[Elecraft] K2 dial alignment

[paul]

Hi Don,

You are right that I interchanged TP1 and TP3 in my post but the 
information was correct otherwise.  While the orginal post did have a 
difference of 9999.86 Khz instead of 10MHz, I have rerun the procedure 
with an exact difference of 10MHz (by small adjustments in C22).  

Last run:

TP1: 14913.28
TP2:  4913.28

When running CAL FIL (on 7MHz), I have changed the BFO frequency by 1 or 
2 count and left it changed (to make sure).  This was done on every mode and 
xtal setting.  

On a prior run, I also tried varying the bandwidth setting of each mode 
and xtal - also no difference at all.  Also tried to run CAL PLL on 10MHz 
- results in error code.  Same error code with CAL FIL on 10MHz.

All bands are off by at least 10khz.

7mhz reads +10khz
10mhz reads +12khz
14mhz reads +20khz

Just for grins, I have tried transmitting at 10Mhz (dial 10.012) into a 
dummy load.  SWL receiver hears it on 10MHz zero beating with WWV.  I 
have run spectragram software to adjust the filters and have checked the 
filters by ear.  It seems to work well - no weirdness.  I have checked to 
make sure the filter is on the correct side of the bandpass (7MHz) - 
lower side for LSB,CW and high side for USB and /CW.

When listening to 10MHz WWV (dial 10.012MHZ), I can switch between USB and 
LSB and the voice is perfectly tuned in on both settings.

Current MCU firmware is 2.02.  Have the MCU 2.04 firmware, but not the 
current IOC version.  Now eagerly waiting for it! :)

Maybe I have done something stupid - just stumped for now.

Thanks for your help.

Paul
AD5IW

On Mon, 3 Dec 2007, Don Wilhelm wrote:

> Paul,
> 
> Your original post had the BFO at 4913.19 kHz and the VFO at 14913.05
> when receiving 10 MHz WWV.  Clearly the difference is not 10 MHz, and
> that indicates that C22 was not properly adjusted.
> 
> Briefly, the procedure is:
> NOTE: The K2 must be in LSB or USB mode - not CW.
> 1) Tune WWV precisely (ignoring the dial reading)
> 2) Adjust C22 until the BFO and VFO are different by the frequency of WWV
> (10 MHz for 10 MHz WWV - the low order digits should match exactly.
> 3) Switch to 40 meters and run CAL PLL
> 4) CHANGE each BFO setting to force the K2 to record new DAC values in
> EEPROM.
> 5) Check the results by tuning WWV again - the dial reading should be
> correct.
> 
> You said you were following that procedure, but somewhere along the line
> something has apparently gone wrong - the order of things is important
> for this procedure to work properly.  It works every time for me, and I
> use it frequently.
> 
> Have you interchanged TP1 and TP3? - they were incorrectly labeled in
> your original post.  The frequency difference is observed between TP1 and
> TP2 - TP1 is located near T5 and TP2 is located below the KSB2 board
> location (through access hole when the KSB2 is installed).  TP3 is near
> the front and is not used in this procedure - it is the PLL frequency and
> will always be in the range of 12 MHz.
> I suggest you simply try again.
> 
> 73,
> Don W3FPR
> 
> paul wrote:
> 
>  Hi Don,
> 
> I have read your website (and 50+ posts) and done this procedure about 5 
> times over the last 3 days - each time with the same result (no change).
> 
> Followed a procedure that made the two frequencies (TP3 and TP2) 
> exactly 10MHz apart by varying C22.  Ran CAL PLL (7.1 Mhz) and then ran 
> CAL FIL.  Made small changes to each BFO frequency on all modes 
> (USB,LSB,CW,/CW) and Xtal selections.  No change at all - WWV is still at 
> 10.012 MHz.  WWV voice is perfectly tuned in both USB and LSB.
> 
> Right now the radio works great except for this problem.  Guess I will try
> again when I get the new firmware.
> 
> Thanks for your help,
> 
> Paul
> AD5IW
> 
> On Mon, 3 Dec 2007, Don Wilhelm wrote:
> 
>   
> 
>  Paul,
> 
> The exact frequency of the 4 MHz (nominal) reference oscillator may be
> slightly different than exactly 4 MHz. 
> If you have a well calibrated external frequency counter, you can adjust the 4
> MHz reference (adjust C22) by measuring the frequency at TP1 with both the
> internal counter and the external counter - adjust C22 until the internal
> counter reads the same as the external counter.
> 
> Another method that provides even greater accuracy is the method outlined on
> the Elecraft website on the Builder's Resource page -
> http://www.elecraft.com/Apps/K2%20C22%20Adjust%20App%20Note.pdf.
> This method requires no extra calibrated equipment, but there is a requirement
> that the standard station be tuned with precision.  When using WWV, I use
> Spectrogram to observe the audio output tones, knowing that WWV transmits
> tones of 500 and 600 Hz on alternate minutes (there are silent minutes and one
> minute of 440 Hz tone as well).  If the tones line up with my Spectrogram
> markers at 500 and 600 Hz, I know that WWV is properly tuned within one or two
> Hz.
> 
> After setting the 4 MHz reference, run CAL PLL and CAL FIL changing each BFO
> and the resulting frequency should be within 20 Hz of the correct dial
> reading.
> 
> For more information, please refer to my website article on K2 Dial
> Calibration www.qsl.net/w3fpr
> 
> 73,
> Don W3FPR
> 
>     
> 
> 
>