Cabin leaks slightly during only the heaviest rain storms. We haven't been
able to find the leak. Not very wet, could have just been high humidity,
not sure.

Full story if nothing more than for the archives and to jog my memory:

Airplane sat on the ramp at Key West a couple weeks ago while they got over
3" of rain during some pretty heavy storms. Islands to the north got up to
10" during the same period. After the rain stopped I went out to the
airport to check the plane, noticed several drops on one of the vertical
cabin support posts ahead of the pilots window. No wet carpets, no dampness
or free moisture on the glare shield, no other water noted anywhere, but
when I checked the avionics the #1 nav lit up with 188.88 on active and
standby. When I turned the speaker on, nothing but static coming from the
nav side of #1, same thing through headsets.

Pulled both #1 and #2, no free moisture noted in the trays or on the radios
or connections but it felt like 110% humidity in the cabin. Took #1 back to
the hotel and placed it in front of a fan, no heat, for approximately 10
hours. Reinstalled it in the #2 slot before we departed, no static, nav now
displayed normal, operated normal. Flew home with #2 in the #1 slot driving
the autopilot. Refueled at Eufaula, AL after 3+ hours. Everything normal.

Refueled again in Champaign, IL after another 3+ hours, everything normal
until we leveled off after climb out. Then #2 in #1 slot started the
pitchdown when transmitting with alt hold thing. Not severe, just a mild
pressure on the yoke, but noticeable. Checked transmit on the #1 com (the
wet one) in the #2 slot, no problems. Checked Nav vs Hdg mode on the
autopilot, pitch down in either mode. Checked GPS vs VOR, pitch down when
coupled to either source.

Swapped them back to original locations after we got home. Next day flew
some approaches with a friend, local tower complained of heavy static during
transmissions from the #1 (wet) com. No pitchdown with this radio noted.
No complaints of static prior to Key West flight.

So I've got static on #1, and #2 causes pitch down, but no static, when
installed in the #1 slot.

Jim