MAS 835 Aircraft radio

[skywarrior]

Hi All,
I came across 3 of these radios but none have microphones so there is no audio available thru the speaker. These are rather obscure radios but they are great receivers if you have the microphone or know which connections to junction. I was wondering if anyone might have any information on these radios or the proper way to activate the speaker?
TIA
Bruce

 

[merlin]

Don't know much about this particular radio, its vintage.
I know the mic connector is wired for an optional headset.
You could try using a speaker, one side grounded, the other, probe the pins for the audio to headset.
Then an ohm meter to find the pin to the speaker (4-8 ohm)
Once found, jumper the 2 pins.
There will be a PTT line, if grounded, the radio will transmit. Possibly a bias for the mic input also.
For programming, you need an eprom burner, UV eraser, and an old DOS program.