On 6/3/17 5:54 PM, Bob kb8tq wrote:
Hi
The objective of the early work with coolers and OCXO’s was DOD sponsored. Low
cost was
not the goal :) The idea was that aging might be much better at the lower turn
than at the upper turn. Once they
played around a bit they found that activation energy was a real thing in this
case. The improvement in aging
did not justify the significant increase in complexity of the design. The idea
has popped up about every ten
years. Each time the conclusion after building a trial unit is pretty much the
same.
I'm just picturing in my mind a 14 inch high rack mount unit with
several hundred watts in heater power for the vacuum tube amplifiers,
etc. needed to implement this kind of thing in the early 50s.
I'll bet someone also built one with mechanical refrigeration, a liquid
cooling loop, and an electronic heater. That one was a full rack
cabinet<grin>
The "idea popping up every 10 years" is not restricted to crystal
oscillators. Anything where there's a "the technology doesn't support
it" is the barrier. A couple generations and all of a sudden you can do
it. And sometimes it works - DDS and PN codes are examples of things
which were barely feasible some decades ago, so people went through all
sorts of gyrations to achieve goals with out it, but now, it's "oh yeah,
sure, a parallel correlator to acquire and track 32 simultaneous GPS
signals, isn't there an Arduino Sketch for that?"
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