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

Wed Feb 6 00:16:50 UTC 2019

Here's a shot of what's inside those T-Bolts I bought.
(thanks to tvb for reducing the size of my original).

Comments solicited ...

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 12:11 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 10 mhz accuracy for a satellite system

Hi

If the sticker on the OCXO (not the label on the outside of the box) has a date code
in 2006, that should be fine. I’ve seen cases on … errr … various sites … errr …
where the stuff inside the box did not match up very well with the labels on the outside
of the box. No idea why ….

Bob

> On Feb 5, 2019, at 12:26 PM, Richard Solomon <w1ksz at outlook.com> wrote:
>
> 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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