K2 Clean or replace AF Gain control?

[Tom KG3V]

I just noticed my K2 has a problem with the AF Gain control. It  
is "scratchy" in the area where I use it most. I see that the RIT control  
(rarely used) also has some linearity issues. The rig is about three years  
old. I do not use it on a daily basis, but I do use it in contests , where  
it gets stressed pretty well.

I must either clean or replace the AF Gain control ASAP, and I see it will  
be rather hard to get at. Can anyone tell me if these controls can be  
accessed to clean them, or should I just order replacement parts? It would  
help to know before I tear the rig apart.

Thanks and 73,

Tom, KG3V
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[ke9uw]

Does this app note apply here?

Application Note: Alternative Wiring for the K2's AF GAIN Control
Wayne Burdick, N6KR, with illustrations by Tom Hammond, N0SS      
Oct. 25, 2001
This optional modification greatly reduces the level of noise or other artifacts that might be heard on a small number of K2s when rotating the AF GAIN potentiometer. Pots judged as "noisy" are, in fact, probably good; the original circuit is simply sensitive to the pots' inherent non-linearities. In addition to eliminating most pot noise, the new circuit provides nearly dead silence when the control is fully CCW, while the old circuit allowed a small amount of leak-through.

You can find the whole note in K2/K1 applications.

---- Original message ----

>Date: Tue, 10 Nov 2009 02:35:10 +0000
>From: [hidden email]  
>Subject: [Elecraft] K2  Clean or replace AF Gain control?  
>To: [hidden email]
>
>I just noticed my K2 has a problem with the AF Gain control. It  
>is "scratchy" in the area where I use it most. I see that the RIT control  
>(rarely used) also has some linearity issues. The rig is about three years  
>old. I do not use it on a daily basis, but I do use it in contests , where  
>it gets stressed pretty well.
>
>I must either clean or replace the AF Gain control ASAP, and I see it will  
>be rather hard to get at. Can anyone tell me if these controls can be  
>accessed to clean them, or should I just order replacement parts? It would  
>help to know before I tear the rig apart.
>
>Thanks and 73,
>
>Tom, KG3V
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html

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[Don Wilhelm-4]

Tom,

If the K2 SN is below SN 3000, then I would suggest the Alternate AF
Gain wiring mod be done.  If the pot still is noisy, then replace the pot.
For SN above 3000, just replace the pot.  The use of cleaners is "iffy"
IMHO - if the pot is worn, no cleaner in the world will help it on a
permanent basis - any improvement will be short lived.  Besides, it is
difficult to ge any cleaner inside the pots used in the K2.

73,
Don W3FPR

[hidden email] wrote:

> I just noticed my K2 has a problem with the AF Gain control. It  
> is "scratchy" in the area where I use it most. I see that the RIT control  
> (rarely used) also has some linearity issues. The rig is about three years  
> old. I do not use it on a daily basis, but I do use it in contests , where  
> it gets stressed pretty well.
>
> I must either clean or replace the AF Gain control ASAP, and I see it will  
> be rather hard to get at. Can anyone tell me if these controls can be  
> accessed to clean them, or should I just order replacement parts? It would  
> help to know before I tear the rig apart.
>
> Thanks and 73,
>
> Tom, KG3V
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.698 / Virus Database: 270.14.56/2491 - Release Date: 11/09/09 02:39:00
>
>  

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[AC7AC]

CONTENTS DELETED

The author has deleted this message.

[Don Wilhelm-4]

Tom,

The "Alternate AF Gain Wiring" change is present on the board wiring of
all K2s with a SN greater than 3000.

73,
Don W3FPR

[hidden email] wrote:

> Don,
>
> Mine is SN 5848 (I think), so does that mean the "alternate wiring
> mod" does not apply? I am sure this pot was not like this from the
> original build. I also suspected that it may be pointless to try and
> clean it. I will replace the two.
>
> If this is something that will happen after a couple years, maybe I
> should buy a few of them (or look for a higher quality/cost
> replacement part).
>
> Thanks and 73,
>
> Tom, KG3V
>
>
> On Nov 10, 2009 3:27am, Don Wilhelm <[hidden email]> wrote:
> > Tom,
> >
> >
> >
> > If the K2 SN is below SN 3000, then I would suggest the Alternate AF
> Gain wiring mod be done.  If the pot still is noisy, then replace the pot.
> >
> > For SN above 3000, just replace the pot.  The use of cleaners is
> "iffy" IMHO - if the pot is worn, no cleaner in the world will help it
> on a permanent basis - any improvement will be short lived.  Besides,
> it is difficult to ge any cleaner inside the pots used in the K2.
> >
> >
> >
> > 73,
> >
> > Don W3FPR
> >
> >
> >
> > [hidden email] wrote:
> >
> >
> > I just noticed my K2 has a problem with the AF Gain control. It  is
> "scratchy" in the area where I use it most. I see that the RIT control
>  (rarely used) also has some linearity issues. The rig is about three
> years  old. I do not use it on a daily basis, but I do use it in
> contests , where  it gets stressed pretty well.
> >
> >
> >
> > I must either clean or replace the AF Gain control ASAP, and I see
> it will  be rather hard to get at. Can anyone tell me if these
> controls can be  accessed to clean them, or should I just order
> replacement parts? It would  help to know before I tear the rig apart.
> >
> >
> >
> > Thanks and 73,
> >
> >
> >
> > Tom, KG3V
> >
> > ______________________________________________________________
> >
> > Elecraft mailing list
> >
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> >
> > Help: http://mailman.qth.net/mmfaq.htm
> >
> > Post: mailto:[hidden email]
> >
> >
> >
> > This list hosted by: http://www.qsl.net
> >
> > Please help support this email list: http://www.qsl.net/donate.html
> >
> > ------------------------------------------------------------------------
> >
> >
> >
> >
> >
> > No virus found in this incoming message.
> >
> > Checked by AVG - www.avg.com Version: 9.0.698 / Virus Database:
> 270.14.56/2491 - Release Date: 11/09/09 02:39:00
> >
> >
> >
> >  
> >
> >
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.698 / Virus Database: 270.14.56/2491 - Release Date: 11/09/09 02:39:00
>
>  

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[Julian, G4ILO]

Perhaps because it was many years before i got round to doing the wiring modification, my K2 volume control remained scratchy even after I did the modification. It's only noticeable when turning the control, though, so I decided I would live with it rather than attempt a replacement.