[Elecraft] K2 BFO

[jerry]

Hi Don,

    One of the first things I did after getting this rig in the mail, was 
to verify that it received WWV at the proper frequency - and that USB 
sounded like LSB.  That reassured me
that the dial was accurate enough to keep me inside the ham bands.

    People often instruct one to "zero beat" WWV.  I fail to see how this 
can be done with an SSB receiver with a properly set BFO, since the 
carrier is then outside of the filter bandpass.   Also, except during 
the announcement period, WWV is actually transmitting multiple "carrier" 
frequencies at the same time.

    Not going to mess with SSB a lot at this time because I have the SSB 
adapter on order, and I'd have to do it all again anyway after receiving 
that.

    I just calibrated the counter with the GPSDO.  It was showing 
9.....96 ( forget how many digits :).  A quick tweak of the trimmer cap 
got it to 10.0000 ( however many zeros ).

    This is just a temporary bodge, because I also have a TCXO on order, 
will have to do that again too.

                      - Jerry KF6VB






On 2021-06-28 10:39, Don Wilhelm wrote:
> Jerry,
> 
> That GPSDO will be good for setting the dial calibration, but WWV is
> better since it transmits AM at a fixed frequency.
> Instructions for doing a good dial calibration are on my website
> www.w3fpr.com.  It explains the entire procedure.
> Use SSB when doing the dial calibration because there is an offset if
> you try to use CW - no offset with SSB.
> 
> 73,
> Don W3FPR
> 
> On 6/28/2021 1:05 PM, jerry wrote:
>> 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
>> 
>>