Whine on transmit

Just got my DAR approval today, have not yet flown my RV-12.

While doing taxi tests I have a significant "whine" when transmitting as a feedback into the ear phones. Don't know whether receioving radios hear this, but I assume so. Any ideas as to the likely culprit? Any thoughts appreciated!

Doug Dahl
RV-9A, RV-12 ready for first flight

Doug,

I'm assuming this is an alternator whine, not feedback. There have been a few threads on this, or similar problems. If the whine is showing up on transmit, not receive, a likely culprit is the mike jacks. Be sure the isolation washers went in as specified to prevent ground loops.

John

Whine

John
Thanks. I'll take a look.
Doug

It's probably just a jealous Cessna owner on frequency... "But MOM... I want an RV too!"

Maybe sidetone is too high?

Could be your sidetone is adjusted too high in the radio. If you go into the radio settings you can adjust it. A setting of zero slaves it to the volume control.

Could it be the dog?

Doug, Get a copy of the electrical schematic for your 12. Study how the intercom is wired in with your 12 configuration, SV or D180, make sure the pin outs and ins for the wiring harness from the comm to the back of the intercom are correct. As mentioned earlier on a post, make sure by the construction manual Sect 31 jacks are installed and grounded/not grounded properly. I found multiple pin outs in error and redid the harness by using the ele. schematic and all my troubles went away. It only took me 6 months and help from every one on VAF to get it right. If Vans would have included the schematic with one of the kits, I would have been flying a lot sooner. Good LUCK

Doug Robison

Whine

Thanks to all. I adjusted to sidetone to 000, per Andy J (thank you!) and the whine is gone. transmissions are 5x5. First flight planned for tomorrow, 21st.

Doug

One more thing...

Everyone should check to make sure they don't use the insulators on the headphone side. The kit comes with them but the plans do not show you putting them on. I had a similar problem early on and sidetone helped but the second I removed the insulators the problem was gone.

"I found multiple pin outs in error and redid the harness by using the ele. schematic and all my troubles went away. It only took me 6 months and help from every one on VAF to get it right. If Vans would have included the schematic with one of the kits, I would have been flying a lot sooner."

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There have been quite a few of these pinout errors posted. Makes me want to think I'm gonna checkout every harness I have. They all come with the Steinair pinout diagram. Unfortunately, the diagrams also all come with a prominent PASSED notation.

Also, it would be nice if Vans would release the Wiring Diagrams without the big "WARNING - Reference Only - Do Not Use" callout above the plate block. I, too, find the wiring diagram invaluable for wiring up my ship.

Bob Bogash
N737G