[Elecraft] Re: KX1 BFO Calibration

[Wayne Burdick]

Hi Randy,

This should never happen. Typical BFO corrections are on the order of -0.20. We
match the crystals very closely.

It sounds as if your BFO is way off frequency frequency. Do you have a frequency
counter? If so, you can touch it to pin 7 of the product detector (NE602, U4) to
see what the actual BFO frequency is. Check all components in this area; you
could have the wrong value of C13, C14, or L10. 

Also check the labeling on your BFO crystals. We have to make sure you didn't
get the wrong type. They should all have the same markings.

Wayne
N6KR

Randy Foltz wrote:
> 
> After making several 40 m QSOs, I decided to do the BFO calibration.
> After a 15 minute warm up period I tuned CHU at 7.335 MHz.  The BFO
> parameter was set to .00 and the DDS one to 00.  Using Spectrogram to
> display the 1000 Hz tick marks I recorded the fq as 7334.74 in USB and
> 7337.35 in LSB.  This difference is 2.61 and when divided by 2 gives a
> BFO correction of 1.30. Since the USB was lower the correction should be
> -1.30.  Woops, the maximum negative value is 0.99.
> 
> I went ahead and set the -0.99 and recorded the fqs again.  This time
> they were 7335.74 for USB and 7336.36 for LSB.  Closer together, but
> still not the same.
> 
> I took out the ATU, repeated the test, and the results were the same....

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