[DSP-10] Re: DSP-10

[Michael Lodico]

dave garnier - wb9own something that is not mentioned in those links is
component aging.  I worked several years for a company that made OCXO's
and did the design work on them which also involved stability over time
issues.  These are some of my findings that may help others.

1)  Aging of the crystal blank is controlled by the cut of the blank,
quality of the blank, the blank holder, the plating on the crystal, the
back fill gas and Crystal Room aging requirements which can vary from
mfg to mfg.

2)  There are 2 types of electrical aging that goes on with an OCXO.
The first is the drive current on the crystal and the second is the
parts aging from a current in the support circuit.

3) The temperature aging process.  The crystal ages at one rate while
the components age at a different rate depending on the temperatures
involved.

So with so many variables involved the ideal OCXO would have the
crystals aged in the Crystal Room for 30 days using temps going from
-20C to 80C or higher with a drive current on them.  The parts for the
OCXO would be aged 30 days using the same temp ranges and an electrical
current going through each part.  The container for the OCXO would be a
vacuum thermos bottle.   Needless to say these are very expensive OCXO's
and are almost considered standards.

Now for what you can do to improve what you may have the best thing
would be to cycle it for 30 days going from your freezer to an 80C oven
with a voltage applied several times a day.  After this time frame then
use a freq. standard to recalibrate your OCXO and you should achieve
minimal drift and stability over the long term.  I hope this info is of
some use to people.

Mike Lodico
K1EG