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Old 11-16-2020, 07:24 PM
jimgreen jimgreen is offline
Join Date: Apr 2006
Location: Vancouver island, BC Canada
Posts: 389
Default SL40 no transmit

Before I start spending money I thought I'd ask here. I would have to fly using a handheld to get to a radio shop.
I have an SL40 that no longer transmits - receive is fine.
The 'TX' displays as normal on the front with ptt pushed on either side, but no signal. Two Zulu headsets, two ptt switches, same symptoms with any combo.
What should I look for?
Seems that if I have TX showing it should be transmitting.
Jim Green
RV7 tip up
IO360 Whirlwind 200RV
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Old 11-16-2020, 08:21 PM
BobTurner BobTurner is offline
Join Date: Dec 2011
Location: Livermore, CA
Posts: 7,151

You don’t say if the two mic’s are fed to the radio thru an audio panel or switches or intercom (and does the intercom work).
Borrow a handheld or enlist a pilot friend with a receiver. When trying to transmit do you hear ‘Carrier no voice’? If so you should check out all the mike wiring. If no, it’s probably off to the avionics shop.
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Old 11-16-2020, 08:26 PM
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PaulvS PaulvS is offline
Join Date: Aug 2019
Location: Western Australia
Posts: 513

Here's a couple of suggestions without spending any money:

Can you hear the carrier and PTT click on another receiver?

If "yes", then fault is possibly a bad connection on the mic input to SL40. Try checking and reseating the D-sub connector to the radio.

If "no" carrier then check connections to antenna. If there's nothing wrong then next step may be to the avionics shop...
Paul vS (yes I'm also a Van)
Building RV-6A #22320 O-320 FP. Wings and tail complete, working on fuselage
Flying my Aeroprakt A-22 STOL and the aero club's RV-9A while I build
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Old 11-17-2020, 08:13 AM
jimgreen jimgreen is offline
Join Date: Apr 2006
Location: Vancouver island, BC Canada
Posts: 389

Thanks for the replies. Forgot you can't read my mind, I have a functioning PM1000 intercom. The symptoms are the same with intercom on or off.
Will check further today.
Jim Green
RV7 tip up
IO360 Whirlwind 200RV
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Old 11-17-2020, 08:34 AM
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Larco Larco is offline
Join Date: Mar 2005
Location: DVT Phoenix
Posts: 1,223

I actually had the same symptoms some years ago, carrier but no voice. PM1000 with a Narco. Sent the radio in for repair and was told Radio is good, sent intercom into PSE and they found a bad relay which was supposed to work with intercom off or on. They said that this is a very rare failure item which is supposed to keep the radio active when the intercom fails. Replacement of the relay fixed the problem. Years ago some builders would add a third set of jacks in the system for the purpose of diagnoses, IIRC PSE recommended it as an option. Hope this helps and a call to PSE might be helpful. Of course this story could turn out to be irrelevant in your case but it drove me nuts at the time.
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