----- Original Message -----
From: "Hal Murray" <[email protected]>
To: "Bob Albert" <[email protected]>; "Discussion of precise time and
frequency measurement" <[email protected]>
Cc: <[email protected]>
Sent: Sunday, March 02, 2014 2:45 AM
Subject: Re: [time-nuts] Another "atomic" clock question
[email protected] said:
Okay you want numbers. Well, I think 10 ppb or thereabouts should do it.
Somewhere there is a discontinuity in accuracy plotted against cost and I
don't want to cross that barrier just yet. If I can get 1 ppb without a
big
increase in cost, I'll take that.
How good is your crystal?
Junk crystals are good thermometers. Ballpark is 1 ppm/degree-C
If you are running ntpd, turn on loopstats and measure the temperature...
http://www.megapathdsl.net/~hmurray/ntp/slope.gif
I've been watching a 3 MHz ovenized crystal. It was something like 4 for
$25
from ebay. It's a 2 in sq can, over an inch high. It's got a few ppb of
noise over minutes/hours and a few more ppb of drift/wander over
days/months.
It took several weeks to stabilize after power on.
--
Is that 3 MHz OCXO one from Ridge? If so, I opened one up and was surprised
to find it did not have any foam insulation.
Tom
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