Like in case of many mobile transceivers we’ll need to gather required signals from multiple connectors:
The audio must come out of the headphone jack, though there is a bit of a gacha there.
The amp uses a bridge-tied load (BTL) design while Digirig expects unbalanced input against the ground.
We can either:
- use an audio transformer from tip and sleeve on transceiver side to primary winding and from secondary winding to ground and RIG_AFOUT on Digirig side or
- just connect tip to RIG_AFOUT and leave sleeve unconnected on the transceiver side. This effectively halves the amplitude, but Digirig has enough sensitivity that this is not going to be an issue
So the final cable layout is like this:
RJ45 pin 1 (GND) → RJ45 pin 4 (MIC GND) - this may be not required and needs testing
RJ45 pin 1 (GND) → TRRS sleeve (GND)
RJ45 pin 2 (PTT) → TRRS ring 2 (PTT)
RJ45 pin 3 (MIC) → TRRS ring 1 (RIG_AFIN)
TRS tip (EXT SP1) → TRRS tip (RING_AFOUT)
TRS ring (EXT SP1) → NC
TRS sleeve (EXT SP2) → NC
Users-Manual-3731629.pdf (1.5 MB)
Are you using 2 TRRS plug or 1 and doubling up wire? I am hoping to adapt this to my BTECH UV-50X2.
Not sure if that’s your question, but you can use TRRS in place of TRS connector, just short unused ring to sleeve:
I folks, just had some success hope this helps AT-778UV Home Brew Cable or Box - Solved
This cable is now available in store:
Just got the marketing email for the new cable so this may be a bit late. On the “Up” pin /Black /5 on the connector, you can put an .1uf to 1.5uf capacitor in line to the mic/ audio in for the digrig, and set the radio audio out to “SpeakerMic”. When in this mode, audio out will go through this pin, but without the inline capacitor, it will just trigger the “up” button on what would be the hand mic. This will allow you to use a single cable from the RJ45 connector on front to the digirig for full PTT/audio interface without the need for the audio jack on the back.
Thank you for the information. Yes, that would make it a cleaner connection. Digirig has capacitors on both audio lines so there would be no need to add them in the cable. Will anybody be able to test the proof of concept for this cable variant?
I’ve actually been using this. Unfortunately I didn’t take any pictures during the build. But I just spliced an old Ethernet cable to a TRRS plug using your diagrams above along with the change on mine for audio out of the radio, and wired it to my digirig running in the standard configuration. It has been my go-to APRS / Direwolf interface.
It has been a while, so it would be nice for someone to confirm. My memory sometimes fails me.