On Feb 26, 9:38 am, "Jim B" wrote:
Can someone explain a com radio's Standing Wave Ratio?

During our trip to Key West, our #1 KX155 got damp. I removed it, dried it
out, and just to be safe, swapped places with our #2 KX155. After several
hours of flying and just after take off from Champaign IL, we noticed that
when in altitude hold mode our Stec 60-2 would enter a slight dive when
transmitting on the #2 com (now in the top slot). This happened when in
either Nav or HDG mode and when coupled to either the VOR or the GPS. I
found the following on Stec's web site and am looking for a little
education.

Q: Where do I start when the aircraft either climbs or dives when the mike
button is pressed to transmit?
A: Over the years it has become customary to place the autopilot at the
bottom of the radio stack. Check the standing wave ratio on the comm.
radios, a high S.W.R will affect the altitude transducer. Make sure the coax
cables are routed away from autopilot wiring, and check for proper antenna
bonding.

Thanks as always,

Jim

The guys responding are very helpful and this list is good for that. I
have a couple of questions, How did the radio get wet and how wet???
Just curious,,,,