[time-nuts] Timenoob - Cheap and simple 10MHz reference

[Jim Palfreyman]

And started down the dark path you have. You will not have to wait
long before you completely succumb to the dark side.

Jim Palfreyman


2009/12/28 Bob Camp <lists at cq.nu>:
> Hi
>
> Your budget is going to make things tough.
>
> A Thunderbolt needs a triple supply (+12, -12, and +5) to operate. It also needs a GPS antenna of some sort.
>
> The Rubidiums all need a supply and a heat sink. Some of them like the FRS-A need unusual connectors.
>
> They all need to be operated continuously to get the best accuracy. That makes powering them with a shared lab supply impractical.
>
> The Thunderbolt is accurate as a stand alone device because it uses GPS. The rubidiums are all fairly accurate by design, but they would need to be calibrated against something else to be as accurate as the Thunderbolt.
>
> Simple look at it:
>
> If you need ~ 3x10-9 accuracy, then the rubidiums are all fine.
>
> If you need < 2 x10-10 accuracy, then the Thunderbolt is your only choice.
>
> In between those two limits, it depends on a lot of details like how long between calibrations, environment (like temperature), and sources of calibration. Even at the limits I've mentioned, what you are calibrating might impact the choice.
>
> If you have a spare triple output supply already, Then the Thunderbolt is inside your budget. If you do not have a supply, you probably can pick up the pieces on individual auctions with some luck and patience. If you go with a rubidium, look for a dealer who will include the connectors for the device.
>
> One last point: The Thunderbolt *probably* will run for a very long time. The rubidiums may also run for a long time, or they may die 5 or 10 years from now due to lamp wear out.
>
> Lots to think about.
>
> Bob
>
>
> On Dec 27, 2009, at 4:12 PM, Giuseppe Marullo wrote:
>
>> Hi all,
>> just subscribed, I would like a quick advice on a 10MHz reference for calibrating my instruments and for fun. In particular, I would like to know if you could give me advice on EFRATOM FRS-A,FRS-C, DATUM LPRO-101, Thunderbolt and such.
>>
>> I would prefer a GPSDO (like the Thunderbolt), but budget is very tight (about 100EUR), so I am searching old surplus stuff on Ebay.
>>
>> Some examples:
>>
>> http://cgi.ebay.com/Thunderbolt-PRECISION-GPS-10mhz-FREQUENCY-TIME-Standard_W0QQitemZ270504461779QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3efb5285d3
>>
>> http://cgi.ebay.com/EFRATOM-10MHZ-LPRO-101-Rubidium-Frequency-Standard_W0QQitemZ270504461780QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3efb5285d4
>>
>> Any caveat, anything I should ask to the seller? Minimal fw version for the Thunderbolt (2.2 is okay)?
>>
>> Thanks in advance,
>>
>> Giuseppe
>>
>> PS: I am in Italy
>>
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>
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