Hardware & Software
edited for clarity: I left out the fact that I was using the Silicon Labs driver
- Radios: Yaesu FT-840, tr(uSDX), Baofeng UV-5R
- Digirig Mobile units:
- Unit #1 – purchased May 2024 (Amazon, fulfilled by Softcomplex LLC) Not used until late May 2025
- Unit #2 – purchased early June 2025 (Amazon, fulfilled by Softcomplex LLC)
- Unit #3 – purchased mid-June 2025 (Amazon exchange; currently on-hand)
- Cables:
- Yaesu GX16 Mic Cable for DigiRig
- Dedicated DigiRig cables for tr(uSDX) and UV-5R
- OS / software: Windows 10 Pro, WSJT-X 2.7.0
- Driver:
- Current - v11.4.0.393 Silicon Labs VCP USB Serial Bridge on Com9 sees the DigiRig and was utilized for all testing and troubleshooting of cables/DigiRig/radios. I started with the 6.7.6 version install that updated to current version noted above.
- Guido’s single-USB CAT/Audio driver (latest release as of May 2025) Does properly control the tr(uSDX) as a control test with the computer.
Symptoms
- Unit #1:
- Receives audio but will not trigger PTT via RTS on any radio.
- Unit #2:
- Passes bench test (RTS toggles open/short on 3.5 mm PTT jack)
- Once connected to FT-840 with GX16 cable, RTS line stays open; radio never keys.
- Same non-keying behavior on tr(uSDX) and UV-5R.
- Unit #3 (current):
- Bench test and UV-5R transmit PASS.
- Hesitant to connect to FT-840 until I understand why previous units failed.
Troubleshooting Performed
- Continuity checks on all cables (following DigiRig “Troubleshooting Digital Modes” video).
- All cables short sleeve → first ring (PTT) correctly and put each radio into transmit when unplugged from DigiRig.
- RTS loopback test with WSJT-X:
- Unit #1 & #2 – RTS line remains open (no continuity change).
- Unit #3 – RTS line toggles as expected.
- Pin-by-pin mapping of GX16 cable:
edited for clarity
(previously noted 1st Ring instead of Ring 2)
(previously noted 2nd Ring instead of Ring 1):
DigiRig 3.5 mm TRRS → FT-840 MIC/ACC
Sleeve ↔ Pin 7 (PTT) & headphone sleeve
Ring 2 ↔ Pin 6 (PTT return)
Ring 1 ↔ Pin 8 (AF out)
Tip ↔ Headphone tip (AF in)
Pins 1-5 → no connection
Wiring appears correct and matches published schematic.
4. Verified CAT control via single USB is working on tr(uSDX) with Unit #3.
Request
- Guidance on what may be damaging or disabling the RTS/PTT circuitry on the DigiRig when connected to the FT-840.
- Recommended additional measurements (e.g., voltage on FT-840 MIC pins) before I risk connecting Unit #3.
- RMA options for the first faulty unit if they are deemed defective.
Additional Notes / Questions
- Could voltage present on FT-840 Pin 7 or Pin 6 exceed DigiRig’s safe limits?
- Is there a firmware or hardware revision difference between early-2024 and mid-2025 DigiRig mobiles that might explain this behavior? My first DigiRig is a version 1.10. I didn’t look inside the second one that I returned. My current DigiRig is a version 1.11.
- I did submit a Support Contact Form on this site after my first unit failed and after a week I ordered the second unit.
Thank you for any assistance. Please let me know if you need further details.
Regards,
Bill