Has anyone considered a laser pumped variant like:
http://tf.nist.gov/general/pdf/1009.pdf
Apart from the ECDL laser (can be assembled using readily availalble
parts) it looks fairly straightforward.
Bruce
Tom Van Baak wrote:
Very nice bit of R&D work on Corby's part. Mine is certainly working well
after the modification, but I'm just blown away at the performance seen with
Tom's unit.
Hi John,
Yes, apparently some 5065A respond better than others to Corby's clever mod.
It's clear why there is improvement; it's an interesting challenge/mystery to
understand why some get more improvement than others. I double checked its
performance with both a TSC 5110A/5120A and your TimePod to be sure it wasn't
me.
In general, some HP 5065A are better than others. OTOH, this is somewhat true
for any frequency standard: from pendulum to quartz to rubidium to cesium to
hydrogen. It drives time nuts crazy (and turns some of us into eBay gold
diggers) but this has been the case from the first hand-made quartz oscillators
in the 1920's to, well, the hand-made GPS Rubidium's, or the hand-made cesium
fountains of today.
Every clock is slightly different. You can be practical and live with it, or a
fanatic and keep searching for a slightly better one or finding out why and
putting effort into tweaking parameters, swapping components, or boards, etc. I
know Corby has done an amazing job over the years with vintage cesium and
rubidium standards. I hope to have him upgrade some of my 5065A too.
Just to clarify -- the excellent plot that Corby posted was a modified 5065A that I
tested *for* him, not one that I actually own. So it's not "Tom's unit", but
one that Tom enjoyed testing. Note the baseline was a PHM vs. AHM, just to show the noise
floor of the measurement system(s) and reference(s).
/tvb
Another plot of the "Super" mod that's worth mentioning:
http://www.ke5fx.com/5065A_vs_maser_mask.png
Below 1000 seconds it has no trouble passing the spec limits for a passive
H-maser! For contrast, teeypical LPRO-101 performance is shown in green,
and the red trace is from the second-best commercial Rb standard I've seen
(Symmetricom XPRO).
-- john, KE5FX
Miles Design LLC
-----Original Message-----
From: time-nuts-boun...@febo.com [mailto:time-nuts-
boun...@febo.com] On Behalf Of cdel...@juno.com
Sent: Friday, April 26, 2013 8:24 AM
To: time-nuts@febo.com
Subject: [time-nuts] HP5065B !!!
OK, that was just to get your attention!
What do you call a modified HP 5065A that can give you an Allan Deviation
of 4X10-13 @ 1 Second and 6X10-14 @ 100 Second?
I call it the "SUPER" HP 5065A.
Any of these links will get you to the document describing it.
Have a look and see what it's all about!
Enjoy,
Corby
http://leapsecond.com/corby/Super-5065A-Project.pdf
or
http://leapsecond.com/corby/superproj10.docx
or
http://www.febo.com/pages/HP5065A_SUPER for
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