[R-390] 2nd LO xtal measurement

[Alan Victor]

So for completness and maybe secondary information, I measured the bad vs.
the good R-390A 2nd LO xtals. The bad is a 9 MHz unit and some good are 10
and 13 MHz. All are fundamental xtals and I would have to look up their
spec but, I assume the correlation C for these xtals is ~ 32 pF. In any
case, measure them on a VNA results in the following:

*xtal                       Z at desired frequency   R at series resonant
freq*
9 MHz                   500 +j 5000 ohm           45 ohm
10 MHz                  7.5 +j 505 ohm             7.5 ohm
13 MHz                  9.0 +j553 ohm              9 ohm

If you search for the frequency where the 9 MHz xtal correlates with 32 pF,
its 8.99441 MHz or about 5500 Hz off.
Now, I would need to check if 32 pF is the right number,  but this error is
about what I saw for this unit when
operating on the 7 MHz band, about 15 KHz error. So the xtal is not
fractured, its not broken and it functions. That
is to say it looks like a xtal, just not a very good one and not usable in
the receiver.