Hi Tom,
Thank you for the comments. The results are better than my expectation.
Please find the new result with two Morion's OCXO: the first is an external
reference for CNT-91 and second - DUT.
Charles,
I have a machine-translated PDF (~2.5MB), but nowhere to put it
up. If you have web space for it, please feel free to do so
(assuming that Karen does not object).
I am OK with it if it might be interesting to someone...
Karen
Date: Mon, 03 Nov 2014 15:43:47 -0500
From: Charles
Hi,
yes, it is my fault - my set up (connections) for TI mode was not correct.
According your advices I went back to the frequency mode and set gate / sample
time to 1 second for CNT-91 and TimeLab.
Then I switched on Smart Frequency and Interpolator Calibration option on
CNT-91
1.
Charles, John and Bob,
Many thanks for your advices.
1) Charles Steinmetz wrote: I would suggest trying a few of the oscillators
again (no need to try them all), using the Isotemp OCXO as the time base for
the Pendulum by connecting it to the Pendulum's REF input and selecting
External
On Sun, 2 Nov 2014 12:13:34 +0300, you wrote:
Mode has been switch from Frequency to TI - result is much better now. It was
the main improvement in my measurement. Thanks a lot!
Picture of ADEV OCXO result -
Hi
The fact that the plots are still going down (as 1/tau) past the 1.0x10^-13
point at 1,000 seconds is also a pretty good indication that it's not really
ADEV of an OCXO.
The 100 ps rated single shot accuracy of the counter would give you 1.0 x10^-10
at 1 second and a 1/tau slope.
Bob
Karen wrote:
Mode has been switch from Frequency to TI - result is much better
now. It was the main improvement in my measurement.
Your plot shows all traces starting at ~1e-9 at 0.1 second and
dropping almost ruler-straight at 10x per decade.
Any real crystal oscillator will flatten out
Mode has been switch from Frequency to TI - result is much better now. It was
the main improvement in my measurement. Thanks a lot!
Picture of ADEV OCXO result -
https://dl.dropboxusercontent.com/u/21338179/hamradio/OCXO_Adev/OCXO%
20ADEV%20TI%20mode%2020141102.jpg
If you're taking a
John wrote:
It seems to me that it's just a case of expecting too much from a counter.
Possibly, but a well-tuned 5370B can get to the low e-12's at 1-10
seconds. It has better one-shot resolution than the Pendulum, but
not by a factor of 10. So, I'd have thought the Pendulum would at
csteinm...@yandex.com said:
Yes, using TI mode is essential for getting down to the counter's limits.
What's going on there? It's just a divide, right? Is the firmware not smart
enough to do get enough precision?
Do all counters have that problem?
--
These are my opinions. I hate spam.
It seems to me that it's just a case of expecting too much from a counter.
Possibly, but a well-tuned 5370B can get to the low e-12's at 1-10
seconds.
You can get down there with TI averaging, but the data you get is not ideal
since the averaging process smooths out the very instabilities
On Fri, 31 Oct 2014 23:40:04 -0400, you wrote:
John wrote:
It seems to me that it's just a case of expecting too much from a counter.
Possibly, but a well-tuned 5370B can get to the low e-12's at 1-10
seconds. It has better one-shot resolution than the Pendulum, but
not by a factor of 10.
Hal wrote:
Yes, using TI mode is essential for getting down to the counter's limits.
What's going on there? It's just a divide, right? Is the firmware not smart
enough to do get enough precision?
Do all counters have that problem?
The raw TI data have all of the benefit of the
John,
Thank you, done.
I saved all .TIM files for each OCXO to have an opportunity to compare all
variants off line.
I will publish the results shortly.
Karen
Date: Wed, 29 Oct 2014 13:43:51 -0700
From: John Miles j...@miles.io
Don't forget to hit 'f' and/or 'p' to check the frequency and
Alex,
Thank you for the advice.
I have a colleague in Moscow who has a big experience with MV89A repair.
73 de Karen, ra3apw
Date: Wed, 29 Oct 2014 14:57:17 -0700
From: Alexander Pummer alex...@ieee.org
Don't give up Karen, the Morion oxcos are relative easy to repair, you need
one
Thanks All for your comments and clarifications.
