Connection
Connect rear USB Type-B to the PC with a data cable. USB carries CI-V and TX/RX audio; no separate audio interface is needed. Install the official driver and select USB (A), the CI-V COM among the two virtual ports.
Radio settings · AFSK
Open MENU → SET → Connectors. TX: MOD Input; RX: USB AF/IF Output. USB input means audio via the connector, not USB sideband.
| Item | Setting / check |
|---|---|
| Mode | Start with LSB-D: SSB Data, not the radio’s native RTTY mode. |
| MOD Input → DATA MOD | Set USB: shared by LSB-D/USB-D. Factory default is ACC; check whether the FT8 preset or earlier setup already selected USB. |
| MOD Input → USB MOD Level | Keep the working FT8 value first. Factory default: 50%. Adjust with PSRTTY TX volume. |
| USB AF/IF Output → Output Select | AF: sends received audio to the PC. |
| USB AF/IF Output → AF SQL | OFF (OPEN): prevents radio squelch from cutting PC audio. |
| USB AF/IF Output → AF Output Level | Keep the working FT8 value and check PSRTTY RX level. |
| CI-V → CI-V Address | Default A2h. Match PSRTTY to the radio’s actual CI-V address. |
| USB (B)/DATA Function → USB (B) Function | Use USB (A) for CAT. USB (B) Function = RTTY Decode/DV Data serves other purposes; PSRTTY audio decoding does not need it. |
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) | USB (A) DTR / USB (B) DTR |
| USB Keying (CW) | OFF |
| USB SEND | OFF |
| Operating mode | RTTY / RTTY-R |
| RTTY shift | 170 Hz |
| RTTY Mark frequency | 2125 Hz |
For radios with A/B ports
| Shared CI-V port | USB Keying (RTTY) |
|---|---|
| A | USB (A) DTR |
| B | USB (B) DTR |
A/B identifies a port; DTR/RTS identifies its line. When sharing CI-V, select the same A/B side for USB Keying (RTTY). CI-V on B depends on the model/port-function setting. The original IC-7300 has no A/B choice: select DTR/RTS only.
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-9700)
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-9700 and CI-V CAT PTT. Explicitly select its USB CI-V COM and the same IC-9700 USB audio device for Audio IN/OUT. Start with LSB-D. Close other apps using that COM.
No modulation
Compare FT8 and PSRTTY output devices → verify LSB-D after connection → check DATA MOD = USB → check USB MOD Level and PC/PSRTTY transmit volume. Start with low audio and observe radio power and ALC.
Official sources
Based on official IC-9700 documentation. Menu names/positions may vary with firmware or language.