Rick said: a bunch of good stuff
Now, that is the kind of answers I'm talking about.
I can have a 10811 inside a sealed Tupperware container filled with dry
nitrogen and under a dual control that keeps both its temperature and
pressure constant before you can think crazy idea.
Rick,
Care to comment if anything special was done to control the EFC noise due to
the internal 1/f voltage noise of the zener reference?
Even for a selected one, It is still in the PPM range, which would causes
6uV of noise on the EFC.
Maybe for most of its spec, an insignificant amount, but for a true extreme
nut, a real and measurable and troublesome amount.
ws
*****************
----- Original Message -----
From: "Rick Karlquist" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Tuesday, March 30, 2010 11:16 AM
Subject: Re: [time-nuts] Making a HP 10811 better
It has been interesting reading all the 10811 ideas.
I haven't had time to respond to them individually.
I would recommend reading my oven paper:
http://www.karlquist.com/oven.pdf
which will put some of the oven ideas in perspective.
With tweaking, we could get the thermal gain of the
E1938A over 1 million using just a single oven and
nothing exotic. In production they ran in the several
100,000's.
I would also note that the 10811 has a fairly substantial
humidity coefficient of frequency. Thus the first order
of business is to get the hermetic version of the 10811.
The common version that is open is never going to be
immune from the environment.
The E1938A was immune from humidity effects, even though
it was not hermetic. It was nearly immune from temperature
effects as well. It still had the same 2G turnover effects
as well as crystal frequency jumps, since the crystal was
essentially the same as the 10811 crystal. You would never
mistake an E1938A for a Rb standard by looking at a strip
chart. The best that any 10811 could do would be to
approach E1938A performance.
But go ahead, have fun and learn!
Rick Karlquist N6RK
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