I received one of these thunderbolts. It seems to work (currently
handicapped by an inadequate antenna) and is labelled P/N 48050-61 D/C
0331 on the outside.
The firmware is 3.00 and the OCXO labelled 37265 10.00 MHz B11859-17495
0310.
On Sat, Sep 12, 2020 at 10:43 PM Adrian Godwin wrote:
Hal Murray writes:
>
> p...@phk.freebsd.dk said:
> > I later talked to a geologist who knows the Danish underground well, and he
> > estimated I would have needed to drill to at least 25m depth to escape
> > seasonal temperature-changes and cited a research paper from the 1950'ies
> >
I used special order PVC Pipe with end caps, used the drilling mud to encase it
in the ground. The top cap had a U made up of PVC L's and was removable.
Initial tests where without any filling. Once convinced it worked I filled the
pipe with coin bags my local banker got me. Very strong canvas.
p...@phk.freebsd.dk said:
> I later talked to a geologist who knows the Danish underground well, and he
> estimated I would have needed to drill to at least 25m depth to escape
> seasonal temperature-changes and cited a research paper from the 1950'ies
> where the did precisely that experiment.
shouldbe q931 writes:
> > Apart from the entire "get electronics wet" thing, water would have
> > been near perfect.
>
> There are alternatives to water...
> https://www.3m.co.uk/3M/en_GB/novec-uk/applications/immersion-cooling/
For very, very specific use-cases, yes.
I have hard time
On Mon, Sep 14, 2020 at 10:36 AM Poul-Henning Kamp wrote:
>
>
> Matthias Welwarsky writes:
>
> > > The point is that there is no need to compensate the part while it is
> > > locked.
> >
> > It depends. For short time constants, yes, likely the control loop is able
> > to
> > follow the
ew via time-nuts writes:
> In 1973 I moved for TI to Dallas and had a 20 foot hole drilled to place my
> Sulzer One alternate.. Today I monitor my lab closely to better understand
> what to do. The monitor is placed on the top of the HP5065A[...]
When we built our new house I wanted to
Hi
> On Sep 14, 2020, at 3:59 AM, Matthias Welwarsky
> wrote:
>
> On Sonntag, 13. September 2020 15:05:36 CEST Bob kb8tq wrote:
>> Hi
>>
>> The point is that there is no need to compensate the part while it is
>> locked.
>
> It depends. For short time constants, yes, likely the control
Matthias Welwarsky writes:
> > The point is that there is no need to compensate the part while it is
> > locked.
>
> It depends. For short time constants, yes, likely the control loop is able to
> follow the temperature-induced drift of the OCXO. But you might want the TC
> to
> be as
Hi
Ok so you have a step change in temperature of say 2C over 5 seconds. What
(might) happen:
(Yes this is all a bit contrived, but it *is* the sort of thing that’s going on
in the TBolt). The units
shown are “Bob Units” :). They have no particular relation to LSB’s or to
PPT’s.
At 18
Bob kb8tq writes:
> The point is that there is no need to compensate the part while it is locked.
> It meets all the specs required of it by virtue of the lock to GPS. The big
> issue
> on these devices ( = cell tower GPSDO’s) is holdover. That’s where all the
> magic comes in.
>
>
Hi
Not done that way in this case. Keep in mind that the “stock” configuration
only runs a loop time
constant in the 10’s of seconds.
On the TBolt, the main source of temperature error is the DAC. Tossing a bit
more “stuff” at that
part of the design would have been higher on the list than
time-n...@welwarsky.de said:
> That is interesting, why wouldn't they use the information if it's available?
> Watching the temperature gives you a prediction of what is going to happen,
> while watching the phase only shows what has already happened. And knowing
> what's about to happen is
But doesn't the compensation help generate a feed-forward term, a way to
make the integrator better managed ?
On Sun, Sep 13, 2020 at 2:31 PM Bob kb8tq wrote:
> Hi
>
> The point is that there is no need to compensate the part while it is
> locked.
> It meets all the specs required of it by
Hi
The point is that there is no need to compensate the part while it is locked.
It meets all the specs required of it by virtue of the lock to GPS. The big
issue
on these devices ( = cell tower GPSDO’s) is holdover. That’s where all the
magic comes in.
Indeed, trying to compensate *and*
On Samstag, 12. September 2020 23:53:39 CEST Bob kb8tq wrote:
> Hi
>
> As far as anybody knows (which *is* a big qualifier indeed ….), the TBolt
> family only does it’s “temperature compensation” stuff when it’s in
> holdover. While it’s locked, there *appears* to be no compensation being
> done.
