Connection
Connect rear REMOTE (CI-V) to the PC using a compatible CI-V interface. Connect external sound hardware/radio interface to ACC(1) (8-pin). A USB CI-V cable alone carries no audio. TX: PC output → MOD; RX: AF → PC input.
Radio settings · AFSK
Select LSB and turn DATA ON. Check the DATA indicator. External PTT mutes the microphone, but microphone PTT enables it; disconnect the microphone. No USB audio input setting.
| Item | Setting / check |
|---|---|
| Mode | Select LSB and turn DATA ON. Check the DATA indicator. External PTT mutes the microphone, but microphone PTT enables it; disconnect the microphone. No USB audio input setting. |
| ACC(1) (8-pin) pin 4 MOD | Interface TX audio → ACC(1) (8-pin) pin 4 MOD. |
| ACC(1) (8-pin) pin 5 AF | ACC(1) (8-pin) pin 5 AF → interface RX input. Normally independent of the AF knob. S2 fixed side: 100–300 mV rms independent of AF knob. SP side follows AF; check RX volume effects on modified settings. |
| ACC(1) (8-pin) pin 2 GND | Connect pin 2 GND as specified by the audio interface. |
| ACC(1) pin 3 SEND | Compatible PTT interface grounds pin 3 SEND to transmit. A CI-V cable alone cannot operate this PTT line. |
| CI-V Address | Default IC-275: 10h / IC-375: 12h. Match PSRTTY to the radio’s actual CI-V address. |
| CI-V Baud Rate | Match CI-V Baud Rate and PC speed. |
| Audio TX level | Start with low PC/interface/PSRTTY TX volume. There is no USB MOD Level setting on the radio. |
| MAIN S1 → MOD input level | Keep working FT8 settings. S1: 100 mV side = 10 kΩ/100 mV rms; 3 mV side = 600 Ω/3 mV rms. Input conditions differ greatly. Independent of MIC GAIN: adjust external interface and PSRTTY output. |
| MAIN S2 → AF output | S2 fixed side: 100–300 mV rms independent of AF knob. SP side follows AF; check RX volume effects on modified settings. |
FSK keying transmission · Ver1.18
Example: DTR for FSK and CI-V/CAT for PTT. Adjust settings to your wiring and selected signals.
IC-275
The manufacturer manual specifies AFSK operation for this model. Native direct FSK keying is not supported; use normal AFSK mode.
Manufacturer reference: manual / USB port settings (IC-275)
IC-375
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 through the same ACC audio, keep wiring/gain and change USB to LSB. Check DATA ON and retain external PTT.
PSRTTY settings · AFSK
Select IC-275 / IC-375, CI-V COM and explicit external Audio IN/OUT. Automatic mode switching on connection OFF; set the radio mode described above. Select external PTT and match interface COM, RTS/DTR and polarity. Close apps using the same COM.
No modulation
Compare FT8/PSRTTY output devices → check radio mode → TX audio to MOD and RX audio from AF → interface levels. If CAT works but no modulation, check audio cable and Audio OUT first. Keep working FT8 settings. S1: 100 mV side = 10 kΩ/100 mV rms; 3 mV side = 600 Ω/3 mV rms. Input conditions differ greatly. Independent of MIC GAIN: adjust external interface and PSRTTY output.
Official sources
Based on official manuals for each model. Check pin numbers in the rear-view diagram. For generation or regional differences, follow the manual for your radio.