Connection
Connect the main unit’s rear USB port 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 the CI-V USB1 COM. USB1/USB2 are two virtual COMs from one physical USB connector.
Radio settings · AFSK
Open SET → Connectors on the controller. USB MOD Level and DATA MOD are here; RX items are ACC/USB Output Select, USB Audio SQL and ACC/USB AF Level. USB input means connector audio, 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. USB MOD Level adjusts USB TX audio; DATA MOD Level is for the separate DATA jack, so do not confuse them. |
| 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. |
| USB Audio SQL | OFF (OPEN): prevents radio squelch from cutting PC audio. |
| ACC/USB AF Level | Keep the working FT8 value and check PSRTTY RX level. |
| CI-V → CI-V Address | Default 88h. Match PSRTTY to the radio’s actual CI-V address. |
| USB2/DATA1 Function → USB2 Function | Use the USB1 COM for CAT. USB2 Function = RTTY Decode outputs the radio’s decoded text; PSRTTY audio decoding and CAT do 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.
The manufacturer manual uses the ACC RTTY keying input for FSK. A separate serial port and a suitable FSK interface are required. A USB socket does not mean FSK is available with only a USB cable. Never connect RS-232 signals directly to ACC.
Radio settings
| Radio item / connection | Setting / matching |
|---|---|
| FSK input / keying | ACC (13-pin): RTTY / FSK |
| Serial connection | Use a separate FSK COM port from CAT for this model. Check the connection and avoid PTT signal conflicts. |
| Operating mode | RTTY / RTTY-R |
| RTTY shift | 170 Hz |
| RTTY Mark frequency | 2125 Hz |
| PTT (TX/RX switching) | Do not assign the same line to PTT and FSK |
| Audio IN | Use the usual receive audio input |
The manufacturer manual uses the ACC RTTY keying input for FSK. A separate serial port and a suitable FSK interface are required. A USB socket does not mean FSK is available with only a USB cable. Never connect RS-232 signals directly to ACC. With external control set to radio PTT, a dedicated FSK COM can share different lines, for example FSK=DTR and PTT=RTS. Keep this port separate from CAT and never assign both functions to one line.
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-7100)
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-7100 and CI-V CAT PTT. Explicitly select its USB CI-V COM and the same IC-7100 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-7100 documentation. Menu names/positions may vary with firmware or language.