Paul,
That's what I needed to know. Thank you very much. I'll let you
know how it goes.
Burt, K6OQK
From: Ziggy
Burt -
On the scope I see 950mv RMS with 50 ohm termination, 1.5V RMS with
1M. This is on a 9390-6000 OCXO with the default timing output
configuration, 10MHz on J7. Hope
OCXO not, but the little XO that drives the GPS, that you can be sure of it.
Didier
Sent from my Droid Razr 4G LTE wireless tracker.
-Original Message-
From: Bob Camp
To: Discussion of precise time and frequency measurement
Sent: Sun, 16 Dec 2012 8:08 PM
Subject: Re: [time-nuts] Z380
Hi Bob,
Herein lies the problem. The MV89 you linked to on eBay is a Dash-A part, so
the lowest stability one.. Hard to get the more stable ones.
Also, I am not looking for a single unit from EBay, I'm interested in sustained
production/reasonable pricing. Morion is very hard to deal with, and
Hi
… and what I'm trying to say also comes from the real world...
If you start putting "stuff" on an OCXO, be careful about the case temperature
and how the OCXO is spec'd. A few mm of dead air can make a good insulator.
That can boost the case temp quite a bit.
Bob
On Dec 16, 2012, at 9:06 PM
Hi
The sort of thermal randomness that turbulence is going to create at fan speeds
isn't going to come through the thermal mass of an OCXO to any great degree.
Bob
On Dec 16, 2012, at 9:05 PM, shali...@gmail.com wrote:
> Forced air will generally be turbulent, which means that the air speed an
On 12/17/2012 02:47 AM, Bob Camp wrote:
Hi
The gotcha here is that an un-cooled piece of gear will heat up and cool down as it's
work load changes. There is no "magic bullet" that keeps the temperature
constant with zero airflow in a normal design. Yes, I'm old enough to remember oil cooled
Hi
First order immune due to the OCXO. You still have the RF stuff hanging out
there in what ever breeze comes along. The OCXO does indeed change a bit if you
go from still air to a raging blast. Not as much as a TCXO, but there is a
shift.
Bob
On Dec 16, 2012, at 8:56 PM, shali...@gmail.com
Forced air will generally be turbulent, which means that the air speed and
pressure at any point will follow a somewhat normal (or not) random
distribution. That is not good for something that needs stable cooling. Air
flow resulting from convection cooling on the other hand is usually laminar,
One more thing the Thunderbolt is essentially immune from since there is no
separate XO for the GPS receiver which runs from the OCXO.
Didier
Sent from my Droid Razr 4G LTE wireless tracker.
-Original Message-
From: Said Jackson
To: Discussion of precise time and frequency measuremen
Hi
The gotcha here is that an un-cooled piece of gear will heat up and cool down
as it's work load changes. There is no "magic bullet" that keeps the
temperature constant with zero airflow in a normal design. Yes, I'm old enough
to remember oil cooled computers. Still no constant temperature a
On 12/17/2012 02:21 AM, Bob Camp wrote:
Hi
When you blow on a TCXO you are setting up variable airflow. A fan produces a
constant airflow. A variable flow gives you a variable temperature. A constant
flow keeps things pretty uniform.
Environnemental chambers have pretty massive airflow. TCXO'
Hi
Well here's a few examples:
HP10811 is a single oven. It's spec'd at 4 ppb over -55 to +71C. It's certainly
a common eBay item. It's also what's in a 3805A.
http://www.hparchive.com/Manuals/HP-10811AB-Manual.pdf on page 3
The Morion DOCXO's on eBay are available at 0.2 ppb p-p -20 to +70C.
Said,
On 12/17/2012 02:16 AM, Said Jackson wrote:
One item I forgot to mention:
One of the most airflow sensitive parts inside a GPSDO is the tcxo used on the
GPS receiver. Some GPS don't even use a tcxo, just an XO. They shall remain
unnamed.
Just lightly blowing on an M12+ GPS will make it
Hi
When you blow on a TCXO you are setting up variable airflow. A fan produces a
constant airflow. A variable flow gives you a variable temperature. A constant
flow keeps things pretty uniform.
Environnemental chambers have pretty massive airflow. TCXO's and OCXO's do
quite well inside them.
One item I forgot to mention:
One of the most airflow sensitive parts inside a GPSDO is the tcxo used on the
GPS receiver. Some GPS don't even use a tcxo, just an XO. They shall remain
unnamed.
Just lightly blowing on an M12+ GPS will make it lose lock immediatly.
This is easy to try for time
Bob,
We agree that Ocxos get real bad real fast if overheated. Not a problem in the
Z3805A box when run on a desk without clogging the vent holes, which is how
this thread started (do I need a fan for my Z3805A...)
Your stability numbers are very optimistic. There are very few single oven
Ocxo
Hi
Ok where to start.
Some typical numbers:
A DOCXO likely will be specified at around 0.3 ppb peak to peak over -30 to
+70C. That comes out to 0.003 ppb per degree. A single OCOX likely will be
specified at around 10 ppb peak to peak over -30 to +70C. That's 0.1 ppb per
degree. Yes, there ar
Hi Volker,
You are correct on that.
Bob is right in that thermal sensitivity is measured in a thermal chamber with
constant airflow at a very constant rate and temperature. While this works, it
is also somewhat unrealistic because who is going to set up a thermal chamber
for their ocxo in the
On 12/16/2012 05:40 PM, Graham / KE9H wrote:
In addition to knowing where the GSM cell site is, you time stamp the
time of arrival of a
specific feature in the cellphone signalling system. If the cellphone is
heard by three
(or more) cell sites, then you can calculate the location of the
cellphon
Indeed? I didn't expect that. There are people who say, that the control
loop of OCXOs is optimized for still air and no additional cooling at all.
Said told us, that...
>...a fan is about the worst thing you can do for your Z3805 it will
significantly worsen the stability of the output frequ
On 12/15/2012 9:38 PM, Hal Murray wrote:
GSM cell sites in the US have GPS because it is required to support E911
positioning. I'm not sure if it is used for anything other than this, but
it doesn't have to be.
So it's cheaper to install and maintain GPS rather than make one measurement
and tel
This is a rehash with better organization and more links of my side of a
discussion here.
http://www.ecnmag.com/blogs/2012/12/exploring-potential-watch-crystals
And for those who intend to comment on the "mystery list" the last line (not
counting philosophy and contact info):
The above is in
Hi
By far the most common way to test and certify OCXO's is in moving air. It's
rare to see one get in trouble from to much ventilation. The more common
problem is thermal runaway due to inadequate ventilation.
Bob
On Dec 16, 2012, at 7:57 AM, Volker Esper wrote:
>
> Steward,
>
> What is
It's the same as with the SR620 TIC. As long as you have only one common
chamber for all parts, you have to make tradeoffs for everyone:
the power supply needs cooling (as much as it can get), the control loop
of the oven is not designed for additional cooling, and comparators and
further elec
Steward,
What is the intended and what is the actual supply voltage? Which
current is the unit consuming?
When we know that, we can compare the power consumption with our units.
If it is in the same range, it should - with a little luck - be working
properly.
My two units are intended to be
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