[Elecraft] K1: C67 Interferes With Mounting KNB1

[Don Wilhelm]

Your "fix" for the too large C67 is likely OK.  I have not yet 
encountered that situation.

However, I offer a caution about the flux 'wash' you mentioned.  I trust 
you do not mean to flood the board with flux remover  I have attempted 
repairs on too many radios that have been "flux washed" improperly
In some cases, flux residue has been washed under the connectors and ICs 
and the only fix is to remove the components and further clean both the 
component and the board.  It makes one great mess and can result in a 
malfunctioning radio.  Even after such repairs, I 'cross my fingers' and 
hope the fault conditions do not reappear.

For what it is worth, HP does flux cleaning of production boards, but I 
understand from reliable sources that those boards that end up at rework 
stations are *not* to be cleaned of flux.  There must be a good reason 
for that procedural directive.

Solder flux is non-conductive - as long as no effort has been made to 
clean the flux.
The combination of flux and flux cleaners can leave conductive paths 
that will react later to moisture in the air and cause malfunctions.

If you *must* clean flux, do it in small areas at a time using the 
cleaner (denatured alcohol works) applied with a cotton swab (Q-tip) and 
cleaned up with a paper towel piece immediately - repeat until all the 
flux is gone.  Do not "wash" or "flood" the board or disaster may occur.

If you switch from solder with a Highly Reactive flux (Kester 44 for 
example) to a solder with a Mildly Reactive flux, no cleaning is 
nesessary (there is very little flux residue).  Kester 285 is one 
example and the Kester 'No Clean' is even better.  Save the Kester 44 
for work on antennas and old components which have substantial oxidation 
on the leads.

73,
Don W3FPR

On 3/21/2013 9:15 PM, Phil Barnes-Roberts WA6DZS wrote:
> Just finishing up a build for Tony, KE6JZF of a K1/KFL1-4/KAT1/KNB1
> (#3195), and have found that the 2.2uF-50V electrolytic cap C67 (where
> 25V is called out in the Parts List) may be a bit too tall.
>
> It doesn't seem to bother at C31, C54, or C10 on the NB board (all
> 50V).  When it came time to bolt the NB to the RF board, C67 was in the
> way.  After trying to gently re-wet the leads and lean it over U2, I
> wound up wrapping a little wire around the (too-short) leads and
> mounting it on its side under the board (which seems to fit OK.)
>
> Anybody seen a better fix for this physical interference fit?  Final
> flux wash is the next step, unless I hear better news.
>