Hi David!
For fine tune C22 you can use the simplest method with PC and specrpogram.
There is the original UA6HJQ's method:
-connect K2's AF-out to PC mic-input, and phones to PC phone out;
-turn On K2 and PC, and wait for 50-60 minutes (for temperature stability);
-check the connection "TP1=>Control Board";
-run the Spectrogram, and set for it: Scale -60db, FFT 8192, Band 640 -
1329Hz
and set marker to 1000Hz;
-set LSB-mode, and tune VFO at 10001,00kHz (WWV), if ANT is connected
you have to hear WWV-signals in headphones,
-if we see the WWV-signal peaked on 1000Hz (our marker on Spectrogram),
it's the ideal point for C22.
-if not, turn VFO for peaking the WWV-signal at 1000Hz-marker.
-f.e. if we have 10001,20kHz we'll have to subtract 20 (in later steps),
if we have 10000,80 we'll have to add 20 (in later steps)
- MENU => CAL => CAL FCTR (don't touch VFO-knob!)
- we can see 14914,70 (for example)
- now if we had 10001,20 we must to subtract: 14914,70-20=14914,50
(if we had 10000,80 => 14914,70+20=14914,90)
-now slowly turn C22 for 14914,50 readings (or 14914,90)
-recall CAL PLL for TP1 on 40m band
-recall CAL FIL for TP2 on each filter/mode.
Now you can recheck your K2 on WWV at 10001,00 kHz, as a rule the error
makes
few Hz.
Same pictures you can see if follow here (in russian):
http://www.hamradio.cmw.ru/elecraft/calibrated.htm
73! Alex
K2#5287
On Mon, 15 Oct 2007 15:44:31 +0300, Don Wilhelm <[EMAIL PROTECTED]>
wrote:
David,
The same principles work fine for any known frequency, it is just that
the subtraction of the BFO frequency from the VFO frequency is not as
straightforward.
An AM station broadcasting standard and constant tones (such as WWV) is
easiest because one can observe the demodulated audio tones with
Spectrogram assuring accurate tuning. If you have a good ear, you may
be able to tune to a station broadcasting music to within 5 or 10 Hz.
If you do use an AM broadcast station without standard tones as your
standard, I would suggest that you tune it by ear in LSB or USB first,
then switch to CW while observing the audio with Spectrogram - the
carrier should appear 'straight and tall' at the frequency you have set
in the K2 for the sidetone pitch - thus assuring accurate tuning of the
station. Then go back to SSB mode to set C22 while doing the
subtraction between the VFO and BFO frequencies. A note to help - any
adjustment of C22 will move the VFO frequency reading about 5 times
faster than the BFO reading, so do the adjustment with the counter probe
plugged into TP1 and then check the result in TP2. A few trials should
yield an accurate setting.
73,
Don W3FPR
David Woolley wrote:
Don Wilhelm wrote:
refer to the K2 Dial Calibration article on my website
http://w3fpr.qrpradio.com for techniques to accurately set the 4 MHz
reference oscillator and the following steps to achieve good dial
calibration.
Unfortunately, the sun doesn't seem to favour picking up WWV. The
original calibration was against the MHz birdies on an FRG7, which was,
I think, calibrated against WWV in the past. However I just tried on
some 41m broadcast stations, and it looks like the calibration might be
30 to 40 Hz high on that band, which probably equates to 50 to 70 Hz,
in the same sense, on 10m, so I may try a calibration against those
broadcast stations. (Does anyone know a relatively accurate broadcast
station, receivable in a noisy location in the UK, and near the high
end of the VFO range?)
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