[Elecraft] K3 - speaker buzz

[Nick-WA5BDU]

A month or so ago there was a flurry of posts about buzz in the 
speaker.  On poster replaced fiber washers used to mount the speakers 
with neoprene and reported good results.

With my sidetone level set at about 45, I heard pronounced buzzing at 
350 and 400 Hz sidetones.  (Adjust your sidetone level with MON, then go 
to PITCH and adjust the sidetone pitch throughout its range.)

Since I had to pop the top to install my back ordered 6kHz filter, I 
took the opportunity to replace the fiber washers with improvised ones 
made from small grommets sliced in half.  I did get some improvement.  
Now the major buzz is limited to 350 Hz.  In putting some slight finger 
pressure at various places on the top cover, I see that the speaker 
isn't at fault but that the top plate has some resonances.  I'm thinking 
of putting some kind of resonance killers on the underside, maybe some 
globs or beads of RTV or similar, so as to avoid any kind of permanent 
change to the rig.

Anyone else done anything similar?

73--Nick, WA5BDU
#1195