Technicians Exam-Station Setup

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rledwith
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221482
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Technicians Exam-Station Setup
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2013-06-13 12:26:14
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rdl tech exam t4
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Amateur Radio Technicians Exam - T4 Question Set - Station Setup
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  1. T4A01 Which of the following is true concerning the microphone connectors on amateur transceivers?
    A. All transceivers use the same microphone connector type
    B. Some connectors include push-to-talk and voltages for powering the microphone
    C. All transceivers using the same connector type are wired identically
    D. Un-keyed connectors allow any microphone to be connected
    • B. Some connectors include push-to-talk and voltages for powering the microphone
    • The microphone connector of a transceiver is likely to include push-to-talk connections and also supply voltage for powering electret-style microphones. The wiring of the connector varies for the different manufacturers, so check the connections before trying a new microphone. [Ham Radio License Manual, page 5-5]
  2. T4A02 What could be used in place of a regular speaker to help you copy signals in a noisy area?
    A. A video display
    B. A low pass filter
    C. A set of headphones
    D. A boom microphone
    • C. A set of headphones
    • Using headphones blocks wind noise and noise from nearby people or machinery. Remember that the same noise may be picked up by your microphone, so take steps to shield it from noise as well. [Ham Radio License Manual, page 2-13]
  3. T4A03 Which is a good reason to use a regulated power supply for communications equipment?
    A. It prevents voltage fluctuations from reaching sensitive circuits
    B. A regulated power supply has FCC approval
    C. A fuse or circuit breaker regulates the power
    D. Power consumption is independent of load
    • A. It prevents voltage fluctuations from reaching sensitive circuits
    • To operate properly, communications equipment requires a power supply with a stable output voltage. Regulation prevents voltage fluctuations of the input power source from causing similar fluctuations at the output. [Ham Radio License Manual, page 5-14]
  4. T4A04 Where must a filter be installed to reduce harmonic emissions?
    A. Between the transmitter and the antenna
    B. Between the receiver and the transmitter
    C. At the station power supply
    D. At the microphone
    • A. Between the transmitter and the antenna
    • Due to minor imperfections, every transmitter’s RF output signal contains weak harmonics of the desired output signal and other spurious emissions that can cause interference to nearby equipment. In extreme cases, a misadjusted or defective transmitter can generate strong interfering signals. To prevent harmonics from being radiated, a low-pass or band-pass filter must be installed at the transmitter’s connection to the antenna feed line. [Ham Radio License Manual, page 5-20]
  5. T4A05 What type of filter should be connected to a TV receiver as the first step in trying to prevent RF overload from a nearby 2 meter transmitter?
    A. Low-pass filter
    B. High-pass filter
    C. Band-pass filter
    D. Band-reject filter
    • D. Band-reject filter
    • If the interfering signal’s frequency is close to the desired signal’s frequency, it may not be possible to prevent overload with a high-pass or low-pass filter because the desired signal will be attenuated, as well. For example, when a TV receiver is overloaded by a nearby 2 meter transmitter, a notch or band-reject filter is required. The notch filter attenuates the 2 meter signal without also filtering out over-the-air broadcast channels 2 - 13. [Ham Radio License Manual, page 5-20]
  6. T4A06 Which of the following would be connected between a transceiver and computer in a packet radio station?
    A. Transmatch
    B. Mixer
    C. Terminal node controller
    D. Antenna
    • C. Terminal node controller
    • The terminal node controller (TNC) converts the audio signals from your radio’s receiver output to data characters for the computer. Similarly, characters from the computer are converted to audio signals that your transmitter can use. The TNC may also act as the push-to-talk switch to turn the transmitter on and off. [Ham Radio License Manual, page 5-11]
  7. T4A07 How is the computer’s sound card used when conducting digital communications using a computer?
    A. The sound card communicates between the computer CPU and the video display
    B. The sound card records the audio frequency for video display
    C. The sound card provides audio to the microphone input and converts received audio to digital form
    D. All of these choices are correct
    • C. The sound card provides audio to the microphone input and converts received audio to digital form
    • Sound cards and their host computers have become sufficiently powerful that for several popular digital modes such as RTTY and PSK31, there is no need for a separate TNC or protocol controller. The sound card and software running on the host can perform the necessary conversions between audio signals and data characters. [Ham Radio License Manual, page 5-11]
