I am having a lot of trouble understanding the proper method to align
the crystal filter section (off the output of 3rd IF transformer)in an
SX-71. The manual suggests "rocking" the signal generator around the
IF frequency (455khz) while turning the IF transformer slug and
monitoring the output level to find a null between two peaks. You are
supposed to set the slug to the null. The output tone is to be created
using the BFO set for 1kz at the IF frequency. I don't understand what
is creating the peaks and null... the rocking of the generator or the
adjusting of the slug? There is a huge null created just by rocking
the generator as the beat frequency drops from 1khz to zero and then
ramps up again on the other side. I can't imagine this is the null,
but it overpowers anything else I am seeing. Then how do I set the
slug at the null point, when its impact is hardly discernible? I could
be out to lunch, but why not use a sweep generator and scope to
actually look at the wave shape being passed through that section of
the IF. Or, why not just adjust the slug to provide the highest peak
at the crystal frequency (which is actually 456.7khz) as is
recommended for the rest of the IF section?

BTW, this is my first communications receiver. Up to now I have been
restoring test equipment, broadcast radios, and a couple of TVs (all
tube gear). Any and all advice would be much appreciated. So far in my
aligning the SX-71, I seem to have increased the ringing caused when
the filter is used to the point it seems hardly useful. I don't know
if that was caused by misadjusting this particular slug, or because I
aligned the rest of the IF to exactly to the crystal instead of just
455khz, which is what they said to do. I have recapped the unit (just
the papers), replaced a few far out of range resistors and changed a
couple of weak tubes.

Dan