K2 #5613 BFO low freq problem

[Rajiv Dewan, N2RD]

I am building K2 #5613 and having a great time.  I am doing Alignment
and Test Part II.

My problem is the following:
  BFO High Freq 4,916.98 KHz and it is greater than 4916.3 as it should be.
  BFO Low Freq 4,912.92 KHz, this is higher than what it should be
(4,912.7).
  Although the range is OK (4.06Khz is the range I get, which is greater
than the minimum 3.6KHz) , the lower freq seems a little off.

As background, I calibrated the frequency (C22) quite accurately using
my HP5342 counter slaved to a HP GPS 10Mhz reference.  All other prior
tests were just fine.

What should I do about BFO Low Freq being higher than it should be?

Suggestions welcome.
Raj, N2RD


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[John, KI6WX]

Add a small capacitor in parallel with C173.  I would imagine 10-20pF would
drop the low frequency down into the desired range.
-John
 KI6WX
>
> My problem is the following:
>  BFO High Freq 4,916.98 KHz and it is greater than 4916.3 as it should be.
>  BFO Low Freq 4,912.92 KHz, this is higher than what it should be
> (4,912.7).
>  Although the range is OK (4.06Khz is the range I get, which is greater
> than the minimum 3.6KHz) , the lower freq seems a little off.
>

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[Rajiv Dewan, N2RD]

As suggested in the note, I added 2pf NP0 from my junkbox from X3 / X4
junction (where it connects to L33) to ground.  This fixed the problem.  
With this mod:
BFO High 4917.00
BFO Low  4912.48
Range               4.52
They all seem fine.
Thanks for you help,
Raj, N2RD

Leigh L. Klotz, Jr. wrote:

> Rajiv,
> You might want to send mail to [hidden email] for your case, but
> here's the advice I got.
> Note that mine was #3121 your advice from Elecraft may be different:
> http://www.ac6rm.net/mailarchive/html/elecraft-list/2005-08/msg00562.html
>
> 73,
> Leigh/WA5ZNU
>
> Rajiv Dewan, N2RD wrote:
>
>> I am building K2 #5613 and having a great time.  I am doing Alignment
>> and Test Part II.
>> My problem is the following:
>>  BFO High Freq 4,916.98 KHz and it is greater than 4916.3 as it
>> should be.
>>  BFO Low Freq 4,912.92 KHz, this is higher than what it should be
>> (4,912.7).
>>  Although the range is OK (4.06Khz is the range I get, which is
>> greater than the minimum 3.6KHz) , the lower freq seems a little off.
>>
>> As background, I calibrated the frequency (C22) quite accurately
>> using my HP5342 counter slaved to a HP GPS 10Mhz reference.  All
>> other prior tests were just fine.
>>
>> What should I do about BFO Low Freq being higher than it should be?
>>
>> Suggestions welcome.
>> Raj, N2RD
>>
>>
>> _______________________________________________
>> Elecraft mailing list
>> Post to: [hidden email]
>> You must be a subscriber to post to the list.
>> Subscriber Info (Addr. Change, sub, unsub etc.):
>> http://mailman.qth.net/mailman/listinfo/elecraft   Help:
>> http://mailman.qth.net/subscribers.htm
>> Elecraft web page: http://www.elecraft.com
>
>