MGL Avionics User Forum

I'm sure this has been done by someone but I am unsure how to correctly setup TX interlock between a V16 and a Garmin GTR200. The GTR uses a pin for interlock out and one for interlock in. The V16 uses a single pin for both. Surely tying the V16 pin to both GTR pins would not work, wouldn't transmitting on the GTR just lock itself out?

I have an audio panel involved, but that shouldn't matter. If I take the V16 PTT from the panel or the V16 and send that to the GTR TX interlock in and take the GTR TX interlock out and connect it to the V16 Interlock, would that work?

Like I said, someone somewhere has this working. I just need to know the right way to do it.

Thanks
Claude

I am not sure about the Garmin - worth a try though - in case of the V16 it looks at the pin and if allowed will start TX and at the same time output a signal on that pin (and of course ignore the state until the TX is completed).

I am guessing the Garmin will do similar so just give it a try - connect both together and see if it still transmits - if it does you can likely connect to the V16 then.

The easiest way:

PTT going to V16 from audio panel - splice a wire here and send it to TX Interlock in on the GTR 200
TX Interlock out from GTR 200 to single interlock pin on V16

Adam

Adam, that is what I was thinking would be easiest. Shouldn't matter if I splice that at the V16 or the Audio panel end, not that it matters much. I'm already running the interlock from the gtr to the v16, can just as easily run a pair.

Thanks both of you for confirming my thinking.

FlyingCanuck wrote: ↑Thu Jan 07, 2021 10:44 pm Adam, that is what I was thinking would be easiest. Shouldn't matter if I splice that at the V16 or the Audio panel end, not that it matters much. I'm already running the interlock from the gtr to the v16, can just as easily run a pair.

Thanks both of you for confirming my thinking.

No, it will not matter what end you splice at. For the more technical explanation, both the V16 and GTR 200 are looking for an active LOW signal to trigger the interlock. When the audio panel triggers PTT, it sends that low signal - this is how the GTR 200 knows that it should deenergize. The GTR 200 will send that same low on its output so that the V16 knows to de-energize. The V16, like the older Garmin 400/500 series navigators, listens and sends interlock signals on the same pin. For some reason, Garmin separated them on the GTR 200. I'm not sure the practical reason for doing so - but I think it may have to do with the fact that the GTN navigators do not have any kind of interlock pins, so if the in and out were on the same pin on the GTR 200, then the PTT in to de-energize the 200 would then trigger that PTT when the 200 wanted to command another radio to de energize.