[R-390] Alignment questions

[Barry]

I've started aligning my "new" R390A.  When I got to the point of being able
to hear AM broadcast stations, I used my frequency counter, tuned the PTO to
the desired frequency (3.455 - 0.770) for a strong local station on 770kc
and set the BFO to 455kc.  At this point, the heterodyne theoretically
should have been zero; however, I was hearing a very high-pitched
heterodyne.

Investigating this, I found the 17mc oscillator is 16.997mc.  This (along
with any inacurracy in the second crystal oscillator frequency) is the cause
of the non-zero beat.

When I originally set the PTO, I tuned it to 3.455 (by frequency counter),
set the counter to x.000 and clamped it together.  If the other oscillators
are dead-on, this would be valid; however that's not the case.

My first question is this: Using one of the crystal deck frequencies that is
the closest, should the PTO be set to accomodate the off-frequency of the
17mc oscillator?  In other words, it won't always track between 3.455 and
2.455 exactly.  To do this, I can loosen the clamp from the Oldham coupler
to the front-panel shaft, dial in a known frequency (say my 770kc station),
set the BFO to 455kc, and while holding the dial at 0.770kc, rotate the PTO
shaft to zero-beat and retighten the clamp.  Is this a good method?

One more question:  For aligning the second IF, the manual states to set the
signal generator to 18.750mc and the R390A to 7.250mc.  I think this should
either be 18.250 & 7.250 or 18.750 & 7.750.  Is this a known issue with the
documentation?  If so, which frequency is correct?

Thanks for reading!

Barry - N4BUQ