The next OCXOs have been tested today:
* Morion MV89A 10.000MHz #1
* Morion MV89A 10.000MHz #2
* Morion MV89A 10.000MHz #3
* Isotemp 131-191 10.000MHz #1
* Pilot C3Z 10.000MHz
* Bliley NV26R891
Karen wrote:
The next OCXOs have been tested today:
Did you test the oscillators free-running (NOT in your GPSDO)? If
so, those plots look much too high (by at least an order of
magnitude, maybe even 2 or more OOM for some of the oscillators).
Of course, oscillators take time to settle
Thank you, Charles.
All OCXOs have been tested in free-running mode after 40-50 min of
switch-on/warming.
All OCXOs have been installed in isolated close box to exclude external
airflow.
Cases of all OCXOs had not any contact with external metallic parts of the
box.
Karen
Karen wrote:
Karen wrote:
All OCXOs have been tested in free-running mode after 40-50 min of
switch-on/warming.
All OCXOs have been installed in isolated close box to exclude external
airflow.
Cases of all OCXOs had not any contact with external metallic parts of the
box.
Then it appears that something
Assuming that the test above (with the external REF) gives similar
results to what you posted today, there is something wrong with your
measurement setup. Are the input signals triggering the counter very
stably near the middle of their peak-to-peak voltages? Is the
counter adjusted to give
Hi
Unless the OCXO’s you have are broken, there is something wrong with your
measurement. I have bought enough broken OCXO’s to know that you can get quite
a few bad ones for every good one you find.
The CNT counters are good instruments. They will do about as well as any
frequency counter
Karen,
as by the datasheet, the time interval resolution of your counter is 50 ps.
This translates into an ADEV value of 5E-11 at tau = 1 sec, 5E-12 at tau
= 10 sec etc, and represents the theoretical measurement limit of the
counter.
It can be measured by feeding the same signal into both
Hi
The gotcha with translating ADEV directly to a measurement is the nature of
ADEV. You are looking at a standard deviation measure, so the result will be
some sort of “one sigma” kind of measure.
Bob
On Oct 30, 2014, at 6:32 PM, Adrian rfn...@arcor.de wrote:
Karen,
as by the
Thanks again for your explanations and advices.
I raised this question as a ADEV measurement result of my GPSDO/NEO-7M is about
1E-9 for tau = 1sec
http://www.ra3apw.ru/wp-content/uploads/2014/10/NEO7M_OCXO_MV89A_10M_2h0_ADEV.jpg
and it isn't meet my expectation.
In my understanding (before I
Karen wrote:
I raised this question as a ADEV measurement result of my
GPSDO/NEO-7M is about 1E-9 for tau = 1sec and it isn't meet my
expectation. In my understanding (before I published my question
here) the reason for this is not a good enough short range stability
of my frequency
Le 29 oct. 2014 à 08:32, Karen Tadevosyan a écrit :
Thanks again for your explanations and advices.
I raised this question as a ADEV measurement result of my GPSDO/NEO-7M is
about 1E-9 for tau = 1sec
http://www.ra3apw.ru/wp-content/uploads/2014/10/NEO7M_OCXO_MV89A_10M_2h0_ADEV.jpg
and it
Charles,
Thanks a lot for the detailed explanation and recipes. Understood and will
check this weekend.
All my Morion 10MHz MV89A OCXOs are used and from eBay's. That's why the first
version of broken surplus MV89A looks realistic.
Best regards,
Karen
Date: Wed, 29 Oct 2014 10:02:44 -0400
Charles,
Thanks a lot for the detailed explanation and recipes. Understood and will
check this weekend.
All my Morion 10MHz MV89A OCXOs are used and from eBay's. That's why the
first version of broken surplus MV89A looks realistic.
Best regards,
Karen
Don't forget to hit 'f' and/or 'p' to
Don't give up Karen, the Morion oxcos are relative easy to repair, you
need one coca-cola can, cut it is pieces until you get a very thin ALU
foil, get some thicker carton wind around the box of the OXCO's box that
way you have a heat isolation between the OXCO's box and the vise, which
you
Hi
Straight sawtooth corrected GPS starts out with (say) a 1x10^-9 ADEV at 1
second. That ADEV likely drops as 1/tau. If you go to 10 seconds it’s 1x10^-10.
Your Rb starts out with a (say) 1x10^-11 ADEV at 1 second. That ADEV likely
drops as 1/ square root (tau). If you go to 100 seconds it
Bert,
Thank you for the interesting GPSDO/FE5680A proposal. I will contact you off
list.
Karen, ra3apw
Date: Sun, 26 Oct 2014 17:22:45 -0400
From: ewkeh...@aol.com
Karen
To a large degree it depends on what you want to use it for. HP 5065 is
considered top of the line and PRS 10 is a
John,
Thank you for the links (I visited few times before) and your recommendations.
