[time-nuts] 10 mhz accuracy for a satellite system

Tue Feb 5 17:26:02 UTC 2019

The two I have are Trimbles with Red & Black Labels with White letters.
It's marked D/C 0635, which if I assume is the Date Code puts them in
2006.

73, Dick, W1KSZ

Sent from Outlook<http://aka.ms/weboutlook>
________________________________
From: time-nuts <time-nuts-bounces at lists.febo.com> on behalf of Bob kb8tq <kb8tq at n1k.org>
Sent: Tuesday, February 5, 2019 8:32 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system

Hi

The parts we typically call TBolt’s  were produced from about 1997 through about 2006.
The date codes on the parts are one way to work out how far along the uint you have is
in that sequence. There are other parts that Trimble produced (produces) under the same
Thunderbolt brand. Those can be quite different beasts depending on which one you
happen to be looking at.

The early parts had OCXO’s labeled “PIEZO” on them. The later parts had a generic
“TRIMBLE” label on them. The PIEZO labels have a date code stamped on them sort
of randomly. The TRIMBLE labels have a field marked “date code”. In all cases I have seen
it’s a two digit year followed by a two digit week.

Anything with a PIEZO label is “early”. Anything from about 2003 on should be a pretty good
OCXO.  There are no guarantees, but that’s a pretty good guess.

There are also changes in the temperature sensor IC and mods to the firmware along the
way. The novel approach to a precision DAC and the resulting “noticeable” temperature
coefficient seems to have been a constant through the entire production run. They also
have various little spurs and noise bumps that some people get into cleaning up.

The good news is that they all (from the first unit to the very last) run very well with LH.
*That* more than any other factor makes them a really good choice. When tuned up,
set up, and monitored with LH, they do much better than they would just running on their own.

Bob

> On Feb 5, 2019, at 9:23 AM, Richard Solomon <w1ksz at outlook.com> wrote:
>
> How does one tell the difference between "early" and "later" ?
>
> S/N, Rev # ??
>
> 73, Dick, W1KSZ
>
> Sent from Outlook<http://aka.ms/weboutlook>
> ________________________________
> From: time-nuts <time-nuts-bounces at lists.febo.com> on behalf of Bob kb8tq <kb8tq at n1k.org>
> Sent: Monday, February 4, 2019 7:23 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
>
> Hi
>
> One thing to watch on the TBolts - the ocxo’s used in them got better as the
> years went by. An early one likely will not do quite as well as a later one. They
> also updated the firmware as time went by, same basic issue - later is probably
> better ….
>
> Bob
>
>> On Feb 4, 2019, at 8:51 PM, Richard Solomon <w1ksz at outlook.com> wrote:
>>
>> There have been some Trimble Thunderbolts over on that auction site
>> that were being sold for $80 each (not surplus Telcom ones).
>> I grabbed two and they work.
>>
>> My antenna was a "hockey puck" style antenna sitting on the window
>> sash, facing South.
>>
>> 73, Dick, W1KSZ
>>
>> Sent from Outlook<http://aka.ms/weboutlook>
>> ________________________________
>> From: time-nuts <time-nuts-bounces at lists.febo.com> on behalf of Grant Hodgson <grant at ghengineering.co.uk>
>> Sent: Monday, February 4, 2019 11:15 AM
>> To: time-nuts at lists.febo.com
>> Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system
>>
>> Paul
>>
>> The keyword is GPSDO - GPS disciplined oscillator.  The vast majority of
>> these will give a 10MHz output.  The long term accuracy is the same as
>> the GPS navigation system, which for most purposes is similar to that of
>> national standards.  GPSDOs are more stable than most rubidium standards
>> in the long term, and GPSDOs are extremely common in most laboratories.
>>
>> The Trimble Thunderbolt is very common and available on the surplus
>> market, as is the HP Z3801A.  James Miller (G3RUH) used to sell an
>> excellent GPSDO.  There are other home-brew designs available if you
>> want to build.   These have all been extensively characterised if you
>> want the details.
>>
>> If you want to buy new, then there are products such as the Fury and
>> Firefly from Jackson Labs; , U-Blox have many offerings (not sure if
>> they do a GPSDO though).
>>
>> Google GPSDO or GPS frequency standard, or check the leapsecond.com
>> website for more information - there's loads out there, it's just a case
>> of using the right term in the search engine.
>>
>> regards
>> Grant
>>
>>> Date: Sun, 3 Feb 2019 23:43:10 -0000
>>> From: "Paul Bicknell" <paul at bicknells.f2s.com>
>>> To: "'Discussion of precise time and frequency measurement'"
>>>      <time-nuts at lists.febo.com>
>>> Subject: [time-nuts] 10 mhz accuracy for a satellite system
>>> Message-ID: <D1F28D64EDD440EC834753538090F381 at precision380>
>>> Content-Type: text/plain;     charset="iso-8859-1"
>>>
>>>
>>> Dear all
>>> I currently use a 198 Khz off air standard but I can no longer use  600 khz
>>> since it moved from Rugby
>>> I have herd a lot about varies frequency references that use satellites
>>> This technology has improved immensely & become more affordable over the
>>> past 5 years
>>>
>>> So can a standard locked to a satellite be as good as a Rubidium ?
>>>
>>> What accuracy can I achieve for a satellite system below ?800 as I am not
>>> familiar with the latest that are on offer?
>>>
>>> Regards Paul Bicknell  South Coast UK
>>>
>>>
>>
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>
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