[Elecraft] K3 3051 audio buzz in chassis on SSB

[Craig]

Hi Paul

I had a similar problem which drove me nuts.

I pulled the K3 apart to try and find this problem and  tightening every screw in the 
re-assembly process. The  problem persisted however. This  buzz was following my SSB 
modulation  with perfect timing.

I used a stethoscope and found that the buzz was  coming from a small area where the
SWR/power meter directional coupler was situated. The problem turned out to be one of 
the directional couplers transformers which was arcing to the ferrite core. 

At first sight the transformer looked perfect, however I could clearly hear the buzz in the 
stethoscope. I replaced the ferrite transformer and the buzz went away. When I examined  
this   transformer,  the arcing signs were very obvious under the enamel wire facing the 
core.

The directional coupler transformers are very small and its a tricky job getting it  back in 
place. Ideally this transformer should have better insulation, however there is not much 
room on the  core for extra insulation. 


73
Craig