[Elecraft] K2 12m alignment

[Don Wilhelm]

Harry,

The yellow ones do not go reliably down to 6.8pF, many are limited to a 
minimum capacity of about 15pF.

The capacity for the 12 meter bandpass needs to be in the 11 to 12pF 
range or less.

Yes, I have measured several of them.  I went through this as the tester 
for Elecraft when the wide range blue trimmers were no longer available.

The current ceramic trimmers (white with red dot) do not reliably go 
down to 5pF - the minimum is more like 12 to 15.  The old blue trimmer 
capacitors had a reliable range of 5 to 40pF and were ideal, but alas, 
they are not longer available.

This thing with trimmer capacitors is turning into a 'bag of worms'.

73,
Don W3FPR

On 2/26/2017 7:50 PM, Harry Yingst wrote:
>
> I would think it would be best to use:
>
> The Yellow (ones 6.8-45pf) at  C44 & C46 (10/12 m) since the schematic 
> calls for 5-30pf
>
> The White with Red dot ceramic trimmers (8-50 pf) at C19 and C23 
> (20/30m) since the schematic calls for a 50pf trimmer
>
> C32 and C34 should also be 5-30 as per the schematic, so a better 
> substitute would seem to be to use the Yellow 6.8-45 pf trimmers
>
>
>
>
>
>
>
> ------------------------------------------------------------------------
> *From:* Chuck Stover via Elecraft <elecraft at mailman.qth.net>
> *To:* "donwilh at embarqmail.com" <donwilh at embarqmail.com>; Robert Kasten 
> <bkasten at octavian.net>; "elecraft at mailman.qth.net" 
> <elecraft at mailman.qth.net>
> *Sent:* Sunday, February 26, 2017 6:52 PM
> *Subject:* Re: [Elecraft] K2 12m alignment
>
> Bob, Don,
> I just finished up a K2 as well.  The trimmers I got didn't match the 
> description in either the manual or errata, so I wasn't sure what I 
> was looking at.
> I had to use clip leads from my cap meter and got too much stray stuff 
> going on to accurately measure min and max.
> I talked to Gary in Watsonville.  Here's what we summized.  The larger 
> bodied yellow trimmers went into c21 and c23.  The remaining 4 smaller 
> bodied white with red band trimmers went into c32, c34, c44 and c46.
> It works.  I get good output on all bands.
> Don't know if this helps or not.
> Chuck K4QS
>
>
>       From: Don Wilhelm <donwilh at embarqmail.com 
> <mailto:donwilh at embarqmail.com>>
> To: Robert Kasten <bkasten at octavian.net 
> <mailto:bkasten at octavian.net>>; elecraft at mailman.qth.net 
> <mailto:elecraft at mailman.qth.net>
> Sent: Sunday, February 26, 2017 6:10 PM
> Subject: Re: [Elecraft] K2 12m alignment
>
> Bob,
>
> You have too much capacitance at C32 and C34.
>
> Contact Elecraft support and ask them to send 2 trimmer caps to replace
> C44 and C46.  The ones you have with your kit do not have a small enough
> minimum capacitance.  The p/n you need is E540011 and the bodies were
> red the last time I saw them.
>
> The 35 to 70pF range you measured is higher than I would expect.  They
> should measure about 20pF to 45pF.
>
> If you have a similar problem with the maximum power on 18 MHz as well,
> ask for replacements for C32 and C34.  The part number is E540002 and
> they have yellow bodies.
>
> See the latest Errata page - download it from the Elecraft website.
> Trimmer capacitors have become a problem for Elecraft over the past 6
> months or so.  I believe you have brown body trimmers at C32, C34, C44
> and C46.  Several of those were found not to meet the manufacturer's
> specs for capacitance range and were dropped.
>
> 73,
> Don W3FPR
>
> On 2/26/2017 5:41 PM, Robert Kasten wrote:
> > Finished my K2 in the last few days and really enjoyed the build. It was
> > just like old times.
> >
> > All bands except 12m have aligned OK...but I cannot get any more 
> than .5W
> > output on 12m - no matter the C44/46 trimmer cap settings or the power
> > setting. And while it not fun, I pulled components 
> C42,C43,C44,C45,C46,C47
> > and C48 and they all showed fine on the cap tester. C32 and C34 are
> > adjustable from about 35pf to 70pf.
> >
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