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K3 - speaker buzz

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Nick Kennedy

K3 - speaker buzz

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

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Jim Wiley-2

Re: K3 - speaker buzz

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
>

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Steef PA2A

Re: K3 - speaker buzz

In reply to this post by Nick Kennedy

I am still using the original washers, but I have put two nuts on each of
the four screws to prevent the nuts from falling into the rig.

Steef PA2A
K3 #1184

----- Original Message -----
From: "Nick-WA5BDU" <[hidden email]>
To: <[hidden email]>
Sent: Friday, August 01, 2008 8:26 PM
Subject: [Elecraft] K3 - speaker buzz

>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
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

Paul-285

Re: K3 - speaker buzz

In reply to this post by Nick Kennedy

>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.

Car stereo installers use a thin but heavy black mat with adhesive on
one side to dampen resonances in door panels.
It's also used on the inside walls of computer cases to dampen fan noise.
A few of their throw-away scraps stuck on the inside of the cover
would probably fix you right up.

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