Part of our Getting On The Air: Modes, Operations, and Making Contacts guide.
The G90 is a great little radio for digital modes once it’s set up correctly, but it has a couple of quirks worth knowing about going in. Unlike radios with a single USB port that does everything, the G90 splits CAT and audio across two different connections, and getting that straight up front saves a lot of troubleshooting later.
What you’ll need
- Xiegu G90
- A Digirig Mobile with the Xiegu G90-specific cable set (Digirig sells a factory cable made for this radio, it’s worth buying the correct one rather than improvising)
- WSJT-X installed
Understanding the G90’s two connections
The G90 has an IO-port that Xiegu’s own blue USB cable plugs into for CAT control and firmware updates, but that cable does not carry audio. The actual audio in/out and PTT for digital modes goes through the ACC port, a mini-DIN-8 socket on the back of the radio. The Digirig’s G90 cable set is built to handle both of these at once, so from the Digirig side it’s a single USB-C connection to your computer, but it still physically connects to two different points on the radio.
Connecting to the computer
- Connect the Digirig’s CAT cable to the G90’s IO-port and the audio/PTT cable to the ACC port.
- Connect the Digirig to your computer with USB-C.
- In Device Manager, you should see a virtual COM port appear for CAT, along with a USB audio device for the Digirig’s sound card.
- If you run into trouble getting CAT to connect, plug in Xiegu’s native blue USB cable first and confirm CAT works with that alone. This isolates whether an issue is your software configuration or the Digirig connection itself, once confirmed working, swap back to the Digirig and just update the COM port number in your software.
Radio menu settings
- Mode: USB or USB-D, this is Xiegu’s recommended mode for FT8
- Turn off: Pre-Amp, Noise Blanker, Compression, and AGC, all of these processing features interfere with clean digital decoding
- Data input: the G90 should be set so the ACC port’s LINE IN is used as the audio input in data mode (this mutes the hand mic and enables LINE OUT via the ACC socket automatically when the radio is in data mode)
- AUX IN Volume: adjust this in the system menu to set the input level coming from the computer, start at a mid-level setting and fine-tune from there
- Power output: set to roughly 50% of full output, around 10W. FT8 has long key-down times per transmission, and running the G90 at full 20W continuously for digital modes risks overheating and distortion
- USB-Serial port (CAT): 19200 bps, 8 data bits, no parity, 1 stop bit
Setting up WSJT-X
- General tab: callsign and grid square.
- Radio tab: newer WSJT-X versions include a Xiegu G90 profile directly in the Rig dropdown, select it if it’s there. If it isn’t available in your version, use FLRig as a go-between instead: FLRig has a dedicated Xiegu G90 configuration, so you’d point WSJT-X’s Rig setting to “FLRig” and let FLRig handle the actual CAT connection to the radio. Either way, set Serial Port to the Digirig’s CAT COM port, Baud Rate to 19200, Data Bits 8, Stop Bits 1, Handshake None. Set PTT Method to CAT.
- Audio tab: select the Digirig’s USB audio device for both input and output.
- Test CAT and Test PTT before going further. If the COM port field appears grayed out while already set to CAT, switch PTT Method to something else temporarily, change the port, then switch back to CAT, this is a known quirk in some configurations.
Getting on the air with FT8
- Sync your computer’s clock, FT8 depends on accurate timing down to about a second
- Tune to a standard FT8 frequency in USB, 14.074 MHz on 20m or 7.074 MHz on 40m are consistently active
- Watch your ALC, target a value between roughly 30 and 85. Raise the computer’s audio output level until the ALC just starts responding, then stop there rather than pushing further
- Keep power around 10W as set above, FT8 doesn’t reward running higher power and the G90 will run cooler and cleaner at this level
Making your first contact
Once decoded stations start showing up in the left-hand panel, double-click any station calling CQ. WSJT-X handles the rest of the exchange automatically over the following 15-second cycles, sending your callsign, grid, and signal reports as needed. Once you see “73” logged in the right-hand panel, that’s a completed contact.
If nothing’s decoding, double-check the clock sync first, that’s the most common culprit. After that, confirm you’re actually seeing audio activity on WSJT-X’s signal level indicator, and make sure Pre-Amp, Noise Blanker, Compression, and AGC are all genuinely off on the radio, since any one of them left on can be enough to keep the decoder from locking onto anything useful.
For more on the interface used here, see What Is a Digirig? If you’re running the G90 portable, Building a Xiegu G90 Manpack covers the rest of that setup.