Interesting problem. I have a Narco a Mark 12D and just a digital Narco COM. After flying through a rain both radios will not transmit. Just get a static noise. I can hear controllers OK though. Tried both mic inputs, both transmit buttons and two different head sets. I do not see any rain dripping under the panel. I siliconed the outside and still get the same result. So I land and after about an hour they both work again. Any comments? I am thinking it is my old audio panel since it is on top and maybe getting a couple of drops on it. By the time I take out all those mooney screws to take a look there either was no water of it has all gone. Have had two different avionics guys look at it and they just covered up the top of the avionics and that did not work