Hi
The unit you most commonly see is a version done for E911 cell tower upgrades.
It was an intermediate step to add that functionality before it could be done
internal
to the cell base station. Once the “real” solution came along, the E911 boxes
became
scrap. They went off to China to be
Thanks!
The one I've seen pictured most often comes in a (I think) slightly lower
gold-coloured (alocromed) case.
e.g. http://www.sydneystormcity.com/TrimbleThunderboltGPS.jpg
Is that any different ?
I did order the one from my link so will report on any markings. The vendor
mentioned part
Hi
As far as anybody knows (which *is* a big qualifier indeed ….), the TBolt
family only
does it’s “temperature compensation” stuff when it’s in holdover. While it’s
locked, there
*appears* to be no compensation being done. If it’s doing anything while
locked, it’s
learning what the TC is, so
Kevin,
Can you post your Lady Heather config file and command line options that
created that image ?
George
On 9/10/2020 19:08, Kevin Schuchmann wrote:
Guess my image didn't make it, I will add it as an attachment this time.
Swapped power supplies no difference.
Antenna is on a splitter
Kevin,
how long has it been in storage? I expect the GPSDO doing quite clever things
to compensate for temperature effects. There may be some parameters stored on
the device and the characteristics of the OCXO may have changed after being
turned off for an extended period.
Regards,
Matthias
Hi
The unit your link points to *is* the “classic” TBolt that showed up in volume
a bit
over a decade ago. That one is packaged with a (noisy) switching power supply.
There is no easy way to tell what era it is from. Indeed if it is from the
1990’s the
OCXO will not be quite as good as
I've been looking for a thunderbolt for a while, mostly because they're
such a benchmark within this group. I missed the period when they were more
commonly available and have mostly found ones that were a lot more
expensive, or had a large delivery cost due to being in Australia.
Some cheaper
Matthias,
You are correct, having spent hours looking at all the stable areas
and cooling and heating the gpsdo I find that when it reports that it is
116.25 F then it is stable.
So now I guess I need to figure out why it is so picky. I will measure
the current draw from a cold start and
On Freitag, 11. September 2020 01:08:09 CEST Kevin Schuchmann wrote:
> Guess my image didn't make it, I will add it as an attachment this time.
The temperature curve seems to show some correlation to what is happening with
the DAC. Seems that the DAC and OSC jumps are mostly during periods of
Hi
A couple things to check:
1) Is your power supply doing odd things? It’s the first thing I’d suspect in
this case.
2) Does the OCXO “behave” if you turn off the GPS ( = disconnect the antenna )
and watch
it with a counter?
3) While the antenna is disconnected from the TBolt, hook it to
Newbie here looking for comments from people with more experience with
thunderbolt E's to comment on what I am seeing.
Unit is jumping and ramping the DAC one direction then goes stable for a
bit only to start jumping and ramping the other way.
Oscillator heading south or more likely the
From: Chris Burford
To: Time Nuts Listings
Subject: [time-nuts] Thunderbolt E
Message-ID: <9165f782-88f7-d015-6a82-6102a4258...@austin.rr.com>
Content-Type: text/plain; charset=utf-8; format=flowed
I'm on the fence on purchasing a new Thunderbolt E from Trimble and
wanted to hear from curr
tings
Subject: [time-nuts] Thunderbolt E
Message-ID: <9165f782-88f7-d015-6a82-6102a4258...@austin.rr.com>
Content-Type: text/plain; charset=utf-8; format=flowed
I'm on the fence on purchasing a new Thunderbolt E from Trimble and
wanted to hear from current or past owners.
I have a couple of
I'm not going to buy one, but . . . what does a new-from-Trimble
Thunderbolt E cost?
Steve, K8JQ
On 7/11/2019 6:06 PM, Bob kb8tq wrote:
Hi
There is nothing on the spec sheet that leaps out as “obviously better” than the
T-Bolt’s that we all know and love. Indeed you *will* get support, a
Hi
There is nothing on the spec sheet that leaps out as “obviously better” than
the
T-Bolt’s that we all know and love. Indeed you *will* get support, a warranty,
and
a unit that has 10 to 20 years less wear and tear.
Bob
> On Jul 11, 2019, at 3:22 PM, Chris Burford wrote:
>
> I'm on the
I'm on the fence on purchasing a new Thunderbolt E from Trimble and
wanted to hear from current or past owners.
I have a couple of the eBay x-telecom patchwork quilt GPSDO units which
seem to do an OK job. Is there anything else besides a warranty and
better performance specs that the
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