Guys,
I'm repairing a 1960's vintage lab-grade rubidium standard, General
Technology Corporation model 304-B. Apparently Tracor bought GTC soon
after this unit was made, because references to this as a "Tracor 304-B"
seem to be more common. I've made some progress, but now it seems like
time to
Love the graphic on the website.
The use of a Foucault Pendulum with Earth as the bob is inspired...
> -Original Message-
> From: time-nuts-boun...@febo.com
> [mailto:time-nuts-boun...@febo.com] On Behalf Of Steve Allen
> Sent: Monday, February 18, 2013 20:18
> To: time-nuts@febo.com
>
Corby,
On 18/02/13 20:59, cdel...@juno.com wrote:
Ok I've been plotting my oscillators for years using Allan Deviation.
That way all my records can be compared easily.
Is there any advantage to using Modified Allan Deviation?
It seems to give a better stability plot but that just seems to be
Hi Bob,
On 2/18/2013 6:19 PM, Bob Camp wrote:
Hi
The -Z3811 is indeed a part out of a HP GPSDO. HP is a big enough customer that
the part they get *may* have little relation to the standard part.
True, but it doesn't look like there were many Z3811s made. The order
wouldn't have been that
In late 2011 we held a meeting on the Future of UTC in Exton Pennsylvania.
The 400 pages of proceedings from the presentations at that meeting
have been published on paper and in electronic form.
The sequel to that meeting is planned for late May of this year.
Requirements for UTC and Civi
Hi,
Probably Elio will jump in and tell us more on this, but I must advice
that the unit where he did his forensic examination was a FE-5680A of
the 10 MHz fixed frequency output variety (not accounting for the small
adjustment margin)and also has a fixed 1 PPS. This unit doesn't have
the t
Hi Herbert,
Nice work ! A few comments that may help you in your quest. There are two
primary methodologies used in the FEI-5680A Rubidium.
It appears, from your picture, what you have is the older style that is analog
for control of the Rubidium frequency control loop. A VERY GOOD THING ! Wh
Hi
The -Z3811 is indeed a part out of a HP GPSDO. HP is a big enough customer that
the part they get *may* have little relation to the standard part.
If they all started out at the same temperature, then the noisy ones finish
warmup quicker than the quiet ones. Take a look at when the final "gl
I often plot both ADEV and MDEV, too. The difference between them indicates the
amount of white phase noise there is in the measurement (the sum of DUT and REF
and phase meter). You'll see for some standards, especially at longer tau,
there is little or no difference.
Right, MDEV is almost alw
In a message dated 18/02/2013 22:45:12 GMT Standard Time,
paulsw...@gmail.com writes:
Herbert
Thanks for the assembly listing. Someone else on time-nuts had done quite
the job of reverse engineering the schematics and other information. Seems
like the two of you could collaborate. Sorry do no
Hi Bob,
On 2/18/2013 2:42 PM, Bob Camp wrote:
Hi
Like any control loop, gain, bandwidth and noise are all related. In a DOCXO
you have two control loops and they do interact. That said, there's nothing
grossly wrong with the four OCXO's. The noisy parts have a bit more gain in the
controller
Hi
There's quite a bit less in the PIC code than I would have expected. If that's
everything that's there, the PIC does very little heavy lifting. Nice job on
the dis-assembly.
Many of the 10 MHz out FE Rb's are actually the 1 pps version that has been
converted to 10 MHz after the fact. The
Herbert
Thanks for the assembly listing. Someone else on time-nuts had done quite
the job of reverse engineering the schematics and other information. Seems
like the two of you could collaborate. Sorry do not recall the name.
Welcome to time-nuts.
Regards
Paul
WB8TSL
On Mon, Feb 18, 2013 at 4:32 P
I'm new to the time-nuts community, so I simply start
with a short info on how I got into this situation :)
(skip forward to if not interested)
Not long ago, I decided to build a reasonably good
frequency counter for my personal use and maybe if
the result is simple and elegant, I'll publish th
Hi
Like any control loop, gain, bandwidth and noise are all related. In a DOCXO
you have two control loops and they do interact. That said, there's nothing
grossly wrong with the four OCXO's. The noisy parts have a bit more gain in the
controller. The quiet parts have a bit less gain. The easy
It's not really noise, the feedback loop is marginally
stable. What you are seeing is how the stability changes
due to minor differences in the parts used in the loop,
and the thermal masses and insulation of the oven.
-Chuck Harris
Ed Palmer wrote:
I know that when making AC measurements on v
Ok I've been plotting my oscillators for years using Allan Deviation.
That way all my records can be compared easily.
Is there any advantage to using Modified Allan Deviation?
It seems to give a better stability plot but that just seems to be
cheating!
If I plot both ways what do the difference
I know that when making AC measurements on various OCXOs of the same
type, you have to expect wide variations in the results. e.g. TVB's
Allan Deviation measurements on a selection of 10811A oscillators at
http://www.leapsecond.com/pages/z3801a-osc . But what about DC current
measurements?
Bob,
Just wanted to let you know your advice to let the FRK run for a while was spot
on.
The lock voltage is down to 9.2 volts.
I was able to get my thunderbolt with the bad oscillator oven working by
heating the
oscillator with a power resistor. After it locked I could see on an
oscilloscope
That was the intent. Break/toss / we get to buy'em after a pile stacks up.
>From what I have run into peaking may or may not be the right answer is my
only real addition to the discussion.
The RF oscillator on the bulb peak if even tunable.
The hamonic multiplier. Peaking that could easily lead to
Hi
I think the truth of the matter is that these gizmos have been cheap enough
(and complicated enough) that they don't get repaired a lot. Certainly the VCXO
gets tweaked, and there are a couple of caps that explode / get replaced. Past
that either they don't break, or they get replaced.
Bob
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