Kokemiller

Kokemiller

Well Known Member
I have an Icom A200 and flightcom 403mc,
it receives great,
can talk back and forth between pilot and co-pilot through the intercom,
music input comes through loud and clear via music input,
but as soon as you press the PTT there is no side tone and no transmiting even though though the TX is lit up on the radio.
Any advice is appreciated.
 
no xmit on a200

Had some trouble with this myself when you transmit you hear a dull thud this is a short between the mike and ground. I found the diagram to be hard to follow. I pulled everything out of the plane and rewired it on the bench as per diagram and no xmit when i grounded the mike circut through the ptt heypresto xmit. You are feeding the energy into the groundplane to leak out through the antenna so to speak. I hope this helps.

cyril rv8a
 
I agree it does seem to be a ground issue but everything is wired according to diagrams, nothing obvious. I hate electrical troubleshooting!
 
I had the same situation on my old PA-22 equipped with an A200, ie, transmits fine but no sidetone. The Icom phone tech instructed me to pull the radio from the panel. Peel off the circle of tape on top of the radio. Use a tiny plastic screwdriver (borrowed from your local avionics shop) to adjust the sidetone volume pot to about halfway or higher. He said this sometimes gets overlooked at the factory.
It didn't work for me as my volume was already factory set at the max level. So I just got used to not hearing myself in the headset. And you know, I really kinda liked it after a bit.
Note: I was using one of those velcro add-on PTT buttons so I was not exactly following the wiring diagram in that regard.
 
maybe the PTT bitton or wire.

I had a similar problem. All seemed fine until I hit the PTT switch. Then nothing. The TX indicated I was transmitting but the tower did not read. No side tone.

I found the problem to be a worn through wire in the control stick PTT button. I replaced the wire and all worked well.
 
Ummmm......

Ummmm..... Plug the Mic in? :rolleyes:

Yeah, I know, everyone would think of this first. However, back in the day, lo these many years ago, I troubleshot and fixed old tube-type TV's. About one out of ten house calls for TV's that didn't work were "signed off" by plugging the TV in to the wall power socket!:eek:

Try the stupid stuff first, and the cheap stuff second!
 
Kelley,

The exact same problem (symptom) was discussed in an earlier thread http://www.vansairforce.com/community/showthread.php?t=47581. His problem/solution turned out to be:

Specifics: The ring terminal on the Van's cable (RZ1) and pin 17 on the Flightcom intercom was not stripped cleanly to the center conductor. The terminal was crimped over the shield thus grounding the transmitter output. Just poor workmanship. The heat shrink terminals were pretty ugly too, but functional.
Click to expand...

Would be surprised if you had the EXACT same problem but who knows.
 
problem found

Pacific coast avionics fabricated my wiring harness and said they bench tested everything, so I assumed it was the wiring that I hooked up incorrectly. After tracing and checking continuity on each wire in each harness I found wires H and 9 were transposed. I swapped the wires and it looks and sounds like it should, just need to check with a handheld for tx and rx.

Just wonder how it passed the "bench test".

Thanks for the replies
 
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I pulled the A200 out of my Corby Starlet and it was working OK. Put it in the RV4 and can't transmit.
Looking at the wiring diagram, I cannot understand how to wire in the PTT. It is shown as the wire from Pun 9 to the mike jack, goes to PTT switch. Does the PTT get installed in this wire, or does it go to earth somewhere.
Am I correct in assuming that the shielding wires go to the base of the jack, the 600 ohm wire from pin J or K goes to the ring ( middle connection) of the jack and the PTT wire from pin 9 goes to the tip connection?
Must have brain fade as I wired it up originally in the Corby but that was 11 years ago.
 
Yen said:
I pulled the A200 out of my Corby Starlet and it was working OK. Put it in the RV4 and can't transmit.
Looking at the wiring diagram, I cannot understand how to wire in the PTT. It is shown as the wire from Pun 9 to the mike jack, goes to PTT switch. Does the PTT get installed in this wire, or does it go to earth somewhere.
Am I correct in assuming that the shielding wires go to the base of the jack, the 600 ohm wire from pin J or K goes to the ring ( middle connection) of the jack and the PTT wire from pin 9 goes to the tip connection?
Must have brain fade as I wired it up originally in the Corby but that was 11 years ago.
Click to expand...

When the PTT line (pin#9) gets grounded thru a pushbutton switch, that's what keys the transmitter. The tip connector of the mic jack has historically usually been connected to the PTT line in most general aviation aircraft... this comes from the days of your typical rental "spamcan" planes that often get portable intercoms plugged in and temporary PTT switches velcroed to the yoke, etc... also if you plug in a handmike, its PTT switch will be able to key the transmitter.

Personally, I see little use in connecting the PTT line to the tip contact of a mic jack in an RV anymore, since we pretty much all have PTT switches hardwired and installed in the control sticks. So that's my recommendation, just ignore the tip contact of the mic jack and wire your PTT switch(s) straight to the radio or intercom if you have one. The mic transmit audio (ring contact on the jack) goes to pin J on the radio (or the appropriate mic input on your separate intercom.

BTW, an outboard intercom is highly recommended for use with the A-200, the built-in intercom is absolutely horrible and would force you to share one single intercom mic input connection between two mics, and to really do that right would require a confusing hodge-podge of relays and/or switches to be wired into the circuit with "push-to-intercom" buttons needed for both seats.

Of course if you have an RV-3, no intercom is needed and you can get away with just the radio and a set of headset jacks :D
 
Thanks Neal. I will rewire not using the tip contact. that will save having to run wire through 2 bulkheads.
 
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