[TenTec] Re: Aligning Omni VI+ Freq "Jump"

[Bill Cook]

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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