[Elecraft] K3 - speaker buzz

[Jim Wiley]

I don't have a K3 (yet) but I have had some luck with similar problems 
in other equipment by inserting a small (typically about 1" to 2" [25 to 
50 mm] ) square patch of felt between the vibrating panel (the top cover 
in this case) and some  internal part, such as a shield box or 
partition, that was "close".    Sometimes it has been necessary to fold 
the felt once or twice to get it to wedge in place.   The felt provides 
a "dampener" to kill the resonances that cause the problem.   You may 
find that moving the felt to different positions is needed to find a 
"sweet spot".   


A dab of rubber cement serves well to hold the dampener in place, but be 
careful --  the solvents in rubber cement can sometimes damage the 
finish of painted surfaces.    In these cases, some double-sided 
"Scotch" tape will do the trick. 


I have also seen the thick tape with a foam core between two outer 
surfaces used to do this same job, but I am thinking that felt works 
better.  The tape material can be found in places like building supply 
stores or craft shops, and is used for mounting  pictures on walls and 
similar applications.


- Jim,  KL7CC
 

Nick-WA5BDU wrote:
> 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
>