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

[andrew]

Hello Ted

>From your callsign I'm assuming your are in the USA, in which case I would recommend sourcing any required parts direct from Elecraft. I'm in VK-land so it was expedient to source locally.

The values I had success with are noted below, which tallies with the advice from Don and the updated errata I-3.

Best wishes with your K2 build.
Andrew
vk6wax

---- "Dauer wrote: 
> Andrew —
> 
> What is the source?  I am still wrestling with this problem.
> 
> Tnx,
> 
> Ted, KN1CBR

---- andrew <andw at bigpond.com> wrote: 
> 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
> > >
> > >
> >