[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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