Connect old non listed radio


Hi all, 

I am new to this but been trying to get my MFJ1234 working on radio not listed as has no serial or USB connection. I just want to use remotely on the one frequency so only need TX/RX audio and PTT.
I have set up the Rigpi program and it will transmit but no audio out from the Rigpi.. Using the Mumble app or in my case Plumble as I have a android phone, I can receive audio from the radio to my phone but can't get the radio to transmit on plumble even thou I can hear audio coming out of the TX Out port on the Rigpi using a headset to listen. I have tried using a iphone and I do hear the audio from that phone to my android and it also will receive audio out from the radio but as I cant get the plumble program to make the Rigpi transmit, no audio goes out over the air. If I use the Transmit button on the Rigpi program then on my phone push the Press to Talk, then audio comes out on the radio so there is an audio path there just need to get Plumble to make the pi transmit.
Is there something I am missing to get the TX Out PTT to work as I shouldn't have to use the Keyer PTT.

As I can't use the USB connections due to the type of radio, I have to use the Audio board connections. I am so close to getting it working but just cant get over the last hurdle. 
Any ideas.

David ZL2BA

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