[Elecraft] K2 BFO

[jerry]

All,

    OK, I did it.  Made up a counter probe from a hunk of
rg316, crimped a couple of dupont female clips onto the end,
put them in a shell, squished a dab of hot melt glue between the pins so 
they couldn't short out, slipped over a bit of shrink...etc.

   I recently acquired a GPSDO ( GPS Disciplined Oscillator ) that is 
supposed to emit 10MHz accurate to a tiny fraction of a Hertz.  Will be 
using that to calibrate the frequency counter.  But for the nonce...

... I redid all 8 CW BFO settings - first wrote down what they were - by 
holding a tablet up to the K2 and running spectrum analyzer software I 
got off Google Play.  I centered each passband at about 600Hz.

   The rig is transformed. Now all of the selectivity settings are 
completely usable.  Wish it had been like this yesterday.  And I wish 
there were more signals to listen to today :).

                      - Jerry KF6VB


On 2021-06-28 08:14, Don Wilhelm wrote:
> Jerry,
> 
> Yes, you need to have the counter probe plugged into TP2 to save thee
> BFO frequency.
> You can build your own probe - if you use #14 solid wire, it will fit
> nicely into the test points.
> Solder the 11pF right above the tip and coax up to the header on the
> Control Board - the shield goes closest to the left side panel.
> 
> 73,
> Don W3FPR
> 
> On 6/28/2021 11:00 AM, jerry wrote:
>> Hello all,
>> 
>>    I note that my new ( to me ) K2 is not well set up on the BFO for 
>> the narrow CW filters.  It's fine for the 1.5kHz one, but the audio 
>> passband is too high for all the narrower ones - so I cannot "spot" 
>> tune.   If my sidetone is set to say 600Hz,
>> it's on the lower slope of the audio peak.
>> 
>>   It seems to be straightforward to adjust the BFO per filter with the 
>> CAL FIL function.  With a tablet running a spectrum analyzer, I can 
>> pull the audio spectrum right down to where it needs to be, no 
>> problem.
>> 
>>   HOWEVER, when I try to save it, I get "INFO 230" which means that 
>> the frequency counter is not connected to the BFO.  And the passband 
>> doesn't stay changed.
>> 
>>   Is it true that the rig will refuse to save the BFO setting unless 
>> it can measure the BFO frequency?
>> 
>>    My radio came to me without a frequency probe.  I do have one on 
>> order from Elecraft.  I also have enough junk to make one.  A hunk of 
>> RG316, some dupont connectors, an 11pf dipped silver mica capacitor.
>> 
>>   But - at the moment, I really don't want to do any of that stuff.  I 
>> just want to slide the audio output spectrum down to where I can get 
>> on with operating.  And I'm not interested in the numerical BFO 
>> reading.  Ultimately, I will set up the filters from scratch - I have 
>> the upgraded crystals AND the SSB adapter on order.
>> 
>>  Can the radio REALLY not save the BFO setting unless it can measure 
>> it?
>> 
>>                      - Jerry KF6VB