Re: OT 10Mhz references


 

Hi Dwayne,

Tom Van Baak, one of the most famous of the group known as the "Time-Nuts"
has three Hydrogen Masers. He is in a league of his own. His website is at
http://www.leapsecond.com/

Somewhere on his web site is the story of when he took his kids camping for
a weekend to Paradise which is 7,000 feet up on Mt. Rainier near us in
Seattle. Of course Tom does things a little differently than the rest of us.
He brought 3 HP Cesium Standards up with him on the trip. When he got back
down he compared the time dilation that occurred between the three Cesium
Standards up on the mountain for the weekend with the ones he kept in his
house which is almost at sea level. He then calculated the expected time
difference based on General Relativity.

Tom is a little smarter than most of us. The Time-Nuts are a lot smarter
than I am.

But I know why Craig Sawyers and I have a Trimble Thunderbolt. Even if we
can't keep up with the Time-Nuts it doesn't mean we can't have a time
standard good to 12 digits. Sometimes it's just fun to watch something that
accurate.

Dennis Tillman W7PF.

-----Original Message-----
Sent: Friday, March 11, 2016 10:23 AM
Subject: Re: [TekScopes] Re: OT 10Mhz references

I am curious what you guys are doing that requires that sort of long-term
precision?
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Posted by: Dwayne Verhey <tekscopes@verhey.org>
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Original Message-----
Sent: Friday, March 11, 2016 10:45 AM
Subject: RE: [TekScopes] Re: OT 10Mhz references

I am curious what you guys are doing that requires that sort of long-term
precision?

Because it is there, and affordable. There are those who are a whole lot
worse in that regard. The ultimate reference is a hydrogen maser - and
there are guys out there who have one (have a look at time nuts website) at
many tens of thousands. Or if you want the ultimate in phase noise, a BVA
SC-cut ovenised crystal is almost unbeaten for this
http://www.oscilloquartz.com/files/1363164953-Br_%20OCXO%208607.pdf .
Oscilloquartz were alas acquired and discontinued their world beating
expertise in this difficult corner of technology.

Rakon have taken this up though
file:///F:/Downloads/USO%20HSO14%20Shortform-A1.pdf , but a BVA crystal
oscillator will set you back 10k somethings (dollars, euros, UKP). But
although the phase noise and Allen deviation are astoundingly good, the
frequency will drift in common with all crystal oscillators.

I'm happy though with my humble Trimble - a couple of hundred once you have
the active bullet antenna with a good view of the sky.
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Posted by: "Craig Sawyers" <c.sawyers@tech-enterprise.com>
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