Humm,
Have to admit, I did not consider that as a possibility before.
Maybe when I tap on it, its not microphonics after all that cause the freq
to modulate, but the vibration of the inside stuff that is warming it up.
For every action there is a reaction and for every nut there is a
wing-it-nut.
ws
*****************
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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