T4B02: Frequency entry: Of the following can be used to enter a

Q: Which of the following can be used to enter a transceiver’s operating frequency?

The correct answer is A: The keypad or VFO knob. The correct answer is A: The keypad or VFO knob. You can enter a transceiver's operating frequency using the keypad (to directly enter the frequency) or the VFO knob (Variable Frequency Oscillator knob, to tune up and down). These are the primary methods for frequency entry on modern transceivers. Most modern transceivers have both methods: a keypad for direct frequency entry (you type in 146.520 for example) and a VFO knob for tuning (you rotate the knob to change frequency). Some transceivers also have memory channels you can recall, but the keypad and VFO knob are the fundamental methods for setting frequency. CTCSS/DTMF encoders and AFC are for other functions, not frequency entry.

Updated: Dec 9, 2025 | Source: 2022-2026 Question Pool | Topic: T4B

T4B02T4B

Which of the following can be used to enter a transceiver’s operating frequency?

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Deep Dive: T4B02

The correct answer is A: The keypad or VFO knob. You can enter a transceiver's operating frequency using the keypad (to directly enter the frequency) or the VFO knob (Variable Frequency Oscillator knob, to tune up and down). These are the primary methods for frequency entry on modern transceivers. Most modern transceivers have both methods: a keypad for direct frequency entry (you type in 146.520 for example) and a VFO knob for tuning (you rotate the knob to change frequency). Some transceivers also have memory channels you can recall, but the keypad and VFO knob are the fundamental methods for setting frequency. CTCSS/DTMF encoders and AFC are for other functions, not frequency entry.

Why Other Answers Are Wrong

Option B: Incorrect. CTCSS and DTMF encoders are for tone signaling and repeater control, not for entering operating frequency. Option C: Incorrect. Automatic Frequency Control (AFC) automatically adjusts receive frequency to track signals, but it doesn't let you enter a frequency - it follows signals automatically. Option D: Incorrect. Not all options are correct. Only the keypad and VFO knob are used for frequency entry.

Exam Tip

Enter frequency = Keypad or VFO knob. Remember: You enter a transceiver's operating frequency using the keypad (direct entry) or VFO knob (tuning). These are the standard methods.

Memory Aid

**E**nter **F**requency = **K**eypad or **V**FO (think 'EF = KV' = Keypad or VFO)

Real-World Example

You want to tune to 146.52 MHz. You can either use the keypad to directly enter '146.52' and press enter, or you can use the VFO knob to tune up or down from your current frequency until you reach 146.52 MHz. Both methods work - the keypad is faster for known frequencies, the VFO knob is convenient for scanning or fine-tuning.

Source & Coverage

Question Pool: 2022-2026 Question Pool

Subelement: T4B

Reference: FCC Part 97.3

Key Concepts

Frequency entry Keypad VFO knob Transceiver controls

Verified Content

Question from the official FCC Technician Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the T4B topic.