Connection
Connect a data-capable USB cable from the rear USB Type-B port to the PC. USB carries CI-V and TX/RX audio; this connection needs no separate audio interface. Follow the official USB driver instructions.
Radio settings · AFSK
Open MENU → SET → Connectors. The basic approach matches IC-705, but RX audio items are named ACC/USB. USB input here means audio via the USB connector, not USB sideband.
| Item | Setting / check |
|---|---|
| Mode | Start with LSB-D: SSB Data, not the radio’s native RTTY mode. |
| DATA MOD | Set USB. Shared by LSB-D/USB-D; factory default is ACC, so check it. |
| USB MOD Level | Keep the working FT8 value first. Factory default: 50%. Adjust with PSRTTY TX volume. |
| ACC/USB Output Select | AF: sends received audio to the PC. |
| ACC/USB AF SQL | OFF (OPEN): prevents radio squelch from cutting PC audio. |
| ACC/USB AF Output Level | Keep the working FT8 value and check PSRTTY RX level. |
| USB Serial Function | CI-V: use the USB virtual COM for radio control. |
| USB SEND / USB Keying (RTTY) | CAT PTT in this guide does not use DTR/RTS SEND or FSK keying. Set OFF unless needed for another dedicated use. |
FSK keying transmission · Ver1.18
Example: DTR for FSK and CI-V/CAT for PTT. Adjust settings to your wiring and selected signals.
Serial keying for TX; Audio IN for RX. Neither primary nor secondary Audio OUT is used. Check radio RTTY mode, 170 Hz shift and Mark frequency. Keying polarity is independent of RX inversion.
Connect the radio to the PC with one USB cable to use FSK. See FSK keying output for the radio settings.
Radio settings
| Radio item / connection | Setting / matching |
|---|---|
| USB Keying (RTTY) | DTR |
| USB Keying (CW) | OFF |
| USB SEND | OFF |
| Operating mode | RTTY / RTTY-R |
| RTTY shift | 170 Hz |
| RTTY Mark frequency | 2125 Hz |
Keying polarity mapping
| PSRTTY inversion | DTR OFF | DTR ON |
|---|---|---|
| Not inverted | Mark | Space |
| Inverted | Space | Mark |
This table maps PSRTTY control signals. It is independent of A/B selection and RX decoding inversion. Start without inversion, then match the radio/interface polarity.
Manufacturer reference: manual / USB port settings (IC-7300)
If FT8 already works
With FT8 in USB-D, LSB-D uses the same DATA MOD and USB MOD Level. Check actual LSB-D after PSRTTY connects and keep input/gain first. Plain USB uses DATA OFF MOD; check DATA MOD separately for LSB-D.
PSRTTY settings · AFSK
Select IC-7300 and CI-V CAT PTT. Explicitly select its USB CI-V COM and the same IC-7300 USB audio device for Audio IN/OUT. Start with LSB-D. Close other apps using that COM.
No modulation
Compare FT8/PSRTTY output devices → check actual LSB-D → DATA MOD = USB → USB MOD Level and PC/PSRTTY TX volume. Start low while watching power and ALC. For CAT failures, check USB Serial Function = CI-V and matching CI-V address/baud rate.
Official sources
- IC-7300 / IC-7300M / IC-7300S — Icom
- IC-7300 / IC-7300M / IC-7300S 取扱説明書
- IC-7300 FULL MANUAL (English), 2-5 / 4-31 / 12-9–12-11
- IC-7300 Full Manual — Icom
Based on official IC-7300 documentation. Menu names/positions may vary with firmware or language.