Hi Bob and time-nuts,
thank you for your infos. It seems not to be an easy job to get a used
cesium clock in a good shape
with some reserve for a good few years of lamp live and an adaquate price.
The ones on the market are either for parts or like the both examples at
...bay fakes which costs
a lot of money and the not so experienced users are getting into a
bigger lot of problems...
The other crux with this clocks is oviously that they need to let them
running all the time for reaching
the better stability and exactness what the should have as as a
reference in the lab.
Bob your pricing info for an exchange of the cesium tube seems to be not
the right direction for the hobby
electronics user like me. I think it is a good idea not to buy such a
clock at the moment.
But the problem of mine and my be a lot of electronic developer and
scientists is that they cannot have their
reference systems running all the time. It must be possible to build a
reference which does not need weeks
to reach its best exactness and stability within hours...
Is there a known solution available which allows good short time
stability and also exactness which will be reached
within a maximum of one hour after power on?
My thoughts are going into the world of the well known GPSDOs with a
good OCXO inside and a precise Timing GPS receiver
module like UBlox NEO-M8P or a Furuno GT-87xx, a high precision roof
antenna with a good view of the sky, and one of
the best rubidium oscillators such a SRS PRS10...
This combination must do the trick. It should be not to hard to feed the
pps signal from the GPS receiver into the PRS10.
I read that the developer from SRS implemented the regulation software
loop for that into the firmware of the Rubidium
oscillator. With saving the states of the gps and the rubidium in two
separate real time clocks (battery buffered) and a
few lines of software for the microcontroller to arrange all with a
display must be enough.
I would be lucky if you guys could give me some tips about that or
alternatives to get such a stable reference with a short
avalability timeframe for locking and stabilisating.
Are there may be ready useable open hardware sources available?
Thank you guys in advance for all your help...
--
with best Regards
Chris
Am 03.02.2019 um 23:34 schrieb Bob kb8tq:
Hi
The gotcha with a Cs is the tubes wear out. Last time I put a tube in a 5071 it
cost just
about $40,000 including custom shipping of the “hazardous” Cs. From the
description
on that uint it does not *appear* that things are working correctly.
Even if you do get a working Cs standard, the question is - how much longer
will the
tube last? It might be good for another 10 years. It might die tomorrow. That
tends to be
a bit of a concern as far as running them all the time in a basement lab.
With the high performance tubes in the 5071, my experience was that 6 to 7
years of
continuous use was about it. The “standard” tubes in the 5071 should be good for
> 2X that
time period.
None of this is to say that the *only* reason one fails is the tube. It is not
at all uncommon
to have other stuff fail. Usually the small stuff gets fixed and they go back
into service.
When the tubes go (or the problem is complicated) the go on the market…..
Indeed none of this is to say you *can’t* get a working Cs. You most certainly
can. This
list is one pretty good place to find a working one from somebody who *knows*
that it is
running properly. I’m not selling any of mine, but you may see emails from
people who are.
Of course it there *was* a really good deal on a 5071 … hmmm …. maybe I need
another Cs …. :)
Bob
On Feb 3, 2019, at 5:16 PM, Christoph Kopetzky <c...@cksd.de> wrote:
Hi Bob,
thank you.
Wow I did not realize that. Very interesting :)
B.t.w. there is a HP 5071A on ...bay item nr 263497171568. Is this cesium clock
ok for buying?
--
with best Regards
Chris
Am 03.02.2019 um 21:29 schrieb Bob kb8tq:
Hi
The key is the top view of the 5065a. You can see through the holes in the top
of the unit.
There’s a big empty space to the right in the picture where the optical unit /
physics package
should be. There also are a few other tidbits missing but the physics package
is the biggie.
Bob
On Feb 3, 2019, at 2:30 PM, Christoph Kopetzky <c...@cksd.de> wrote:
Hello Corby,
in the case that this is a stupid question... I am sorry but can you tell me
how I can see that the optical unit is missing?
There are no pics of an open 5061A device...
I am also wondering why this seller is shipping these units for this
extraordinary price.
He is telling in the description that the shipping costs will be calculated at
the real destination but I will bet that the click
on the buy it now button bounds you to pay the whole sum ...
--
with best Regards
Chris
Am 03.02.2019 um 18:21 schrieb cdel...@juno.com:
Hi,
Wanted to warn about the 5065A that has now sold twice on eBay. (Jan 18
and Feb 2) When it first listed I contacted the seller and told him the
optical unit was missing (A12) and he should not call it "fully
functional" Anyway he sold it for his asking price and now it looks like
he just sold it again. If he has it returned and lists it again just be
aware its not all there! Not really worth the price with no A12!
Cheers,
Corby
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