T4 — Amateur Radio Practices
2 exam questions · 2 groups · 24 questions in pool
The hands-on side of running a station: wiring up power, audio, and computer connections, and then driving the radio’s controls — squelch, filters, memories, RIT, and the settings that digital modes need. No FCC citations here.
T4A — Station Setup; Bonding; Mobile Installation
12 questions
What this group tests: connecting power supplies, SWR/power meters, computers for digital modes, and proper bonding/grounding, especially in mobile installs.
Foundational concepts
Power. A 50 W mobile FM rig needs roughly 13.8 volts at 12 amperes — VHF/UHF amateur gear runs on nominal 12 V (really ~13.8 V) and pulls substantial current on transmit. Use short, heavy-gauge DC wires to minimize voltage drop when keying up, and connect the radio’s negative return to the battery/chassis ground. To estimate battery runtime, divide the battery’s amp-hour rating by the average current draw.
Metering. An RF power meter (and SWR meter) goes in the feed line between the transmitter and the antenna, since that’s where forward and reflected power can be sampled. When choosing an SWR meter, match it to the frequency and power level you’ll measure.
Digital/computer connections. For sound-card digital modes you interconnect three things: received audio, transmit audio, and transmitter keying (PTT). Practically, the transceiver’s audio output feeds the computer’s input and vice-versa — e.g., transceiver speaker out → computer “line in.” FT8 specifically runs through WSJT-X software on a connected computer. A hot spot lets a handheld reach digital voice/data systems over the internet, and a code plug / talkgroup workflow lives in that digital world too.
Bonding (tying metal parts together so they’re at the same RF potential) is best done with flat copper strap, which has low impedance at RF — round wire has too much inductance. Lastly, an electronic keyer is a device that assists manual Morse sending.
Key facts to retain
- 50 W mobile FM → 13.8 V @ ~12 A; short heavy DC leads; negative return to chassis ground.
- Battery runtime = amp-hours ÷ average current.
- SWR/power meter goes in the feed line, TX-to-antenna.
- Digital interface carries RX audio, TX audio, keying; FT8 uses WSJT-X.
- Bond at RF with flat copper strap; hot spot links to internet digital systems.
External reference anchors
- NCVEC syllabus: T4A — Station setup; bonding; Mobile radio installation
Per-question map
| Q | Asks for | Resolved by |
|---|---|---|
| T4A01 | Supply for 50 W mobile FM | 13.8 V at 12 A |
| T4A02 | Choosing an SWR meter | Match frequency and power level |
| T4A03 | Why short heavy DC wires | Minimize voltage drop on transmit |
| T4A04 | FT8 audio connection | To a computer running WSJT-X |
| T4A05 | Where to install RF power meter | In the feed line, TX to antenna |
| T4A06 | Signals in a digital interface | RX audio, TX audio, keying |
| T4A07 | Computer↔transceiver digital link | Computer line-in to transceiver speaker |
| T4A08 | Preferred RF bonding conductor | Flat copper strap |
| T4A09 | Battery runtime calculation | Amp-hours ÷ average current |
| T4A10 | Function of a digital hot spot | Digital voice/data via internet |
| T4A11 | Mobile negative power return | At the 12 V battery chassis ground |
| T4A12 | What an electronic keyer is | Assists manual Morse sending |
T4B — Operating Controls
12 questions
What this group tests: the front-panel controls — tuning, squelch, scanning, memories, filters/bandwidth, RIT, mic gain — and the parameters digital voice radios need.
Foundational concepts
Frequency is entered by keypad or VFO knob. Memory channels store a favorite frequency for instant recall, and the scan function tunes through a range checking for activity.
Squelch mutes the receiver until a signal appears; to hear a weak FM signal you set the squelch threshold so the audio stays on all the time (just barely open). Tuning an FM receiver off the signal’s frequency (above or below) produces distorted audio — FM has to be tuned right on.
Microphone gain set too high on SSB causes distorted transmitted audio (over- driving). On the receive side, bandwidth/filter choice matters: a narrower filter matched to the mode cuts noise and interference, and for SSB voice a bandwidth around 2400 Hz gives the best signal-to-noise (wide enough for speech, narrow enough to reject junk). If an incoming SSB voice sounds too high- or low-pitched, adjust the RIT (receiver incremental tuning), a.k.a. Clarifier, which shifts only your receive frequency.
Digital voice adds its own settings: select a group of stations by entering the group’s ID code; a DMR “code plug” holds repeater and talkgroup access info; and a D-STAR radio must have your call sign programmed before you transmit.
Key facts to retain
- Enter frequency via keypad or VFO; memory stores favorites; scan checks a range.
- Weak FM → open squelch (audio on all the time); mistuned FM → distortion.
- Excess SSB mic gain → distorted TX audio; best SSB receive bandwidth ≈ 2400 Hz.
- RIT/Clarifier fixes pitch on a received SSB signal.
- Digital voice: group by ID code; DMR code plug = repeater/talkgroup info; D-STAR needs your call sign.
External reference anchors
- NCVEC syllabus: T4B — Operating controls: tuning, filters, squelch, AGC, memory, noise blanker, mic gain, RIT, bandwidth, digital configuration
Per-question map
| Q | Asks for | Resolved by |
|---|---|---|
| T4B01 | Excess SSB mic gain effect | Distorted transmitted audio |
| T4B02 | Entering operating frequency | Keypad or VFO knob |
| T4B03 | Squelch for weak FM | Audio on all the time |
| T4B04 | Quick access to a favorite | Store in a memory channel |
| T4B05 | What scanning does | Tunes a range checking for activity |
| T4B06 | Fixing SSB pitch on RX | RIT / Clarifier |
| T4B07 | DMR code plug contents | Repeater & talkgroup access info |
| T4B08 | Benefit of bandwidth choices | Match bandwidth to mode, cut noise |
| T4B09 | Selecting a digital station group | Enter the group’s ID code |
| T4B10 | Best SSB filter bandwidth | 2400 Hz |
| T4B11 | D-STAR pre-transmit setting | Your call sign |
| T4B12 | Mistuned FM receiver | Distorted audio |