[Elecraft] Re: N6KR's 4 MHz oscillator cal method for the K2

[Don Wilhelm]

Folks,

I have also mentioned the option of zeroing WWV in CW mode.  See Ken's note
about the consideration for the sidetone pitch complication.

Ken is correct here - when using CW mode, you must also subtract your
sidetone pitch.

Suggestion - temporarily set the sidetone pitch to 500 Hz to make the
subtraction easier.

73,
Don W3FPR

----- Original Message ----- 
From: "Ken Wagner" <kewagner@ids.net>
To: "Wayne Burdick" <n6kr@elecraft.com>; "Vic Rosenthal" <vic@rakefet.com>
Cc: "Elecraft" <elecraft@mailman.qth.net>
Sent: Saturday, August 23, 2003 7:33 AM
Subject: Re: [Elecraft] Re: N6KR's 4 MHz oscillator cal method for the K2


| Good morning all:
|
| A few days ago someone reported that they followed this "new" procedure
and
| ended up 500-600 Hz off freq... I don't remember who, but it made me
| curious, 'cuz the math says it has to work.
|
| This morning I warmed up old #920 and tuned to WWV on 10 MHz on LSB. Using
| Spectrogram, I tuned to put the 600 Hz tone under the 600 Hz marker in
| S-gram, measured the VCO freq (14913.41) and the BFO freq (4913.42). This
| indicated ~10 Hz off.
|
| I then switched to CW mode, and zero-beat the carrier tone against the K2
| sidetone and got the following results... VCO = 14913.89; BFO = 4913.30.
The
| difference is ~590 Hz. Hmmm... that's the sidetone pitch I have set in. I
| checked with lowest pitch (400Hz) and highest pitch(800 Hz) and the
results
| track. So if one attempts to adjust C22 in CW mode so that the VCO - BFO
| exactly equals the display freq, then does the CAL PLL and CAL FIL, the
| result will be off by approximately the amount of the sidetone pitch. This
| makes sense because that is the way the K2 generated the CW offset during
| Rx.
|
| So to use CW mode for this method by zero beating the carrier against the
| sidetone, one must account for the sidetone pitch/CW offset that is set in
| the K2. The equation would be:
|         Tuned freq(10Mhz in this case) = VCO - sidetone pitch - BFO
|
| All with the usual caveat that one must make _sure_ that he is zero
beating
| the carrier freq and not the occasional 500 or 600 Hz tone from WWV.
|
| BTW... I didn't make any adjustments to C22 'cuz <= 10 Hz is OK for me.<g>
|
| 73, Ken K3IU
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
| ----- Original Message -----
| From: "Wayne Burdick" <n6kr@elecraft.com>
| To: "Vic Rosenthal" <vic@rakefet.com>
| Cc: "Elecraft" <elecraft@mailman.qth.net>
| Sent: Wednesday, August 20, 2003 22:36
| Subject: [Elecraft] Re: N6KR's 4 MHz oscillator cal method for the K2
|
|
| | This would work, Vic. I didn't mention it because historically we've
found
| that
| | many people have trouble listening for a beat-note. But this would make
a
| good
| | addition to the procedure.
| |
| | tnx
| | Wayne
| |
| |
| | Vic Rosenthal wrote:
| | >
| | > Wayne Burdick wrote:
| | >  > Use USB or LSB mode rather than CW, so that there will be no CW
| | >  > receive offset.
| | > ...
| | >  > TIP: Zero-beat the carrier precisely, or listen to a voice signal
and
| | >  > adjust the VFO for the best quality.
| | >
| | > Would it not be as good to use CW mode and tune for the slowest beat
| | > after holding SPOT?  I find this much easier than trying to find
| zero-beat.
| | >
| | > Or would this introduce some inaccuracy?
| | >
| | > Vic K2VCO
|
|
|