Yaesu FT-991A setup — and the VHF “no audio” trap
The FT-991A’s built-in USB sound card makes it a one-cable digital-modes rig — but it routes transmit audio differently on every mode, and settings that work on HF silently do nothing on 2 m / 70 cm. If the rig keys up but transmits a dead carrier — in Open Signal, MMSSTV, or any other program — it is almost always this.
HF — SSB digital (DATA-USB)
- Set the mode to DATA-USB — not plain USB.
- The rig takes transmit audio from the USB codec in this mode — which is why HF “just works”.
Levels
- In Open Signal, the TX LEVEL slider is the master: 100% = full-scale audio into the codec. Start at about 50%.
- Watch the station log: after every transmission Open Signal reports
TX audio peak was N% of full scale, and on startup it reports the stream, the Windows device volume, and restores its own mixer volume if Windows muted or ducked it. - Set drive so SSB ALC barely moves (HF) or FM deviation sits near 3 kHz.
144 / 430 MHz (FM) — the trap
Plain FM mode takes TX audio from the microphone only. Your PC audio goes nowhere, PTT still keys, and you transmit an unmodulated carrier.
- Set the mode to DATA-FM (press MODE, choose DATA on an FM band).
- Menu 071 “FM PKT PORT SELECT” → USB — the default is DATA (the rear DIN socket), which is the trap: even DATA-FM stays silent until this points at the USB codec.
- Menu 070 “FM PKT PTT SELECT” — match your PTT method (RTS/DTR/DAKY).
- Menu 072 “FM PKT TX GAIN” — start mid-range, then adjust for about 3 kHz deviation while transmitting a test picture.
Menu numbers can shift slightly between firmware versions — go by the names.
This guidance comes from a live field-test session on 144 MHz. Other rigs with built-in codecs (IC-7300, IC-9700, FT-710…) have equivalent per-mode source settings under different menu names.
FT-991A digital modes — FAQ
Why does my FT-991A key up but transmit no audio on 2 m?
Plain FM mode takes transmit audio from the microphone only — your PC audio goes nowhere, PTT still keys, and you transmit an unmodulated carrier. Set the mode to DATA-FM and point menu 071 (FM PKT PORT SELECT) at USB. This affects every soundcard program, not just Open Signal.
Which FT-991A mode do I use for SSTV and digital pictures?
DATA-USB on HF (not plain USB), and DATA-FM on 144/430 MHz. In the DATA modes the rig takes its transmit audio from the built-in USB codec, which is why HF usually “just works” while FM silently does not.
What transmit level should I run?
Start the software TX level around 50% and adjust so SSB ALC barely moves on HF, or FM deviation sits near 3 kHz (menu 072, FM PKT TX GAIN). Open Signal reports “TX audio peak was N% of full scale” in the station log after every transmission, which makes this easy to dial in.
Do these settings apply to other rigs?
The principle does: rigs with built-in USB codecs (IC-7300, IC-9700, FT-710 and friends) all have an equivalent per-mode transmit-audio source setting under a different menu name. On the FT-991A itself, menu numbers can shift slightly between firmware versions — go by the menu names.
More about Open Signal
Rig sorted? Put a picture on the air
With DATA mode set and levels clean, sending a picture is three steps: pick a mode chip, choose a file, press Transmit.