[time-nuts] High end OCXO alternatives (or maybe an high perfRb ?)

Bob Camp lists at rtty.us
Thu Dec 8 11:57:09 EST 2011


Hi

A device that's known to be at a legitimate < 5x10^-13 at 100 seconds, will
cost you some money. That's true what ever it is. If it's an OCXO it's also
likely that it will perform at that level at 1 and 10 seconds. An Rb likely
will degrade a bit at the shorter Tau's. An OCXO's stability should degrade
at the longer Tau's, the Rb's should get better out to at least 10,000
seconds. 

You can indeed get lucky and find the one in a hundred part. Often this is
done by getting a hundred parts, and then powering them up for a couple of
months. Test them all for short term and keep the best. Sell the "junk" and
move on..

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Mark Spencer
Sent: Thursday, December 08, 2011 10:28 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] High end OCXO alternatives (or maybe an high perfRb
?)

Bert, that is a good question and thanks for your feedback.     

At this point the answer is it depends (:  (On availability, price etc..)

To add a bit more context to this matter, I believe I'm somewhat limited by
my measurement systems at Tau's of significantly less than 100 seconds or so
(I've got two 5370B's and a Tek 2252 scope that can work as Time interval
counter and feed data into time lab, each instrument has it's pros and cons
but I don't have a lot of confidence in my measurements at Tau's of less
than 100 seconds where as measurements at 100 seconds and greater a
repeatable between different instruments etc..)

In the long run I'll probably look at getting equipment to measure shorter
tau's and phase noise but that's another project for another year or more
likely another decade, but getting an OCXO  now that would be usefull later
on makes some sense as well.

If I had to put a stick in the ground I'd likely settle for 5E-13 or less at
a tau of 100 seconds.   I'm not that worried about performance at shorter
tau's at this time.   I realize that OCXO's typically exceed their specs if
left running in a stable environment (as I suspect my FTS 1050 is doing.)

Thanks for the comments about the HP 5065.

Regards
Mark




--- On Thu, 12/8/11, EWKehren at aol.com <EWKehren at aol.com> wrote:

> From: EWKehren at aol.com <EWKehren at aol.com>
> Subject: Re: [time-nuts] High end OCXO alternatives (or maybe an high perf
Rb ?)
> To: time-nuts at febo.com
> Received: Thursday, December 8, 2011, 10:00 AM
> Mark
> 10E-13 at 100 sec is  a wide range. What about at 1
> and 10 sec. and  are 
> you talking about 3, 5, 9 E-13.
> I personally have quite a few 10811's that brake the 1E-12
> from 1 to 100  
> seconds my best OCXO is a Datum 1000 that is 3.5E-13 at 1
> sec.  and 4 at 10  
> and 7 at 100 sec. I control it with a FRK-H which has 7E-13
> at 100 sec. 
> In this range short of a $ 15 000 Oscilloquartz the best is
> a HP 5065. They 
>  all are below 1 E-12  some as low as 1E-13 at 100
> sec. but the only  way I 
> know how you know what you are getting is work with Corby
> Dawson.
> Bert Kehren
>  
>  
> In a message dated 12/7/2011 9:41:56 P.M. Eastern Standard
> Time,  
> mspencer12345 at yahoo.ca
> writes:
> 
> Greetings:
> 
> I'm contemplating starting a search on the  "typical
> auction sites" for a 
> high end OCXO (or possibly a high end Rb) that  would
> be suitable for 
> characterizing the performance of an FTS 
> 1050.   From time to time I've seen ADEV 
> figures of in the 10E-13  range (at a typical Tau of
> 100 seconds) when 
> comparing the FTS 1050 in  question to one of my
> GPSDO's and one of my Rb's.    
> 
> At this  point I'm contemplating looking for:
> 
> Another FTS 1050
> Various Datum  / FTS stand alone OCXO's
> An Oscilloquartz BVA OCXO
> A Sulzer  OCXO
> Maybe an HP 5065
> 
> (I've already assembled a modest collection of  half a
> dozen various 
> 10811's and don't really want to buy any more at this 
> point.)
> 
> Essentially I'm looking for something with a reasonable
> likely  hood of 
> consistently having an ADEV in the 13's at Taus of 100
> seconds or  so.   
> I'm thinking that another FTS 1050 is probably the
> most  likely alternative 
> but I'm trying to keep an open mind to other
> options.   I'm not really 
> interested in a Cesium standard but if anyone has any
> other  suggestions of 
> products I could look for (other than a H maser
> (:   )  comments on or off list 
> would be appreciated.
> 
> 
> Regards Mark  Spencer
> 
> 
> 
> 
> 
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