Technician T4B: Operating controls
These are the 11 official questions in group T4B of the 2026–2030 Technician question pool, with the correct answer marked and a plain-English explanation of why it's right. The real exam asks one question from this group.
- T4B01Question 1
What is the effect of excessive microphone gain on SSB transmissions?
- AFrequency instability
- BDistorted transmitted audio Correct
- CIncreased SWR
- DSideband inversion
Why: Too much mic gain overdrives the transmitter and distorts your audio.
- T4B02Question 2
Which of the following can be used to enter a transceiver’s operating frequency?
- AThe keypad or VFO knob Correct
- BThe CTCSS or DTMF encoder
- CThe Automatic Frequency Control
- DAll these choices are correct
Why: Most transceivers let you enter a frequency on the keypad or with the VFO knob.
- T4B03Question 3
How is squelch adjusted so that a weak FM signal can be heard?
- ASet the squelch threshold so that receiver output audio is on all the time Correct
- BTurn up the audio level until it overcomes the squelch threshold
- CTurn on the anti-squelch function
- DEnable squelch enhancement
Why: Opening the squelch all the way keeps the audio on, so even a very weak signal can be heard.
- T4B04Question 4
What does an FM signal sound like when received slightly off frequency?
- AThe audio increases in pitch
- BThe audio decrease in pitch
- CThere is no effect except for reduction in amplitude
- DThe audio becomes distorted Correct
Why: An FM signal received slightly off frequency sounds distorted.
- T4B05Question 5
What does the scanning function of an FM transceiver do?
- AChecks incoming signal deviation
- BPrevents interference to nearby repeaters
- CTunes through a range of frequencies to check for activity Correct
- DTunes through a range of frequencies to determine the antenna’s resonant frequency
Why: Scan tunes through a range of frequencies or memories, looking for activity.
- T4B06Question 6
Which of the following controls could be used if the voice pitch of a single-sideband signal returning to your CQ call seems too high or low?
- AThe AGC or limiter
- BThe bandwidth selection
- CThe tone squelch
- DThe RIT or Clarifier Correct
Why: RIT (Clarifier) shifts only your receive frequency to fix the other station's pitch.
- T4B07Question 7
What is a DMR “code plug”?
- AAn adapter cable used to connect a DMR radio to a computer for internet access
- BConfiguration data loaded onto your radio to access repeaters and talkgroups Correct
- CAn upgrade to DMR programming software provided by the radio manufacturer to accommodate new radio models
- DA Coder-Decoder (CODEC) that converts analog voice data to DMR digital data and vice versa
Why: A DMR code plug is the configuration file that sets up repeaters and talkgroups in your radio.
- T4B08Question 8
What is the advantage of having a choice of receiver filter bandwidths in a multimode transceiver?
- APermits monitoring several modes simultaneously by selecting a separate filter for each mode
- BPermits noise or interference reduction by selecting a bandwidth matching the mode Correct
- CIncreases the number of frequencies that can be stored in memory
- DIncreases the amount of offset between receive and transmit frequencies
Why: Choosing a filter width that matches the mode cuts noise and nearby interference.
- T4B09Question 9
How is a specific group of stations selected on a DMR digital voice transceiver?
- ABy retrieving the frequencies from transceiver memory
- BBy enabling the group’s CTCSS tone
- CBy entering the group’s identification code Correct
- DBy inserting a five-pin, pre-programmed code plug
Why: On DMR you select a group by entering its talkgroup ID.
- T4B10Question 10
Which of the following receiver filter bandwidths provides the best signal-to-noise ratio for SSB reception?
- A500 Hz
- B1000 Hz
- C2400 Hz Correct
- D5000 Hz
Why: A 2,400 Hz filter matches an SSB voice signal's width, which gives the best signal-to-noise ratio.
- T4B11Question 11
Which of the following must be programmed into a D-STAR digital transceiver before transmitting?
- AYour call sign Correct
- BYour output power
- CThe codec type being used
- DAll these choices are correct
Why: D-STAR radios send your call sign digitally, so you have to program it in first.