[time-nuts] OCXO sensitive to gravity

[WarrenS]

When possible, the thing I do to eliminate the effect of small gravitational changes or tilt 
from effecting the Freq of my Oscillators, is to orientate their case so that the osc is approximately at its MAXIMUM 2G turn over axes. 
This gives the osc a null to small gravitational changes, much the same as setting the temp of an oven to the zero TC freq turn over point.
To optimize further, the axes can be fine adjusted so that a small tilt in any direction causes the same direction in freq shift.
The improvement achieved can be quick substantial like 100 to 1 improvement. 

ws
*******************
----- Original Message ----- 
From: <SAIDJACK at aol.com>
To: <time-nuts at febo.com>
Sent: Thursday, August 13, 2009 5:14 PM
Subject: Re: [time-nuts] OCXO sensitive to gravity


> Hi there,
> 
> there are special low-g OCXO's out there. We offer one that has better than 
> 3E-010 per g per axis, which is about 10x better than your "standard"  
> OCXO.
> 
> This is also important for stationary applications where the unit is not  
> tilted, for vibration-induced phase-noise is also that much smaller with a 
> low-g  OCXO versus a standard OCXO.
> 
> bye,
> Said
> 
> 
> In a message dated 8/13/2009 11:02:51 Pacific Daylight Time,  
> wpxs472 at gmail.com writes:
> 
> A while  back there was some discussion about crystal oscillator's  changing
> frequency due to the effects of gravity. Since I got my Z3801 up  and 
> running
> full time, I have been trying to characterize some OCXOs I had  picked off
> eBay but had no specifications for. I was trying to fine tune  one to the
> '3801 and noticed that when I picked it up and tilted it to get  to the
> adjustment , the frequency changed. I started rotating it 90 degrees  at at
> time and noticed that the frequency changed up or down depending on  which 
> it
> was oriented. The change was immediate and quite noticeable. It is  nice to
> have something as stable as the Z3801 but now I realize all those  OCXOs I
> thought were so great, aren't. I do see why the rubidium sources  are well
> liked. They lock in a couple of minutes and that's pretty much it.  The ones
> I bought off eBay were both off by about 1E-9. It occurred to me  that they
> probably in equipment where they were locked to GPS and with  nothing
> connected to the frequency control input, they would naturally be a  little
> off.
> _______________________________________________
> 
> 
>