Cable for First Gen BTech 50x2


Any advice on how to piece this cable together? The first gen 50x2 has only a TS Line-Out connector in the back, and not the TRRS like the new version. It is compatible with TS Mono Speakers.

So I know I’ll need to splice a TS and RJ45 together into a TRRS for the digirig but I wasn’t 100% sure on the connections to make. The RJ45 pinout looks like this:

  1. Data Input
  3. MIC
  4. MIC Ground
  5. PTT.
  6. GND
  7. +8v DC Out
  8. Null


The connections to Digirig’s audio socket should be something like this:

RJ-45 pin 3 (MIC) → 3.5mm TRRS ring 1 (RIG_AFIN)
RJ-45 pin 5 (PTT) → 3.5mm TRRS ring 2 (RIG_PTT)
RJ-45 pin 6 (GND) → RJ-45 pin 4 (MIC Ground)
RJ-45 pin 6 (GND) → 3.5mm TRRS sleeve (GND)
3.5mm TS tip (SP) → 3.5mm TRRS tip (RIG_AFOUT)

Thank you for the reply. I gave that a try but it’s making the radio power cycle over and over. Any idea what that could indicate?

Try disconnecting:
RJ-45 pin 6 (GND) → RJ-45 pin 4 (MIC Ground)

If that doesn’t solve the problem try removing other connections one-at-a-time until radio returns to normal function.

I have a 50x2 1st gen. Did OP get your cable pinout worked out?

Yes, K0TX’s suggested pinout was correct. The issue I was having was due to a mistake on my end.


Can I ask what you are using your 50x2 for? I’ve tried APRS but it’s just not hearing anything.

I made a cable. Great continuity through each line. The 50x2 gen 1 hears APRS traffic, but doesn’t pass it along. The digirig drivers are properly installed, and found as a port. It is selected as speaker and mic. I’m running APBK. The program works great with my Yaesu FT-65.

Anybody have any suggestions?

Congratulations on making your cable! There is a guide, Troubleshooting Digital Modes – digirig which can help in this situation. For instance, do you have the serial port driver installed for your operating system?

73 Constrainted

Like I said the Yaesu works splendidly on the same PC. So that rules out digirig issues. Crossing that off the list for potential issues. Now to check the cable again.

That’s great the FT-65 is working.

  1. test PTT function – when using hardware PTT line you can test it by shorting the signal to the ground on the jack that would go into Digirig. This should switch radio to transmit. Some HT cables have a PTT button which should also work the same way.

Or is the problem no audio out on TX? Are you monitoring on the FT-65?

73 Constrainted

Dennis I don’t see the speaker ts sleeve going to anything? So the speaker line doesn’t have the negative connected to the trrs?


There are two possibilities for headphones’ sleeve, and in either case that line is ok or better off not connected:

  1. it’s connected to radio’s chassis and in that case it’s redundant because there is already ground connection to Digirig via the mic connector

  2. it’s one leg of the BTL amp and in that case connecting it to GND/chassis can damage it.

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Constrained! Thanks so much for your help! We got it working. I recognized I had an open ground line in the rj45 plug that wasn’t going anywhere. It was the 6 that is supposed to be tied to 4. I rebuilt the cable because there was another variable that needed removed because of where I bought the cable I was customizing. After rebuilding and reading your last follow-up I found the mic and the ptt lines in the rj45 were backwards going to the trrs. After I reversed those 2 it is working as it should.

Thanks so much!

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@Adam Thanks for reporting the good news! My advice was cut-and-pasted from @K0TX 's troubleshooting guide. Have fun with the BTech.

73 Constrainted

Just wanted to give an update on my progress. After troubleshooting the cable, fixing the problems, and testing with APBK-Gate, I’ve made really good progress. I now have the old Gen 1 Btech 50x2 with the Digirig Mobile up and running on a fresh Linux Mint install with Direwolf. Lots of doors now open to research at this point!


@Adam Congratulations! That’s great news. Now I am going to go find out more about APBK-Gate myself.

73 Constrainted

Its a very small windows app. I just used it for equipment testing. Quick and easy to put up.

I believe this particular project has entered the maintenance and tweak phase. I’ve got YAAC running on top of Direwolf.

I certainly appreciate the positive encouragement, feedback, and quick responses. Really kept me motivated to see this project through.

Great! YAAC opens up many of the possibilities for messaging with APRS, once you know the gateways.

73 Constrainted

Glad to hear you got everything working! It took a bit of messing around for me too, but once you get it, the digirig works well with this radio and direwolf.

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