Icom 705 to APRS.fi iPhone App

Question

I would like to use the Software Modem included in the APRS.fi iPhone app, together with my IC-705.

Simply tuning to 144.800 (here in Europe), putting the AF on speaker and letting the iPhone app decode it with the microphone works better than expected, but is of course less than optimal.

My iPhone has a Lightning connector, and there exists accessory like the Lightning to 3,5mm Audio adapter. But what would be the right way to directly connect the Speaker and Mic output of the IC-705 to the Lightning audio input on the iPhone? And can this be used at all for TX, too?

Answer 1

There are a few aftermarket 705 headset adapters that split out into various phono jacks. The lightning to 3.5 adapter is in a TRRS configuration, and I believe you should be able to get an off the shelf TRRS splitter into 2 plugs (otherwise, DIY this is pretty trivial).

You could rig up some PTT mechanism, but I'd personally use the VOX feature for a proof of concept and then decide it's good enough and never implement the PTT.

You'll want to start out with relative volumes on both devices at zero and gradually inch up so as not to blow out any circuitry.

If you want to get really fancy, you could run everything through an audio mixing board and manage the levels with slide controls that would make a DJ jealous. Maybe get some neon underlighting. Smoke machine. etc.

Anyway, this would make all audio channels run directly between the phone and rig. For TX you'd need to find an appropriate app on the phone that would send desirable transmissions to the rig.