SL40 squealing on transmit

[spriteah]

Hello peoples,

Im having problems with a SL40 that sometimes (not always) has a high pitched squeal on transmint. It does not seem to be feedback. I have david clark headsets. It wont occur if both mikes are out.

Any idea's.

Jim.

[mikehoover]

I just started having this problem in the Cessna. Same transmit squeal from either seat. Using Bose in the left seat, and David Clark in the right seat. Not as bad once airborne, but on the ground it is horrible for us and whoever is on frequency. The same kind of squeal you hear in a bad public address (PA) system when someone walks up to the mike and it starts the loud feedback squeal. I look forward to hearing some comments. Thanks!

Mike

[craigvince]

I had the same problem in three different aircraft equipped with SL-40s. It turned out to be an incompatibility issue with my QT Halo headset. I've not had any issues with any other headsets. I did end up returning my QTs for this reason, which really bummed me out because I loved the Halo on every other radio. There's just something in the circuitry of the SL-40 that didn't like the circuitry of the Halo.

[SteinAir]

Check the coax cables first (if you have RV-58 with screw on connectors they almost always start as a culprit), next check all the jacks to ensure they are still insulated from the panel, check the wiring on the jacks (specifically the MIC jack) and then the wiring from the PTT to the jacks.

Typically if it's a gremlin type of an issue, one of the above is the cause.

Cheers,
Stein

[breister]

Also - if the headsets are the Noise Canceling variety check that you have fresh batteries. Weak (but not dead) batteries can have some interesting effects with some brands.

[lrfrey]

I had a similar problem with my SL-30, but it only happened on the co-pilot side. It also only happened with one particular head set.

After trying everything I could think of including talking to Garmin, adjusting gain in the SL-30, checking all connctions etc, I re-routed the antenna co-ax... presto-bingo! Seems that the co-pilot headset jack wires and the antenna co-ax didn't like being parallel to each other. Why only on one particular headset? - don't know. RF is funny stuff.

Only took me two days! ... good luck

Larry