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

[andrew]

Hello Don
Thanks very much for the useful information.
I was able to source some trimcaps with the correct pin-spacing and a nominal range of 3 - 30pF.
The maximum values used bacame:
C21, C23, C32, C34 = 50pF
C44, C46 = 30pF
These resulted in all bands being easily tuned for peak output close to the middle of the trimming adjustment.
Thanks again.
Andrew
vk6wax

---- Don Wilhelm <w3fpr at embarqmail.com> wrote: 
> 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
> >
> >
>