RICHARD ANDREN wrote:
> Thanks for the correct alignment procedure Bill. One last question. What
> are the frequency ranges of each of the four 10 meter sub-bands?
>
> 73, Rick AE9D
> -------------
The four sections of the Ten meter band are as
follows:
xtal 10a 28.0-28.5
xtal 10b 28.5-29.0
xtal 10c 29.0-29.5
xtal 10d 29.5-30.0
The computer bd. (logic bd) automagically switches in the correct xtal when
the crossover points are reached. I think there are differences between tuning
upwards as opposed to tuning downwards in the actual crossover frequency.
This probably has to do with the 5.0-5.5 VFO having approx 30khz over on each
end.
The Omni VI() is a "pretty good radio". However it is built to a price (like
anything else for that matter) and can be improved without altering the basic
design.
Some of "US" like a good transciever without all the
bells and whistles.
Changes that I am thinking about: (by priority)
Enclosing the computer bd. and filtering every
line into and out of it. A major undertaking
but worth it for weak signal work. This is my
biggest complaint about the OMNI VI(). Too
much digital noise which is rather common
place in the RF world anyway.
Installing a 4pole 2.4khz xtal filter (for IF noise)
right in front of the product detector which
should be a doubly balanced type instead of
the singly balanced one we have. Gain
distribution becomes an issue here because
of the product detector gain. If just the filter is
done, 10db more gain can be had by removing
the 10db pad on the output of the 6meg IF bd.
Crystalonics is back in business and they
make the power fets that Dr. Rhode used to
reccommend for post mixer amps etc. They
have a web site and it looks like they sell in
small quantities. The CP640 looks great for
the RF amp and the CP643 (which I have) does
provide a 50ohm resistive load for the first
mixer.
Phew! enuff fer now
Bill N4WC 73
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