[Elecraft] [k2] Poor USB audio after cal

[Don Wilhelm]

Damon,

Well, I certainly hope your flux cleaning efforts have not created 
problems.  It often does create leakage paths that can cause problems.  
Solder flux by itself is non-conductive, and is best left alone - but 
when combined with many flux cleaning ?solvents?, conductive paths can 
be created that will cause insurmountable problems.  I have seen 
attempts at removing flux which resulted in complete failure for the 
kit.  Conductive paths can be created under connectors, under ICs and 
any other component.

If you want to be safe, *do* *not* attempt to remove solder flux.  If it 
gets really nasty in one area after several re-work attempts, you can 
remove the excess flux from that area with alcohol applied sparingly 
with a Q-tip and dried immediately.

Use of a solder with a mildly reactive flux will leave almost no flux 
residue - Kester 285 is one of that type.  Kester no-clean solder is 
another that works well.  Save the Kester 44 with its Highly Reactive 
flux for antenna projects and wires that have developed some oxidation 
over time - it leaves a lot of flux residue, but cleans nicely - that 
kind of cleaning is not necessary on new boards and new components.

Yes, I know that Elecraft "recommends" Kester 44 (among others), but 
only because it is OK to use (provided you do not try to remove the flux 
residue).  IMHO, it is not the best choice for new construction.

73,
Don W3FPR

On 7/24/2011 10:14 PM, KC5CQW wrote:
> TNX for the info.
> I'll go over your method in detail tomorrow.
> I have a hunch it may be due to the R1 SSB balancing pot.
> Dummy me forgot to mention that I disassembled the k2 a few months ago to
> clean all of the old flux off.
> Perhaps the pot has some residue or wasn't setup right to begin with...
>
> Now that the K2 has settled in, I may go and do a 100% verification on all
> adjustable points for max efficiency. (My 12m/10m output is much lower then
> expected. 4-5W max).
>
> 73, Damon
>
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