[Elecraft] BFO on wrong sideband?

[Don Wilhelm]

Tom,

Go to my website www.w3fpr.com and study the article on K2 Dial 
Calibration.  Part 3 of that article deals with setting the K2 filters.  
If you are not familiar with the use of Spectrogram for setting the K2 
filters, I strongly suggest that you become familiar with it.  Once you 
have used Spectrogram for that task once, doing it a second time is like 
"falling off a log".  Your K2 performance will be much better for the 
effort, and your ears will thank you.

Yes, it is easy to get the BFOs on the wrong sideband by accident.  Tune 
to a band below 15 meters when setting the filters - 40 meters is 
recommended for consistency, but others will do.  There is a sideband 
reversal that takes place at 15 meters and higher, and using those bands 
for setting the filters will only cause confusion and the resulting 
frustrations that accompany such confusion.
To prevent having the BFO on the wrong sideband, remember that the CW 
filter BFO frequencies (and/or DAC values) must be lower than the CWr 
BFO frequencies.  Normal CW BFOs will have a frequency in the 4912.8 to 
4913.5 kHz range while the CWr BFO frequencies will be in the 4914.2 to 
4915.5 kHz range.

Likewise, the SSB USB BFO frequencies will be higher than LSB and the 
RTTYr BFOs will be higher than the RTTY BFOs.

Do these things in order.
1) Set the 4 MHz oscillator - use Wayne Burdick's (N6KR) method and view 
the 500 and 600 Hz tones transmitted by WWV on the Spectrogram display 
to be certain you have tuned WWV correctly (the K2 should be in LSB or 
USB mode).  Then enter the menu for CAL FCTR  and alternate the internal 
counter probe between TP2 and TP1 while adjusting C22 - you are looking 
for the point where the lower order digits on the display are the same 
at both points.  The frequency at TP1 moves about 5 times faster than at 
TP2, so when doing the adjustment of C22, put the probe in TP1 - it is 
just easier that way.
2) Run CAL PLL (remember to put the probe in TP1 and the band to 40 meters).
3) Now put a noise source on the K2 antenna input and adjust the BFO 
frequencies (CAL FIL) to place the filter passband at the desired 
frequency on the Spectrogram display.  Do that for *all* BFOs.  If the 
passband position is already correct, move it up a notch and then back 
to the original - that will tell the K2 that the BFO has been changed 
and it will write new EEPROM values based on the new 4 MHz oscillator 
frequency, and that is exactly what you want to accomplish.

When you are done, check the tuning of WWV - it should be within 20 Hz 
which is the DAC limit or the K2 (look at the tones transmitted by WWV 
to verify)

73,
Don W3FPR

Tom Campie wrote:
> I just got my K2 used and I went through and adjusted the CW filters  
> because I like mine lower than the previous owner but i have  a  
> feeling I botched it up - I'm zero beat to the ARRL at 14.046.84, and  
> they transmit on 14.047.5 MHz.    I also tried re-aligning the VFO  
> based on a zero beat on WWWV so I'm not sure where I'm wrong.  Please  
> help!
>
> Tom W0EA
>   
>