[time-nuts] Making a HP 10811 better

WarrenS warrensjmail-one at yahoo.com
Tue Mar 30 20:53:49 UTC 2010


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" <richard at karlquist.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
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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