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

[Dauer, Edward]

Don —

I have just had a back-and-forth with Elecraft Parts about the same 
question.

The K2 Manual, dated March 2012, lists for C44, C46, C32, and C34 trimmers 
p/n E540001, 5-30pF.  However, Revision I-3 dated September 1, 2015, lists 
for C32 and C34 p/n E540002, 10-50 pF; and for C44 and C46, p/n E540001, 
5-30 pF.  What I received in a kit ordered on Sept. 7 was apparently what 
the I-3 Revision called for - there were two white ceramic and two bright 
red plastic trimmers, with no markings on either to say which was which.  
When I inquired, Parts told me (two days ago) that the red plastic 
trimmers were p/n E540001, and that (here’s the quote), "we'll send the 4 
E540002 trimmers. The E540001 trimmers are obsolete and you can use the 
E540002 trimmers in place of them.”

Taking this together with your note leaves me wondering . . . Help?

As an aside, the C21 and C23 values are listed in both the Manual and the 
Revision as p/n 540000, 8-50 pF.

Ted, KN1CBR
 


>Message: 29
>Date: Fri, 2 Oct 2015 08:28:07 -0400
>From: Don Wilhelm <w3fpr at embarqmail.com>
>To: andrew <andw at bigpond.com>, elecraft at mailman.qth.net
>Subject: Re: [Elecraft] [K2] Band-Pass Filter Trimcap values
>Message-ID: <560E7857.1080807 at embarqmail.com>
>Content-Type: text/plain; charset=windows-1252; format=flowed
>
>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
>>
>****************************************