[Elecraft] K3 lost sensitivity

[Dave Hachadorian]

Late in the IARU Contest yesterday, I apparently got some RF into the front end of one of my K3's and blew something. Here are the symptoms:
1. The radio transmits just fine, with 100 watts output on the internal meter, and SWR appears normal.
2. I can hear signals, but they are much weaker than they should be on all bands.
3. Signals are equally weak whether I connect the antenna to ANT1, ANT2, or the BNC External ANT IN.
4. When I switch the K3's internal preamp and attenuator, the signals get louder and weaker, as they should, but always much weaker than normal.

I seem to remember someone having this problem before, but was unable to find the thread on the reflector. Was it something about a low-pass filter in the signal path?  I'll contact customer service tomorrow, but was hoping someone remembered the most likely cause today, so I wouldn't be stewing about it.  I really want to get the two radios going for the NAQP RTTY next weekend, so I hope it's field-repairable.

I'll start digging into the schematics now.

Thanks.

Dave Hachadorian, K6LL
Yuma, AZ