[Elecraft] Zero beat WWV

[Don Wilhelm]

Dave,

Maybe now I understand where your problem is - I suggest you proceed as 
follows:

First, adjust the filters so the passbands for all the filters you will 
use are positioned properly.  Use Spectrogram and a noise input to the 
K2 to see where the passbands are positioned.  This is the initial 
adjustment of the filters - you are looking only to position the 
passband at this point.

Then adjust the 4 MHz oscillator (C22) accurately.  Do that as follows:
1) Tune in WWV correctly in LSB or USB mode (ignore the dial reading)
2) Enter CAL FCTR and alternate the counter probe between TP1 and TP2 - 
if the low order digits are not the same, adust C22 until they are the 
same. Do not change C22 from that setting unless you start all over again.

Put the probe into TP1, switch to 40 meters and run CAL PLL.

When CAL PLL has finished, put the probe in TP2 and enter CAL FIL. 
There is no need to reposition the passbands since you have already done 
that, but you need to force the K2 to write new BFO values into the 
EEPROM - so proceed as follows:
1) Set the mode to LSB FL1 and tap the BAND- button.  You should see 
FL1t nnn (where nnn is some number) in the display.
2) Note the number in the display and change it to the next number (up 
or down), then set it back to the original number.
3) Tap the XFIL button to move to LSB FL2 - change its number and change 
it back.
4) Tap XFIL again to move to FL3 and do the same thing - repeat for FL4 
and then return to FL1.
5) Tap the MODE button to change to USB and repeat steps 2 thru 4 above.
6) do the same thing for CW, CWr, and if you have RTTY turned on, do the 
same for RTTY and RTTYr.

When you have done those steps (in order) then exit the menu, switch to 
10 MHz, tune WWV in LSB mode again to check your work - the frequency 
displayed should be within 20 Hz of 10,000.00 - if it is not, start over 
at the 4 MHz reference adjustment to refine that setting and follow 
through the steps again.

If WWV does tune correctly in LSB mode, switch to CW mode and you should 
hear the WWV carrier appear at the audio frequency that you have set for 
the sidetone pitch.  If that is true, your K2 is properly calibrated.

The adjustment of C22 will do nothing during normal operation of the K2.
The 4 MHz oscillator can drift all over the map and you will not notice 
any change.  The K2 does not dynamically use the reference oscillator 
for frequency determination in normal operation.  However, it does have 
to be accurate before doing the CAL PLL or the CAL FIL procedures, 
because it IS used during those procedures to determine the frequency of 
whichever point the probe is connected to - the resulting frequency 
values are then written into EEPROM and the EEPROM values are used 
afterward to determine the frequency readout.

73,
Don W3FPR


David Wilburn wrote:
> Good stuff Don.  Thanks.  Yea, the 9999.99, I was not worried about at 
> all.  It is the 1300 Hz I have to wander over to, to get the CW signal 
> that is bothering me.  I am experiencing the same thing with local 
> signals, I have generated from other radios.  I will check out WWV 
> during the quiet time and see what I find.
> 
> As far as "Just adjust the CW BFOs so the passband is centered...", what 
> are you telling me to do here?  I have run through c22 adjustment 
> (started out at 10000.09 for WWV, and got to 9999.99 using the "Wayne" 
> method), CAL PLL and CAL FIL (with Spectrogram) at least 3 times. Should 
> I go back and do the BFO test?
> 
> Admittedly, it is possible, even likely, that I am making the same 
> mistake each time I have run them.  I have seen the U and L frequency 
> readout get better, but not the CW.  Additionally, it transmits on the 
> correct frequency.
> 
> David Wilburn
> dave.wilburn at verizon.net
> K4DGW
> K2 #5982
>