[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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