[Collins] Re: QRZ ALL R388 EXPERTS




It seems to me that the ORIGINAL QUERY hasn't been carefully considered.  Though
it's been years since I've worked on an R388 or 51J I couldn't continue to sit
on the sidelines mute so I dragged out my military manual for the R388.

Sure enough, it states under "Variable Intermediate Frequency" that

     "The variable intermediate frequency consist of two ranges:
     one for a frequency of 2.5 to 1.5 mc, and the other for 3.5 to 2.5
     mc, used on even-numbered and odd-numbered bands, respectively.
     Using two variable i-f bands in this manner, cuts in half the number
     of crystals necessary in the h-f oscillator..."

This should be an obvious clue to think about since the original post talks
about EVERY OTHER BAND being off.

>>  The frequency alignment (the dial
> > setting) seems to shift by the same amount as I change to every
> > other band position.

Hmmm.... wouldn't you think that might have something to do with the alternating
use of different IF frequencies???  For band segment 4 and up, on one band
segment the signal goes into the FIRST MIXER and in the next it goes into the
SECOND MIXER using the different IF frequency on alternate bands.

I'd sure want to do a careful alignment using a decent counter to set the
frequencies used BEFORE I go off on a tangent of buying a whole set of crystals
to replace for fear that they are all bad with age.  (Even without a careful
alignment it would be possible to "split" the difference so bands were all
within 2.5 kc of the same on the dial if you didn't want to do an alignment.)

Just my two cents worth!

Ian, K6SDE



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