  8. T4A08 Which type of conductor is best to use for RF grounding?
    A. Round stranded wire
    B. Round copper-clad steel wire
    C. Twisted-pair cable
    D. Flat strap
    • D. Flat strap
    • Connections to an RF ground bus should be made with a short, wide conductor such as copper flashing or strap or heavy solid wire (#8 AWG or larger). Solid strap is best because it presents the lowest impedance to RF current. [Ham Radio License Manual, page 5-24]
  9. T4A09 Which would you use to reduce RF current flowing on the shield of an audio cable?
    A. Band-pass filter
    B. Low-pass filter
    C. Preamplifier
    D. Ferrite choke
    • D. Ferrite choke
    • RF choke or common-mode filters made of ferrite material are used to reduce RF currents flowing on unshielded wires such as speaker cables, ac power cords and telephone modular cords. Ferrite chokes are also used to reduce RF current flowing on the outside of shielded audio and computer cables. [Ham Radio License Manual, page 5-18]
  10. T4A10 What is the source of a high-pitched whine that varies with engine speed in a mobile transceiver’s receive audio?
    A. The ignition system
    B. The alternator
    C. The electric fuel pump
    D. Anti-lock braking system controllers
    • B. The alternator
    • Alternator whine is a type of noise caused by noise on the dc power system inside your own vehicle. You might hear it with the received audio but more likely it will be heard by others as a high-pitched whine on your transmitted signal that varies with your engine speed. It can be removed by a dc power filter at your radio. [Ham Radio License Manual, page 5-15]
  11. T4A11 Where should a mobile transceiver’s power negative connection be made?
    A. At the battery or engine block ground strap
    B. At the antenna mount
    C. To any metal part of the vehicle
    D. Through the transceiver’s mounting bracket
    • A. At the battery or engine block ground strap
    • Connect the radio’s negative lead to the negative battery terminal or where the battery ground lead is connected to the vehicle body. Do not rely on ground connections via the vehicle’s body because vehicle sections may not be bonded together dependably. Many body components may be plastic or composite, as well. The most reliable negative power connection is directly to the battery or its ground strap. [Ham Radio License Manual, page 5-14]
  12. T4B01 What may happen if a transmitter is operated with the microphone gain set too high?
    A. The output power might be too high
    B. The signal might become distorted
    C. The frequency might vary
    D. The SWR might increase
    • B. The signal might become distorted
    • Your transmitter will produce spurious emissions if your microphone gain is too high. For example, on an SSB transmitter the resulting overmodulation creates spurious signals on nearby frequencies. On FM, the result will be excessive deviation that can cause your signal to encroach on an adjacent channel. [Ham Radio License Manual, page 5-4]
  13. T4B02 Which of the following can be used to enter the operating frequency on a modern transceiver?
    A. The keypad or VFO knob
    B. The CTCSS or DTMF encoder
    C. The Automatic Frequency Control
    D. All of these choices are correct
    • A. The keypad or VFO knob
    • The VFO (variable frequency oscillator) is the circuit that controls the frequency of operation on both receive and transmit. Many radios also have a numeric keypad that allows you to enter the desired frequency directly. The VFO is used when you are tuning across the band looking for a station or particular signal. Keypads are used when changing directly between known frequencies. [Ham Radio License Manual, page 5-2]
  14. T4B03 What is the purpose of the squelch control on a transceiver?
    A. To set the highest level of volume desired
    B. To set the transmitter power level
    C. To adjust the automatic gain control
    D. To quiet the noise when no signal is being received
    • D. To quiet the noise when no signal is being received
    • In the absence of a signal on an FM receiver, you will hear noise. FM receivers have a squelch circuit that cuts off the speaker unless a signal is present, called “closing” the squelch. The squelch control adjusts the threshold at which squelch circuits turn the speaker on and off. The proper setting for the squelch control is just above the point at which the receiver audio is cut off. If set at a higher level, some signals will not be strong enough to “open” the squelch. [Ham Radio License Manual, page 5-6]
  15. T4B04 What is a way to enable quick access to a favorite frequency on your transceiver?
    A. Enable the CTCSS tones
    B. Store the frequency in a memory channel
    C. Disable the CTCSS tones
    D. Use the scan mode to select the desired frequency
    • B. Store the frequency in a memory channel
    • By storing the frequency and any other pertinent information in a memory channel you can quickly return to the frequency at any time. [Ham Radio License Manual, page 5-2]
  16. T4B05 Which of the following would reduce ignition interference to a receiver?
    A. Change frequency slightly
    B. Decrease the squelch setting
    C. Turn on the noise blanker
    D. Use the RIT control
    • C. Turn on the noise blanker
    • Ignition noise consists of a sharp pulse each time a spark plug in the engine fires. Just like the early spark radio transmitters, the arc produces RF signals across a wide range of frequencies. You hear the signals as buzzing or raspy noise that changes pitch along with engine speed. The noise blanker circuit in your radio detects these pulses and mutes the receiver for a short period. [Ham Radio License Manual, page 5-7]
  17. T4B06 Which of the following controls could be used if the voice pitch of a single-sideband signal seems too high or low?
