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simple PTT/audio interface

Posted: 18 Mar 2018, 20:17
by welshevo
im looking for a simple PTT/audio interface to pass audio from zello through a Sepura SRH (side connector audio accessories port) radio but cant seem to find any info on pin outs etc? do Sepura use the same pin outs as the Motorola MTH side connector? any advice would be amazing....

Re: simple PTT/audio interface

Posted: 04 Jul 2018, 09:35
Audio port pin out is here: ... als/sepura

If you download the pin out, it becomes an "orphan" document. Scan the QR code for the latest version (as I find anything interesting, I add it to the website).

Do NOT connect these handsets to other devices whilst on charge. You'll create a ground loop, which means at best, you'll get buzzing noises on the audio. At worst, you'll kill the audio on the handset.
Research audio transformers and relays for the interface. I use 1:1 600ohm audio transformers exclusively. Opto-isolators are solid state alternatives to relays for low current switching.