[R-390] Ovens and Synchronization

[Cecil Acuff]

Hey guys,

        Lets talk about the crystal ovens in the 390A.  I seem to remember
it is common practice to not use them anymore for the sake of longevity.

My R-1051 experience is that one can't do without the oven in the Frequency
Standard because without the oven the stability the 1051 is known for goes
down the toilet.  The crystal in the oven was designed to work at a specific
temp to be stabile.  There is a nice flat spot in the curve up around 85C

Is this not the same with the crystal deck, calibrator xtals and maybe to a
lesser degree the PTO in the 390A?

Looking in the Y2K manual it seems recommended to fire them up a few hours
before an alignment but then go back to the practice of turning them off for
our day to day ops....seems that would negate the alignment.  Wouldn't one
be better off doing the alignments in the state one would normally operate
the radio?

I am at the point in my R-390A ownership that I am starting to get technical
with the 390A now that time presents that opportunity.  As a result I guess
I'll be asking some of the typical beginner questions.

Coming to a post near you:  How does one go about putting a radio back
together where everything is totally out of mechanical and electrical sync!

I pulled the whole IF deck apart for complete cleaning....4 years ago.  No
problem on getting everything back together just need some starting point
for getting everything re-synchronized.  It was a nasty blue striper...won't
know it once it's complete....it cleaned up very nicely.  The gear train is
separated from the IF deck chassis and all that is separated from the xtal
deck.

Gear train works like a swiss watch....love that Mobil 1

Thanks in advance!

Cecil Acuff