Really I am looking for a source with a good short range stability performance
between 1 and 10 seconds.
I will prepare additional description of my task with more details shortly ...
Special Thanks for your
Hi Charles:
The SRS PRS-10 is based on their 10 MHz SC-10 oscillator. This is what I installed in the Gibbs rack box and made use
of it's the power supplies and added down counters to get a 1 PPS output.
http://www.thinksrs.com/products/SC10.htm
There are options for phase noise and aging
Many thanks for all your recommendations.
Let me provide more details for understanding of my task.
I am playing with a GPSDO project on base of uBlox NEO-7M
(http://www.ra3apw.ru/ublox-neo-7m-ocxo-gpsdo/) - sorry, text in Russian.
One of the main step – ADEV measurement of a developed GPSDO.
Karen wrote:
Really I am looking for a source with a good short range
stability performance between 1 and 10 seconds.
I concur with everything Tom wrote. If that is your goal, the best
you are likely to do is with a good, free-running (non-disciplined)
OCXO. That will have the best
Karen,
a good double oven OCXO such as Morion etc will give you much better short
term stability than most Rudidiums can give you. By a factor of 10 or even
100 sometimes below 10s measurement interval.
The Rb's are better anywhere from 100s to many 1000 seconds.
bye,
Said
In a
Hello Karen,
I think you are confusing and/or mixing the terms stability and
accuracy with respect to your project.
It all depends upon your measurement period and the property being
measured. A GPSDO will never beat a truly, very high quality OCXO on a
short term basis in the stability
Hello All,
Can I have your recommendation regarding a choice of 10 MHz rubidium source
(available now on eBay like FE-5680; LPRO-101; LPFRS; FRS etc.) as a
reference signal for my frequency counter Pendulum CNT-91.
Thanks in advance.
Karen, ra3apw
---
Это сообщение свободно от
Karen,
PRS-10..
Sent From iPhone
On Oct 26, 2014, at 10:46, Karen Tadevosyan ra3...@mail.ru wrote:
Hello All,
Can I have your recommendation regarding a choice of 10 MHz rubidium source
(available now on eBay like FE-5680; LPRO-101; LPFRS; FRS etc.) as a
reference signal for my
I know what your next question will be, I see that these rubidium
oscillators all can be adjusted over a range that falls on both sides of
10MHz. What should I use as a calibration source to adjust my rubidium
oscillator? Then you think If I have this 10MHz calibration source, why
not just run
Karen
To a large degree it depends on what you want to use it for. HP 5065 is
considered top of the line and PRS 10 is a very nice Rb but lately I have seen
lamp oscillator failures. I like FRK, well documented easy to modify and
if done right super performance.
As part of a GPSDO project
Can I have your recommendation regarding a choice of 10 MHz rubidium source
(available now on eBay like FE-5680; LPRO-101; LPFRS; FRS etc.) as a
reference signal for my frequency counter Pendulum CNT-91.
You might take a look at the plots at http://www.ke5fx.com/rb.htm if you
haven't
Hi Karen:
The ones you mention are all stand alone Rb oscillators that need to be
calibrated to set their frequency.
This was the historical way that crystal oscillators were calibrated every year or so. The great advantage of Rb over
crystal oscillators is that their drift is specified in
Brooke,
One use for the R variants of the Fluke/Pendulum counters is/was for
calibrating base-stations. They had issues with ovens and turning the
counter to the side as you lifted it up. A rubidium inside solved that
in a nice way.
It's not all government work you know. :)
Cheers,
Magnus
I know what your next question will be, I see that these rubidium
oscillators all can be adjusted over a range that falls on both sides of
10MHz. What should I use as a calibration source to adjust my rubidium
oscillator? Then you think If I have this 10MHz calibration source, why
not just
Hi Magnus:
I've also heard that in order to calibrate rack mount crystal oscillators in instruments they need to be in the same
orientation as when mounted in the rack. So you can not remove the instrument from the rack and turn it on it's side
for the cal. So for some instruments that means
Hi Brooke,
I wonder which instruments that would be, as most of them calibrate
easily standing flat on the bench.
Cheers,
Magnus
On 10/26/2014 11:01 PM, Brooke Clarke wrote:
Hi Magnus:
I've also heard that in order to calibrate rack mount crystal
oscillators in instruments they need to be
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