APX Remote Speaker Mic RSM

[mustanglane]

New to APX radios (actually have not touched one yet) but have EXTENSIVE experience with XTS (including CPS, XTVA, etc)
We are trying to determine how we could interface the APX to an aircraft intercom system. From the Detailed Service Manual, it appears that MIC Audio and RX Audio are available from the GCAI Side Connector, but there is no obvious PTT line. Been searching for information on any potential hookup (including Moto Online) but so far, nothing. I do see where the radio self-determines what the accessory is that has been connected, and am worried that this will not be possible as it was with Saber, XTS etc. Also, it looks as if Moto has not (yet anyway) created a Vehicle Adapter like the XTVA.
Anyone have any thoughts? We have the PMMN4062a replacement cable - just need the PTT pinout if it is even possible---
Thanks!

[Bigfella237]

~ I do see where the radio self-determines what the accessory is that has been connected ~

I think this only relates to accessories with a one-wire chip in them (so-called IMPRES accessories and programming cables etc.)?

I can't answer your main question as I have no experience in the aviation field but I doubt we will ever see an "APVA" (my guess on the name), I'd think it would be available by now if it was forthcoming, but there again, they haven't managed to get a basic thing like QCII into an APX yet so really it's anyone's guess?

Andrew

[pluto1914]

Were you able to find out how to get the PTT on the accessory connector? I have a similar project coming up.

David

[mustanglane]

Not yet - a Moto Service Tech that I also have contact with provided a diagram that suggests Pin-9 is the PTT, but we tried it and it did not work. As we only have the replacement cable for the remote Spkr/Mic, we dont know which wires go to PTT - IF IN FACT ANY do. I could really use a schematic of the internals of the MIC, cause I'm afraid that there is circuitry inside there that works the PTT and its not directly related to a switch actuation (not sure if that is clear, but in other words, it may not be possible to simply key the radio by grounding any of the existing side terminals - )
IF I get an answer outside of the Batlabs, I will certainly post it -
Regards,
DDG

[mustanglane]

Solution Found!
One of our contract Aircraft Avionics Techs made an adapter cable as follows:

This solution creates an interface cable between an APX series radio and a Bulkhead Cannon-Plug Style connector that exists in many DHS aircraft and is normally utilized to install an XTVA.
1. Acquire a PMMN4062 lapel mic for the APX portable radio.
2. Strip the mic down to the pc board, leaving the IC containing the "one wire" data still intact and tricking the radio.
3. This Mic unit has an external 3.5 mm audio jack for an earpiece that cuts out the loudspeaker on the lapel mic. Tap into the audio there with a 3.5 mm plug and bring the phone audio + and - out.
4. Remove the dynamic mic from the ribbon cable (along with the bridging resistor), and solder a wire into the + and - holes of the ribbon cable traces to bring out the Mic Hi and Lo.
5. Leave the mechanical PTT switch in place and simply bridge around it with a 12 micro relay that is powered with aircraft A+ available at the XTVA cannon plug. The - side of the coil was brought out to the cannon plug and the relay is triggered by the existing PTT line.

The whole thing is mounted in a plastic project box from Radio shack. There is a length of RG170 from one end to the other passing through the enclosure which was planned to connect the radio to the external aircraft VHF/UHF antenna. As an alternative, use an SMA Female to BNC Female, P/N RF8381, to directly attach the antenna to the top of the radio.

I have pictures that show a PROTOTYPE creation. Cant seem to paste them here though - Plans are to formalize the build for additional distribution to other DHS Aircraft units!

[resqguy911]

Solution Found!
One of our contract Aircraft Avionics Techs made an adapter cable as follows:

This solution creates an interface cable between an APX series radio and a Bulkhead Cannon-Plug Style connector that exists in many DHS aircraft and is normally utilized to install an XTVA.
1. Acquire a PMMN4062 lapel mic for the APX portable radio.
2. Strip the mic down to the pc board, leaving the IC containing the "one wire" data still intact and tricking the radio.
3. This Mic unit has an external 3.5 mm audio jack for an earpiece that cuts out the loudspeaker on the lapel mic. Tap into the audio there with a 3.5 mm plug and bring the phone audio + and - out.
4. Remove the dynamic mic from the ribbon cable (along with the bridging resistor), and solder a wire into the + and - holes of the ribbon cable traces to bring out the Mic Hi and Lo.
5. Leave the mechanical PTT switch in place and simply bridge around it with a 12 micro relay that is powered with aircraft A+ available at the XTVA cannon plug. The - side of the coil was brought out to the cannon plug and the relay is triggered by the existing PTT line.

The whole thing is mounted in a plastic project box from Radio shack. There is a length of RG170 from one end to the other passing through the enclosure which was planned to connect the radio to the external aircraft VHF/UHF antenna. As an alternative, use an SMA Female to BNC Female, P/N RF8381, to directly attach the antenna to the top of the radio.

I have pictures that show a PROTOTYPE creation. Cant seem to paste them here though - Plans are to formalize the build for additional distribution to other DHS Aircraft units!

Thanks for the hard work. You need to host the pictures somewhere (picasa, imgur, flickr etc) and link to here.

[mustanglane]

OK - first I have to state very openly that I didnt come up with this myself! I did a lot of research for the individual who did, but, it was his creation (Not a Moto guy---)
Anyway, lets see if the pictures work from imgur----

or this way
http://imgur.com/iBzBENt http://imgur.com/zLRQD88

My first time with imgur-----