[Elecraft] [K2] Band-Pass Filter Trimcap values

[Don Wilhelm]

Andrew,

C21 and C23 are good with the ceramic capacitors with the red dot - use 
those supplied with your kit.
C32 and C34 need approximately 25 pF to tune, and your current brown 
trimmers should do the job nicely.
For C44 and C46 the capacity needed is approximately 10 pF (the brown 
body trimmers will *not* work).
The trimmers currently being supplied for use at C44 and C46 are PN 
E540011 and have a red body.

If you ordered your K2 in the last quarter of 2014 the kit was supplied 
with 4 brown bodied trimmer capacitors (that was corrected in 
December),  which were supposed to have a minimum capacity of 6pF but 
the actual minimum capacity is more like 20pF.  I don't know if the 
manufacturer had an incorrect value on the data sheet, or what happened, 
but the actual range of those brown trimmers is nominally 20 to 60pF.

So bottom line, the brown trimmers will work fine at C32 and C34 and are 
what is currently being supplied in new kits.
The trimmers now being used for C44 and C46 are PN E540011 and have a 
red body.  You can request those from parts (at) elecraft.com.

If you want to procure trimmers locally, and you can fine 5-30pF 
trimmers, they will work, but watch the minimum capacitance of anything 
you substitute, particularly for C44 and C46.

73,
Don W3FPR


On 10/2/2015 6:04 AM, andrew wrote:
> During initial build I didn't have a signal generator and wasn't happy with the band-pass filter alignment for the 12m and 17m bands which use trimcaps.
> Revisiting the alignment with a newly acquired signal generator I found I couldn't get a correct adjustment and removed C46 - it's maximum value is 66pF when it should be approx 30pF.
> I removed C32, C34 and C44 and all have a max of approx 66pF. I  also checked C21 and C23 which are correct with a maximum of 50pF. (and different physical construction with Red mark)
> Before I make replacements I would like to confirm that the correct values should be:
>
> C21, C23 = max 50pF
> C32, C34, C44, C46 = max 30pF
>
>