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

Wed Feb 6 01:17:20 UTC 2019

Hi

That’s an odd one. It is very unclear *where* that OCXO came from. 

Bob

> On Feb 5, 2019, at 7:16 PM, Richard Solomon <w1ksz at outlook.com> wrote:
> 
> 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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