[time-nuts] Compairing two GPSDOs Oscillators

Bob Camp lists at rtty.us
Mon Nov 15 01:09:39 UTC 2010


Hi

I've been buying them for a while. I put in a lot of bids and win very few auctions. Works for me.

Bob


On Nov 14, 2010, at 5:23 PM, William H. Fite wrote:

> Bob, if you want to let one of those 5370s go, contact me directly:
> omniryx at gmail.com
> 
> 
> 
> On Sun, Nov 14, 2010 at 8:39 AM, Bob Camp <lists at rtty.us> wrote:
> 
>> Hi
>> 
>> There have been a number of HP5370's sell for under $250 on the e place
>> over the past year. I've bought several of them, none for more than $200.
>> The 620 is a rare item. Like a lot of Stanford Research stuff you can get it
>> for X any day of the week or X / 5 when a "real" seller shows up.
>> 
>> Bob
>> 
>> 
>> On Nov 13, 2010, at 11:20 PM, Perry Sandeen wrote:
>> 
>>> List,
>>> 
>>> wrote: > I'm looking for some advice about ways I can compare the
>> frequency of two gpsdo's.
>>> 
>>>> Any thoughts as to what could be obtained used for less than 1K that
>> would be suited for this type of measurement ?
>>> 
>>> OK, Here’s what I use and why.
>>> 
>>> For a GPS receiver: the Lucent RFTG-M-XO GPS KS-24019 L106A.  Google it
>> through Sports Lineup.  $100 to $125 plus shipping all day long.  Sometimes
>> even less.  I got two over a period of time for $100 each including
>> shipping.
>>> 
>>> Why I use them.  At the time I bought them the HP Z series were $300 to
>> $500.  I didn’t want a Trimble from China and they require a PC type power
>> supply.  If I had known about lady heather at the time I might have bought
>> one.  The Lucent uses a single 24 volt power supply.  Also the Trimble
>> oscillators seem to be of a lower quality than the Efratom in the Lucent.
>> That said, a U.S. supplier is offering the latest Trimble W/PS for $150.
>>> 
>>> The downside to the Lucent is you have to use the 15 MHz output or hack
>> it to get the original 10 MHz before it’s up-converted.  For me this hasn’t
>> been a problem.
>>> 
>>> For frequency comparisons I have two HP 5370B TIC’s.  It will resolve
>> time differences of two frequencies down to 10 pico-seconds.  As a counter
>> it reads 16 digits plus sign. It was the last and most complex counter HP
>> made.  I paid $450 for one and $100 for the other. (A steal).
>>> 
>>> Downsides.  They run extremely hot.  One should add some additional
>> fan(s).  Very heavy.  Very large.  The 10811 internal oscillator DOES NOT
>> have EFC.  The best manual setting I could get was within 20 milli-Hz at 15
>> MHz.  It took a lot of time.  Although both pass self-test, the 100
>> pico-second differential test is off by 880 pico-seconds on one and 670
>> pico-seconds on the other.  This would require some serious calibration
>> procedures.  However the error is constant so all one has to do is to
>> remember to add or subtract it depending how you’re measuring.  For 25+ year
>> old equipment I don’t consider that a bad defect.
>>> 
>>> I have 3 tested Lucent Rubidium RFG-M-RB 15 MHz/10 MHz units. One is
>> slightly different but they all work.  I had to run them on the bench for
>> four to eight weeks before their offsets stabilized.  I paid about $100 each
>> with shipping.  All lucent output connectors are SMA so one needs SMA to BNC
>> female adapters.
>>> 
>>> Wrote:> All are in the "sub $300" range on the normal sites. Some are sub
>> $100. All are available with GPIB for logging.
>>> 
>>> I guess I’ve been looking in all the wrong places.  I watch Ebay prices
>> all the time for HP 5370A and B prices.  I’ve never seen one for less that
>> $500.  If there are cheaper places I’d sure like to go looking!
>>> 
>>> SR 620  This is made by Stanford Research.  I agree that it is the best.
>> It can do Allan variations as well.  A current Ebay price: Stanford
>> Research SR620-01 Time Interval Counter $3,250.
>>> 
>>> It’s like the old saying:  How fast can my car go?  Answer:  How much
>> money do you have?
>>> 
>>> IHTH
>>> 
>>> Perrier
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
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