Connection
IC-271 is a CI-IV-generation radio. CAT requires an installed UX-14 or compatible converter, then a compatible PC interface connected to its CI-V port. A CI-V USB cable alone cannot perform conversion. This guide uses model-specific interface audio into front MIC; RX audio from 24-pin ACC pin 4, GND pin 8. Wiring differs from ordinary 8-pin ACC(1).
Radio settings · AFSK
Select plain LSB on the radio. TX uses MIC input: adjust MIC GAIN and external audio volume. Use the model-specific cable without a microphone in parallel. No LSB-D or USB audio input switching.
| Item | Setting / check |
|---|---|
| Mode | Select plain LSB on the radio. TX uses MIC input: adjust MIC GAIN and external audio volume. Use the model-specific cable without a microphone in parallel. No LSB-D or USB audio input switching. |
| MIC input (model-specific interface cable) | Connect an IC-271-compatible interface/cable to front MIC at microphone-level audio. Follow its audio-ground wiring. Ordinary 8-pin ACC pin 4 MOD instructions do not apply to this radio. |
| ACC (24-pin) pin 4 AF | 24-pin ACC pin 4 is fixed RX detector output, independent of AF knob. Connect to compatible interface Audio IN. |
| ACC (24-pin) pin 8 GND | 24-pin ACC pin 8 is GND. Follow the model-specific cable for MIC audio ground. Match connector type and pin numbers. |
| ACC (24-pin) pin 3 PTT | 24-pin ACC pin 3 is external PTT input. A compatible circuit grounds pin 3 to pin 8 for TX. Separate from CI-V frequency control. |
| CI-V Address (converter) | Default 20h. Match PSRTTY to the radio’s actual CI-V address. |
| Baud (installed converter) | Match PSRTTY baud to the installed UX-14/compatible converter. Replacement units may have separate PC-side and CI-V-side speeds; follow their manual. |
| Audio TX level / MIC GAIN | Adjust MIC GAIN, interface and PSRTTY TX volume from low levels. MIC GAIN = 0 prevents modulation with this MIC-input route. |
FSK keying transmission · Ver1.18
Example: DTR for FSK and CI-V/CAT for PTT. Adjust settings to your wiring and selected signals.
The manufacturer manual specifies AFSK operation for this model. Native direct FSK keying is not supported; use normal AFSK mode.
If FT8 already works
If FT8 works in plain USB through the same external audio device, keep wiring/gain first, switch the radio to LSB and test RTTY. Do not switch to LSB-D.
PSRTTY settings · AFSK
In PSRTTY 1.16 select external PTT and match the compatible interface COM, RTS/DTR and polarity. CI-V CAT, audio and PTT are separate paths. Automatic mode switching on connection OFF; select plain LSB on the radio. Choose explicit external Audio IN/OUT and the exact radio model.
No modulation
No frequency: check converter installation, connection, address and baud. No modulation: front MIC audio/MIC GAIN. No RX: ACC pins 4/8 and Audio IN. No TX: external PTT pins 3/8.
Official sources
- IC-271A/E manufacturer instruction manual, p.8 / 28 (archived copy)
- Icom UX-14 manufacturer instruction manual (archived copy)
- Compatible UX-14PX converter: manufacturer operational notes — PIEXX
Uses an archived manufacturer-issued IC-271A/E manual and CI-IV/CI-V converter documentation. Check domestic variants and installed converter differences against your own manuals.