[Elecraft] Problem: K2 Audio Tuning Click or Warble

[w6fvi]

Sounds to me like that pretty fragile RFC15 (E690013) has opened. Scott 
(parts at elecraft.com) can get you a new one right away.

Brian, W6FVI

Bill Acito W1PA wrote:

> Update.
>
> 1. Tom (N0SS) suggested I redo the CAL PLL. Done. No effect.
>
> 2. Jim (K4ZM) suggested I....
>
>> Check the resistance of the small 100uh rfc that you added between 16 
>> and the +12 volt line.  I have seen this same problem when that RCF 
>> is open. It is a very delicate choke and very easy to break the wire 
>> inside the choke. An easy way to test it is to measure the dc voltage 
>> on both sides of the rfc and if the voltage is not the same then you 
>> probably have a bad RFC.
>
>
> ..so I popped the bottom and took a look. On the rail (which is not 
> 12v, btw), I read 5.02V,
> and on the other side of the 100uH I read 4.23V...  not the "same", 
> but I assume that's the
> choke wire resistance. Along the same vein, I also remembered that 
> someone else attributed
> this issue to the added LC circuit (as part of the A-B version update):
>
> http://www.ac6rm.net/mailarchive/html/elecraft-list/2003-08/msg00424.html
>
> So I took the blade of my screwdriver and shorted the 100uH inductor 
> (RFC15)....  warble is gone!
>
> So, questions:
>
> Are the L-C comps "hard-linked"? i.e. if I remove this mod, is there 
> any benefit to leaving the cap,
> or should I remove both parts? Should I try a different 100uH instead? 
> I don't think I ever had the
> 7128 warble, so I installed these as a precaution only.
>
> Any ideas on why this LC circuit is the culprit (might want to look at 
> this since there is at least two confirmed cases now)?
>
> As Wayne suggested in the included link, I also checked the value of 
> R19 and it was fine.
>
> Bill
> W1PA
>
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