[time-nuts] OCXO sensitive to gravity

Tom Duckworth tomduck at comcast.net
Thu Aug 13 21:52:30 UTC 2009


The orientation change is due more to the earth's magnetic flux effect on 
the oscillator, and less so from gravity.

Tom
Tom Duckworth
tomduck at comcast.net
----- Original Message ----- 
From: "John Green" <wpxs472 at gmail.com>
To: <time-nuts at febo.com>
Sent: Thursday, August 13, 2009 11:02 AM
Subject: [time-nuts] OCXO sensitive to gravity


>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.
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