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PS Engineering PM1200

D Weisgerber

Well Known Member
I have a PS Engineering PM1200 that I just installed along with an ICOM A200 radio. When I try to transmit through the intercom I don't get anything even though the TX is on the radio, but the intercom works. When I switch my headsets to the radio only jacks I get a good radio check. Any ideas on what I should check?
 
I installed a PM1200 including intercom PTTs. I have a schematic. Let me look it up and send it on.
 
Take a look at the attached. You can ignore the ICS PTT circuits if you are not using them. This was for use in a Husky flying with the doors and windows open so we had get rid of the vox intercom squelch in that configuration so the ICS could switch to the PTT mode with separate PTTs for in-cockpit coms.

The two areas to pay attention to are circled in red. Specifically the pilot and co-pilot PTT circuits in the lower portion where the other side of the PTT goes to ground. The second place to look is in the red circled area in the upper portion of the diagram. Make sure the radio key circuit is connected properly to the VHF Com radio.
 

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I have a PS Engineering PM1200 that I just installed along with an ICOM A200 radio. When I try to transmit through the intercom I don't get anything even though the TX is on the radio, but the intercom works. When I switch my headsets to the radio only jacks I get a good radio check. Any ideas on what I should check?

I have the same setup and having exactly the same issues. Have you resolved this problem? Just curious if the advice in this thread produced positive results. Thanks!
 
I did fix it, the PTT switch has to be connected to the AUX mic jack. I had it hooked up to the pilots jack.
 
I did fix it, the PTT switch has to be connected to the AUX mic jack. I had it hooked up to the pilots jack.

Per the PM1200 installation diagram one set of PTT switches are to be connected to the headset jacks, and one set to intercom pins, not the jacks. So it is important to understand the PM1200 has two sets of PTT circuits. One for standard VHF com transmit PTT, Pins 24 (pilot) and 22 (copilot), grounding to the audio ground at the jacks. Then there is another set of pins for internal PTT intercom so the crew can talk under high noise conditions without the VOX squelching out Pins 16 (pilot) and 15 (co-pilot). These get grounded by Pin 2 of of the ICS. Basically a second set of PTT switches for cockpit crew communication. This second set of PTTs for cockpit communication should not be necessary for most RVs. I use them for open-cockpit or open door bush planes with lots of air and engine noise or noisy warbirds.

Only Pins of the intercom should be connected to the com radio (either at the radio or main radio standby AUX headset/mic jacks). No external PTT. So the PTT buttons only ground the ICS jacks and then the ICS "keys" the com with via the com's PTT key wire and only sends the mic audio to the com from the position that pressed the PTT. If you hook up the PTT to the AUX mic jack you will be bypassing the ICS mic audio for transmit and probably both positions will be "hot" on transmit.
 
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