[Elecraft] Problem: K2 Audio Tuning Click or Warble

[Bill Acito W1PA]

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