[time-nuts] Making a HP 10811 better

[Bob Camp]

Hi

If that's the result you are getting, you are measuring something other than G sensitivity. Temperature effects possibly.

Bob


On Mar 27, 2010, at 11:02 PM, WarrenS wrote:

> 
> Just a friendly comment about the Zero G turn over point and Vibration
> 
> Like Zero temp turn over, Special orientation of the OSC ONLY works good over a VERY SMALL range, (maybe a 1/100 of G change)
> It would not help vibration and has no effect on microphonics which are likely a bigger problem anyway.
> Try taping you Osc, It's freq will go crazy if monitoring it at high resolutions and bandwidths
> 
> ws
> 
> ************************
> 
> Hi
> 
> The concrete basement floor is your friend.
> 
> Stay as far away from the blower on the furnace as you can. If you have a drop forge in the basement avoid it as well :)....
> 
> You will indeed have a seismograph, but not a very useful one. There's not a lot of G's at seismic frequencies unless you live in an active earthquake region. The fundamentals of G's and displacement vs frequency are in your favor in that respect.
> 
> Bob
> 
> 
> On Mar 27, 2010, at 12:42 PM, Stanley Reynolds wrote:
> 
>> Is the source of the vibration important ? I'm thinking that any vibration that is not on the same axis as gravity. Walking across the lab vs a fan that is out of balance close by. Would a suspended mass mounting help with vibration isolation and damping with rubber pads and springs or would that just make a seismograph ?
>> 
>> Stanley
>> 
>> 
>> ----- Original Message ----
>> From: Peter Vince <pvince at theiet.org>
>> To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
>> Sent: Sat, March 27, 2010 10:51:07 AM
>> Subject: Re: [time-nuts] Making a HP 10811 better
>> 
>> 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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> 
> 
> 
> 
> 
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