[Elecraft] K2 frequency counter question

[Jim KO5V]

Thanks Don, that's good news. I'm not expecting perfection - just getting close will do for now. 

73, Jim  KO5V


-----Original Message-----
>From: Don Wilhelm <donwilh at embarqmail.com>
>Sent: Oct 29, 2018 2:53 PM
>To: Jim KO5V <ko5v at earthlink.net>, Elecraft List <elecraft at mailman.qth.net>
>Subject: Re: [Elecraft] K2 frequency counter question
>
>Jim,
>
>Of course that can be done.  You would need to construct a coaxial 
>counter probe similar to the internal probe (with a 10pF capacitor in 
>series with the tip), but unlike the internal probe, you would have to 
>provide a ground lead to the shield near the tip end. (the internal 
>probe depends on the K2 PC board ground for the return path - that does 
>not exist with an external device).
>
>The length of your "probe" coax may reduce the maximum frequency that 
>can be used.  With a short probe, the counter is good to 40 MHz.
>
>The K2 display is limited to 10 Hz resolution, and its accuracy is 
>dependent on properly setting the 4 MHz reference oscillator.  You can 
>check that by tuning to WWV in SSB mode and using the N6KR method to 
>determine the correct setting.
>The details of how to do that are on my website www.w3fpr.com K2 Dial 
>Calibration article.  The use of Spectrogram to determine that the 
>transmitted audio tones are received at the correct frequency.  If you 
>need Spectrogram, you can download it from my website opening page - 
>look near the bottom for the links.  I have versions 5.17 and version 16 
>there.
>
>73,
>Don W3FPR
>
>On 10/29/2018 2:53 PM, Jim KO5V wrote:
>> I have what may be a stupid or naive question: has anyone used the built-in frequency counter in a K2 to measure the frequency of a circuit external to the radio?
>> 
>> I found what may be a reference to this, done by a French ham, but his link no longer works. If this is possible, any info (especially potential gotchas) would be greatly appreciated. I have built a couple of nixie-tube clocks as Christmas gifts, and I need to adjust their internal frequency references. The output is a 400khz, TTL level square wave. I know I probably need more precision that the K2's counter may have, but right now, I just want to get as close as possible.
>>