Digirig + Baofeng Black Cable- no PPT

Hello All:

Using a Pi Zero W and DigiRig to run a Baofeng UV-5R. Got the Baofeng cables (Black & Green) and using the black cable to go from DIgiRig to UV-5R. When I try to TX, no transmit from HT. When I use Dennis’ earlier trick to short the DigiRig Audio plug S to R1, still no TX on HT; no PTT. Cable shows connectivity between Audio TRRS and Black connector pins.

Tried a Kenwood TH-F6A as well (Kenwood K1 connector) but no TX there either. PTT signal levels? Any other thoughts?

Thanks - Jeff Marden/N1JCM

If cable connectivity checks out with the schematic in the product page, but you get no PTT from shorting the sleeve to the closest ring (R2 actually) then the issue is either connection to the radio or radio itself. Do you have any other accessory for this ration that support PTT? Like a speaker/mic.

Thanks for the follow-up. R2 = PTT on the audio connector - Corrected!

I have tested both the Baofeng and the Kenwood with SP/Mic’s and a Mobilink TNC3 in the past, but not recently, so I will do this again and report back.

Thx - Jeff Marden/N1JCM

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Hello Denis:

Upon further investigation…

I plugged the Baofeng SP/Mic into both the UV-5R and the Kenwood TH-F6 and it worked as expected; radio keyed when the PTT button was pushed. Still no TX with the DigiRig and black cable.

I took the Baofeng mic apart and followed & measured the PTT circuit. Most notable is that the PTT signal from the radio is pulled to 3.3vdc via a 10K resistor in the radio ( as shown in the Baofeng UV-5R schematic). When in RX, the PTT signal measures 3.3vdc at the sleeve of the 3.5mm plug. When the PTT switch on the mic is pressed, this PTT signal is pulled to GND (and the radio transmits).

When I plug the DigiRig black cable into the Baofeng (or Kenwood TH-F6 and measure volts at the TRRS male plug, the PTT signal on R2 is not pulled to +3.3vdc; it appears open. My digital ohm meter shows continuity between TRRS Sleeve and 2.5mm sleeve/GND, and between TRRS R2 and 3.5mm sleeve/PTT. Again, when I short TRRS Sleeve and TRRS R2 together, no TX/PTT.

Any further thoughts?


Jeff Marden/N1JCM

Nice troubleshooting. So we know the cable has continuity, but there is no open PTT voltage on Digirig’s side of the cable. This would suggest a bad connection. Do you see any difference in the contacts size or molding between the K1 connector of the speaker/mic and that of Digirig?

You should also be able to check the connectivity between the sleeve on the Digirig’s connector and the radio’s ground without taking it apart (say at antenna).

Hi Denis:

No obvious differences between the SP/Mic connector and the DIgiRig Black cable radio connector.

I did check continuity between the radio GND and the black cable TRRS sleeve GND - none.

However when I stressed the black cable radio connector in its radio socket (pressed it in the socket) I did get continuity, and when I did this with the radio on I measured the 3.3vdc on the TRRS R2 PTT ring.

Looks like some mechanical issue between the DigiRig Black Baofeng cable radio connector and the radio socket @ GND.

Not sure what else to do, but thanks for the help!

Jeff Marden/N1JCM

How does the molding compare. There is a possibility that the molding prevent full insertion. That can be trimmed back if needed. If cable is somehow flaky, I can replace it.

Hello Denis - the molding on the cable looks good. I can see the two pins of the radio black cable all the way down to the gold base section, so no obvious problems with the connector interfacing with the radio. I have now tested on the Baofeng UV-5R, The Kenwood TH-F6A and the Icom W32 (which uses the same K1 connector) without success.

I can’t say if this is a flakey cable or not, but if I could get another black Baofeng interface cable to test that would be great. I would agree to return it if there is no change in operation.

Thanks - Jeff Marden/N1JCM

Ok, I’m going to shoot you another black K1 cable when I’m back in office next Monday.

Much appreciated - I’ll update when I test this new cable.


Jeff Marden/N1JCM

I have a number of Baofeng HTs. It’s pretty well known that the quality of them is pretty lacking. On some radios, you really have to push the K1 connector in pretty hard. Enough to eventually cause damage. I put those ones in a pile and avoid using them for digital. I search until I find one that doesn’t do that. YMMV.

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Yes, I lost quite a bit of time when I first started with the Baofeng HT by not pushing the Kenwood connector firmly into the socket.