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I’ve been trying different microphone combos with the microphone input and the thing is — I can’t figure out how to get the PTT on the mike line to work (running Dexx’s 4.2 btw).

The ring on the connector seems to trigger PTT when the signal floats, which I can get from just touching a wire connected to the ring. A normal PTT is a ground — what does this ring need to see? a specific voltage? is it sensing a resistance level? ?I note it seems to be running -2.4V…grounding doesn’t work… how can I trigger it from a button?

Or are there other ways to trigger PTT?

?

With some mikes like my motorola, the PTT simply connects the audio circuit, so I’d like to be able to sense that and send a trigger to the PTT.

Hi Charles,

The tip goes to microphone element, ring to the PTT switch, and the sleeve to ground. When you ground the ring (PTT) to sleeve (ground), the radio goes into transmit.

This is mentioned in

Hope this helps.

Happy New Year and 73,
Ragav
VU3VWR

You can find the circuit diagram on github in the sbitx/src/docs folder. :
You need to measure 3.3V at the ptt point, which is connected to the RPi input.
If you have problems with the microphone, you can find a solution on the , many people have implemented it and replaced the microphone insert.

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Gyula HA3HZ