[time-nuts] Compairing two GPSDOs Oscillators

William H. Fite omniryx at gmail.com
Sun Nov 14 22:23:43 UTC 2010


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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