[time-nuts] Making a HP 10811 better

WarrenS warrensjmail-one at yahoo.com
Sat Mar 27 17:21:27 UTC 2010


Pete2

Addressing your first question only, I'll let the experts address the why.

Yes, I 'think' it does in principal, I would not guess on how long it takes 
though.
But
I have not checked that close to be sure.
I'd never do something that gross during the middle of a test that I was 
trying to see 1e-12 things.
I do that first thing, long before the high resolution test starts and then 
let things resettle before proceeding.
Any change in cable position or the Osc moving a bit in its Box or a dozen 
other things could also change it that much, including temp gradients in the 
box, so Don't do that if you want 1e-12 results.
Use the wedge, that I have tested, and is completely reversible and 
repeatable at those levels.
I have noticed that the OSC will even take a long time to resettle  (hrs+ ) 
if the EFC voltage is change a lot and then put back.
Which is why I limit the clamp voltage of my Tbolt to typ + - 100 mv or less 
from its nominal.

ws

********************


> Warren,
>     If you turn over an oscillator, is the frequency change
> completely reversible (to your "under 1e-12 resolution") when it is
> restored?  Thinking aloud, if an hour-glass is turned over twice, the
> final level will be the same, but the grains will be mixed.  A quartz
> crystal, however, is solid, so hopefully nothing actually moves.
> Presumably the zero-G axis is with the axis of oscillation at 90
> degrees to gravity?
>
>     Peter (the "other" one :-)
>
***************************>
>
>> Another thing I use it for is to test high resolution Freq meters.
>> Using a calibrated wedge that I can then slide under one edge of the 
>> zero-G
>> Osc box, I can
>> make small, variable, repeatable, freq changes of under 1e-12 resolution,
>> something pretty hard to do otherwise.
>> If I want to make BIG changes like 1e-10, I can rotate the box on any of 
>> its
>> sides and still use the wedge,
>> and for a quick check of new equipment, I just turn the box over which 
>> then
>> gives a couple of parts in 1e-9 freq change.
>> It makes a weird but simple and indispensable variable freq source that 
>> is
>> useful for many things, such as checking the LOOP TC of a TBolt.
>
>
> 





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