    A. The AGC or limiter
    B. The bandwidth selection
    C. The tone squelch
    D. The receiver RIT or clarifier
    • D. The receiver RIT or clarifier
    • Receiver incremental tuning (RIT) is a fine-tuning control used for SSB or CW operation. RIT allows the operator to adjust the receiver frequency without changing the transmitter frequency. This 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 low. [Ham Radio License Manual, page 5-6]
  18. T4B07 What does the term “RIT” mean?
    A. Receiver Input Tone
    B. Receiver Incremental Tuning
    C. Rectifier Inverter Test
    D. Remote Input Transmitter
    • B. Receiver Incremental Tuning
    • Receiver incremental tuning (RIT) is a fine-tuning control used for SSB or CW operation. RIT allows the operator to adjust the receiver frequency without changing the transmitter frequency. This 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 low. [Ham Radio License Manual, page 5-6]
  19. T4B08 What is the advantage of having multiple receive bandwidth choices on a multimode transceiver?
    A. Permits monitoring several modes at once
    B. Permits noise or interference reduction by selecting a bandwidth matching the mode
    C. Increases the number of frequencies that can be stored in memory
    D. Increases the amount of offset between receive and transmit frequencies
    • B. Permits noise or interference reduction by selecting a bandwidth matching the mode
    • IF filters are specified by bandwidth in Hz or kHz. Wide filters (around 2.4 kHz) are used for SSB reception on phone. Narrow filters (around 500 Hz) are used for Morse code and data mode reception. Having multiple filters available allows you to reduce noise or interference by selecting a filter with just enough bandwidth to pass the desired signal. [Ham Radio License Manual, page 5-6]
  20. T4B09 Which of the following is an appropriate receive filter to select in order to minimize noise and interference for SSB reception?
    A. 500 Hz
    B. 1000 Hz
    C. 2400 Hz
    D. 5000 Hz
    • C. 2400 Hz
    • IF filters are specified by bandwidth in Hz or kHz. Wide filters (around 2.4 kHz) are used for SSB reception on phone. Narrow filters (around 500 Hz) are used for Morse code and data mode reception. Having multiple filters available allows you to reduce noise or interference by selecting a filter with just enough bandwidth to pass the desired signal. [Ham Radio License Manual, page 5-6]
  21. T4B10 Which of the following is an appropriate receive filter to select in order to minimize noise and interference for CW reception?
    A. 500 Hz
    B. 1000 Hz
    C. 2400 Hz
    D. 5000 Hz
    • A. 500 Hz
    • IF filters are specified by bandwidth in Hz or kHz. Wide filters (around 2.4 kHz) are used for SSB reception on phone. Narrow filters (around 500 Hz) are used for Morse code and data mode reception. Having multiple filters available allows you to reduce noise or interference by selecting a filter with just enough bandwidth to pass the desired signal. [Ham Radio License Manual, page 5-6]
  22. T4B11 Which of the following describes the common meaning of the term “repeater offset”?
    A. The distance between the repeater’s transmit and receive antennas
    B. The time delay before the repeater timer resets
    C. The difference between the repeater’s transmit and receive frequencies
    D. The maximum frequency deviation permitted on the repeater’s input signal
    • C. The difference between the repeater’s transmit and receive frequencies
    • To send a signal through a repeater, you must transmit on the repeater’s input frequency where the repeater receiver listens, called the repeater’s input frequency. You then listen where the repeater transmits, called the repeater’s output frequency. To make it easy to use many different repeaters, hams have decided on a standard separation between input and output frequencies. The difference between repeater input and output frequencies is called the repeater’s offset or shift. (See question T2A01) [Ham Radio License Manual, page 6-16] *T2A01 - The amount of repeater offset or shift is the same for almost all repeaters on one band as shown in the table below. This standardization makes it easy to use many different repeaters. Note that offset can often be either positive or negative by region or to allow more repeaters to occupy a single band, so be sure to use a repeater directory to determine the proper offset. [Ham Radio License Manual, page 6-16]

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