Posted by
Rich Lentz on
Jan 03, 2005; 11:44pm
URL: http://elecraft.85.s1.nabble.com/A-minor-C22-question-tp373225p373230.html
Did you re-run CAL PLL, ** AND ** XFIL on ** ALL ** Modes (USB, LSB, CW,
CWR, RTTY, & RTTYR)
** AND ** when running CAL XFIL you MUST change the number (up or down at
least on digit and then back to the same number) so that the MCU knows that
it needs to re-store the frequency settings for the BFO.
Otherwise you have changed nothing but the frequency of the reference
oscillator. For a long explanation see W3FPR's discussion. The short one
is that the MCU stores a digit representing the voltage necessary to make
the frequency. This is "number" determined by the Reference oscillator
whose accuracy determines the repeatability and accuracy across all bands.
In other words the 4.0 MHz oscillator is only used for the frequency
measurement. It only measures the frequency when you run the CAL FILL and
CAL XFIL. After that it does nothing.
Rich,
KE0X
---------------
Last night I redid my C22 reference oscillator adjustment using WWV on 10mhz
as the zero beat reference. This is the third time I have adjusted C22 and
each time I am able to adjust C22 to a precise offset balancing TP1 and TP2.
However, when I put the cover back on the K2/100 I find that WWV zero beats
a few tens of hz off. (After last night's adjustment, the zero beat was
10000.03) One should expect to be +- 10 hz as that is the finest resolution
of the VCO, but it would be nice to get a little closer.
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