3.5mm Male TRRS Digirig Side (Audio) ↔ 3.5mm Male TRRS Radio Side
Tip (RIG_AFOUT) → Ring2 (SP)
Ring1 (RIG_AFIN) → Ring1 (MIC)
Ring2 (PTT) → Tip (PTT)
Sleeve (GND) → Sleeve (GND)
The straight through cable can used for programming the radio with Digirig:
3.5mm Male TRS/TRRS Digirig Side (Audio) ↔ 3.5mm Male TRS/TRRS Radio Side
Tip (RIG_RXD) → Tip (RX)
Ring1 (RIG_TXD) → Ring1 (TX)
Ring2 (3V3) → NC
Sleeve (GND) → Sleeve (GND)
This post was extremely helpful. However, I struggled for quite a bit longer than I wish I had due to the fact that I was plugging into the Data port or Programming port as listed in previous comments, instead of the Speaker/Mic/PTT Port in the back of the radio. The actual port you must use is the left most 3.5mm which is labeled Speaker not Data. I found that the original pin out in the manual was correct for the 8900D that I have & not switched per the shared PDF. However, who knows how yours will be when it’s an $89 radio. Just depends on which blind Chinese orphan is assembling it I suppose.
After some considerable testing I have concluded that QYT is just not designed thoughtfully enough nor supported adequately for my needs. Apart from the port not responding correctly per factory pinout, it didn’t program per instruction nor would brand name or CHIRP program the radio. I returned it in favor of another platform that has proven reliable in the past.
Anyone have any luck getting the PTT to work? I was able to use the video above from K0TX to show that the digirig is sending the RTS signal (i.e., I get resistance readings on GND (sleeve) and PTT (tip) when testing from WJSTX).
However, plugging the cable into the radio doesn’t seem to work – even if I do the by-hand test of touching a wire to both the sleeve and ring 2 of the digirig side of the cable.
I’m at a loss about what else to do. I’m hoping to use this radio for a mini digital-enabled manpack. If it is entirely a lost cause, I’ll ditch the digital stuff and just use it for audio (it was cheap enough), but if it’s just a case of maybe sending this one back and getting another one, I’m willing to do that.
It would be surprising if the pinout info from the transceiver’s documentation was incorrect. If simulated PTT doesn’t work via the homebrew cable I’d double check wiring and made sure you didn’t reverse the ends between Digirig and transceiver - easy to do with same type connectors on both ends.
Thanks, but I double checked this both with probes and by reversing the cable.
I’ve gone ahead and requested a replacement since the radio also won’t transmit on 70cm. I don’t expect much from an $80 radio, but that seemed a bit too far.
Yep, tried both to no avail. Mostly focused on #1 as that’s the one that’s supposed to work for this purpose, but I did give #2 a go. The #2 (“Data”) port is for programming, which did work just fine, I was able to get Chirp to read/write from the radio no problem.
FYI, I got a new QYT radio and the cable worked! (It still won’t transmit on 70 cm, so I may swap out a different radio anyway). Oddly enough, shorting the pins did not work, but plugging in the whole system with the Digirig and triggering a PTT with WSJTX worked like a champ.
So, for anyone reading this in the future, you can get PTT to work with the above wiring on the QYT KT-7900D; if it doesn’t work, it might just be a bum radio (as people above have implied).
I think I solved the mystery why some have PTT working and others do not. How thick is the insulation around the base of the TRRS you are plugging into the radio? The chassis has a very narrow hole. Turns out the insulation on my cable would not let my cable plug all the way in. As tip is PTT, if it isn’t fully seated, PTT doesn’t work! Shave back the insulation half an inch back and voila, goes right in and everything works!
Same thing with Baofengs…you really have to jam those cables in there as it is very tight and the in there as the plastic housing around the cable often interferes with the small cutout on the chassis.
