[time-nuts] Making a HP 10811 better

[WarrenS]

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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