yes, I found the brief article and the cite is 73 Amateur Radio Magazine,
August 1989, p.53, "IF Shift, Cheap - Easy IF Shift Add-on to your Older
Rig" by Terry F. Staudt, LPE, W0WUZ (LPE is licensed professional
engineer, IIRC?). He reviewed a number of 1970s upgraded receivers (A, S,
or Mk II versions ;-), and discovered how they did IF shift or passband
tuning in those updated models. The modification uses a varicap Motorola
MV 1872 and a pot and trimmer capacitor to vary the first IF transformer
frequency. He added it to a Galaxy V mk II transceiver, noting "the
circuit works wonders". You do have to make two adjustments to the
modified IF transformer to preserve selectivity etc., which he describes
briefly ;-)

If you can't find the article locally, let me know, email me directly with
your address to and I'll mail you a photocopy.

Drake IF tuning, IIRC, the R4C had an odd "feature" (aka bug ;-) in
that it didn't provide IF or passband tuning in all modes, as the earlier
Drake R4B did, although you could modify the R4C to do so (and other
mods too).

I probably shouldn't note that I found another 73 article in my search
that discusses how crystal filters could be built to provide any desired
CW or SSB bandwidth (though you might have to grind a crystal or two to
get precisely the bandwidth you want ;-) ;-)

grins ;-) bobm

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* Robert Monaghan POB 752182 Southern Methodist Univ. Dallas Tx 75275 *
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