Keying, most popular keyboard-to-keyboard mode (PSK31 with the 31 symbolizing 31 baud rate)
What does the term “APRS” mean?
Automatic Packet Reporting System, uses packet radio to transmit the position information from a moving or portable station.
What device is used to provide data to the transmitter when sending automatic position reports from a mobile amateur radio station?
A GPS Receiver
What is a common application of APRS?
To provide maps of station locations while they are providing real-time tactical communications
Which computer sound card port is connected to a transceiver’s headphone or speaker output for operating digital modes?
Connected to one of the computer’s digital data ports via a COM port or USB interface.
Which connection might be used between a voice transceiver and a computer for digital operation?
Transceiver connected to computers digital data ports, then connected to radio’s microphone input and speaker/headphone output.
How is a computer’s sound card used when conducting digital communications?
If sound card is used, output is connected to radio’s microphone input and speaker is connected to sound card input.
What name is given to an amateur radio station that is used to connect other amateur stations to the Internet?
The gateway.
Which of the following best describes Broadband-Hamnet, also referred to as a high-speed multi-media network?
The modification of firmware of some commercial Wi-Fi routers so they automatically connect to each other forming data networks. Proven useful in public service and emergency communications.
What operating activities are supported by digital mode software in the WSJT suite?
JT65 for moonbounce (or Earth-Moon-Earth, EME); weak-signal propagation beacons (WSPR), and meteor scatter (MSK144).
What is FT8?
Open source software capable of operating in low signal-to-noise conditions by transmitting special code sequences on 15-second intervals
What must be considered to determine the minimum current capacity needed for a transceiver power supply?
You must consider the transmitter’s efficiency at full power output, how much current the receiver and control circuits require, and the power supply’s regulation and ability to dissipate heat at full load.
How much voltage does a mobile transceiver typically require?
12V
What type of circuit controls the amount of voltage from a power supply?
A regulator circuit is used to minimize the amount of voltage change.
What is the source of a high-pitched whine that varies with engine speed in a mobile transceiver’s receive audio?
Alternator whine is caused by noise on the DC power system inside your own vehicle.
Where should the negative return connection of a mobile transceiver’s power cable be connected?
Connect the negative lead to the negative battery terminal or where the battery ground lead is connected to the vehicle’s body.
What can happen is a lead-acid storage battery is charged or discharged too quickly?
Storage batteries can release or vent flammable hydrogen gas, that can cause an explosion.
List the types of batteries that are rechargeable.
Nickel-Cadmium, Nickel-Metal Hydride, Lithium Ion, Lead-acid
List the types of batteries that are NOT rechargeable.
Alkaline, Carbon-Zinc, Lithium
