Hi Sam:
I really didn't want to get into the in depth BFO alignment stuff
yet and am hopefully assuming it's on the correct side. My question
arose when I wanted to move the previous owners cw center frequency
up from 500hz to 600hz. Using the instructions I found on:
http://www.n0ss.net/k2_filters_using_gram_v5r17.pdf
Everything went well, the center frequency is now 600hz and the
filters look and sound nice and tight.
Referencing page 8 of the above pdf I ran in to a problem, so it
says. The DAC in CW Normal does is not lower than the determined
center frequency value.
Then I read on page 9 and it says *if* the BFO is on the wrong side,
(which the DAC readings would seem to indicate), one or more filter
setting would show a shift of the center freq and be more than 200hz
off. All the filter settings are dead on, no vfo changes needed when
cycling thru the 4 settings.
The BFO center frequencies shift downward as the bandwidth is
narrowed, so you must determine where 'center' is for each bandwidth.
Then, the CW Normal DAC/Freq. values should ALL be below the filter
center freq determined for EACH bandwidth selected. And the CW
Reverse DAC/Freq. values should all be above filter center.
If you can change bandwidths and not have to re-tune the VFO to
'find' the station, chances are that everything is A-OK.
However, once the filters are aligned for a selected sidetone
frequency, if you change the sidetone freq. the filters will NOT
automatically 'track' the change, you must re-align to the new
sidetone freq. Some folks got the mistaken impression that tracking
was automatic, and it's not.
SO what's the deal here, do I ignore the DAC readings?
Bandwidths used are 1400, 800, 400, 100.
Center freq DAO CW Normal DAO
142 157
135 154
130 152
128 151
These values might well be CORRECT if you are performing the
alignment on 15M and above, but they should be wrong if you are
performing the alignment on bands below 15M. The recommended band for
performing CAL FIL is 40M.
Ah the joys of a rig you can actually work on, heheheh.
Hope this helps. If not gimme a SHOUT!
73,
Tom Hammond N0SS
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