[time-nuts] Making a HP 10811 better

WarrenS warrensjmail-one at yahoo.com
Sat Mar 27 00:46:17 UTC 2010


Neville Michie asked
>Does it make the double oven unnecessary?

Great point, Don't know, Have not tried it on that unit.
I've done it on cheapie Osc and it helps a lot Sometimes, if they have a 
turn over point at a reasonable temp.
Guess it depends in part on how close they got it in the first place and if 
there are other things that case temperature hysteresis with small changes.

As long as the effect of temp is somewhat linear and repeatable over small 
Room temp changes, then that or any number of other things should help.
I'll add it to the middle of my list.
It's actually pretty quick to find out for any given unit, cause I can 
separate out the effects of aging and new drift that is cause by playing 
with it and the effect of changing temp.

That all said, I hate HOT ovens for anything that I want to be long term 
stable.
If I have a choice, I set its oven operating temp JUST above max room temp.
Or
Thanks to Mark and Lady Heather
with the Tbolt, I set it's temp just Below room temp and let it self heat 
and cool it down with a fan.
Makes for a nice failsafe oven control system.

ws

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

Warren,
there is a report somewhere of resetting the oven temp in a HP 10811
to exactly find the turnover temperature.
How high is this on your list of things to do to improve a HP 10811?
Does it make the double oven unnecessary?

cheers, Neville Michie
****************
On 27/03/2010, at 10:49 AM, WarrenS wrote:

>
> I was asked:
>> "what advantage is there to those of us, on stable ground and not
>> in rolling ships, of finding an orientation where any rotation
>> will move the frequency in one direction?"
>
> My answer to a Good question:
> When the Osc is orientated so that any tilt angle changes its freq
> in the same direction,
> then it is at the Zero-G turn over point and the slope of freq
> difference vs. angle is at zero.
> This causes small angle changes to have very little effect on the
> freq.
> Works about the same way as finding the turn over temperature of an
> crystal.
> that said,
> It's mostly still just about NS  "nuttery stuff".
> The Zero-G effect only works great for very small angles,
> like lifting an edge less than a 1/8 to a 1/4 inch.
>
> The right orientation can make a difference, though.
> The stuff that I'm working on is setting on my work bench where I'm
> looking for things that cause small freq changes of 1e-12 or less.
> If the Osc is not in the right orientation, then any movement of
> it, will change its freq, more like a tilt meter than a stable Osc.
> If you want to make a very sensitive tilt angle meter all one needs
> do is set the Osc box on any of its sides.
>
> 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.
>
> ws
> ***********************
>>
>> Peter asked:
>>> "Could you post a drawing or photo showing the proper orientation
>>> of the
>>> zero-G axis?"
>>
>>     Simple answer ... NO  see Bob's response on why.
>>
>> BUT probable because they are made very similar, the double oven
>> units I've done it to, all end up at about the same angle.
>> Just imagine the worse possible angle to try and mount it (on one
>> of its corners) and that'll be close :-).
>> I hold them in place with a bunch of specially cut and shaped foam
>> stuffed all in a slightly bigger but tight fitting box.
>>
>> It helps to have a fast reading High resolution freq difference
>> meter to find and do fine adjustment on their final angle.
>> I do each axes separately. The final results you want is when no
>> matter which way it is tipped, The freq always moves the same
>> direction.
>> The improvement for small angles is really amazing, up to 100
>> times better.
>> BTW there are two zero-G turn over points, one is at min freq and
>> one is at max freq, which are about 180 deg different from each.
>> This is good to remember in order to place it so that you can get
>> its cables out.
>>
>> ws
>> *****************
>> Hi
>> The true zero axis will be different for each individual oscillator.
>> Bob
>> *************
>> Behalf Of Peter Putnam
>> Sent: Friday, March 26, 2010 12:08 PM
>>
>> Warren,
>>
>> Could you post a drawing or photo showing the proper orientation
>> of the
>> zero-G axis?
>>
>> Thanks,
>> Peter
>>
>> ****************
>>
>> WarrenS wrote
>>
>>      ... snip .... snip ....
>>
>>> I know how to make major improvements to the 10811 so that the
>>> standard stuff does not have ANY measurable effect on its freq.
>>> Nothing really magic, mostly simple things like secondary PS
>>> regulators, an outer oven heater wrap and controller, some internal
>>> span and reference voltage adjustments, tilt it on its Zero G axes,
>>> add an RF buffer, isolate or have a less sensitive EFC input, a fine
>>> freq adjustment pot, and probable others once I get into it more.
>>>
>>> ws
>>
>>
>> 





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