Hi Beale,
From: beale be...@bealecorner.com
I assume dewar flasks are limited to aerospace applications.
:-) You keep your coffee hot in it!
Bye,
Jean-Louis Noel, OO1J
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Hi,
I have been looking at a similar problem. What I have found is:
many plastic foam materials have very low conduction but are
transparent to long wavelength radiation, so thermal heating/cooling
through them is mainly by thermal radiation.
If you wrap an item in plastic foam, then a
Eugene,
Welcome to the list and beware of how 'addicting' this can be. I started
out with your exact same purpose, minus all the equipment you have, and am
still a 'newbie'.
First question is do you want a 'primary' standard (in essence, one that
does not need to be calibrated) or a secondary
Bruce wrote:
http://www.rakon.com/Products/Public%20Documents/Specifications/RFPO40.pdf
The following US patent application may or may not be instructive:
Hi,
The fact they refer that atmospheric s/n degradation and dropouts etc
being replayed precisely lead me to think this is just a spectrum
rec/play machine (no mod/demod of any kind)
like the ham-oriented time machine but for GPS.
http://www.expandedspectrumsystems.com/prod2.html
Luis
I'm using the TAPR HPSDR - LPU linear power supply
to power a pair of Thunderbolts. It has switching
for the -12VDC, but the +12 and +5 are linear.
I didn't use the included ATX or PowerPole connectors,
but wired direct. It runs fine from my 13.6 VDC
house battery.
Mike - AA8K
On
beale wrote:
In an attempt to educate myself about temperature stability, I put a temperature
sensor in a 1 cube of brass wrapped in plastic packing-type bubble wrap, and
compared that with another sensor outside the bubble wrap, with the whole
combination in a thin nylon case just to slow
Luis Cupido wrote:
Hi,
The fact they refer that atmospheric s/n degradation and dropouts etc
being replayed precisely lead me to think this is just a spectrum
rec/play machine (no mod/demod of any kind)
like the ham-oriented time machine but for GPS.
But they mention software to generate sequences.
Hummm... right...
so I think we need to look inside one to be sure what it is...
lc
ct1dmk.
jimlux wrote:
Luis Cupido wrote:
Hi,
The fact they refer that atmospheric s/n degradation and dropouts etc
being replayed precisely lead me to
Thermos flasks were pretty common on early crystal oscillatots, including
GR, HP 107(?), and Sultzer at least.
-John
In an attempt to educate myself about temperature stability, I put a
temperature sensor in a 1 cube of brass wrapped in plastic packing-type
bubble wrap, and
Joe,
You are bust greasing an already slippery slope. :)
-John
==
Eugene,
Welcome to the list and beware of how 'addicting' this can be. I started
out with your exact same purpose, minus all the equipment you have, and am
still a 'newbie'.
First question is do you
Worse. Those books will start you thinking about home brew H MASERS. T^hey
make UHV seem doable.
-John
===
John Strong's Procedures in Experimental Physics has a section on
thermal design (for furnaces and ovens), and is worth having a copy of.'
Moore, et.al., building
did you have any luck?
On Tue, Nov 23, 2010 at 8:05 PM, paul swed paulsw...@gmail.com wrote:
Not a problem on spelling especially if tired.
The problem you are running into is really curious indeed.
Since we have no LORAN C in N A anymore. I can only use the loran simulator
to drive the
In message 4cefd115.5030...@earthlink.net, jimlux writes:
beale wrote:
What is done in real instruments that need good thermal insulation?
I assume dewar flasks are limited to aerospace applications.
One good allround foam material is Armaflex
--
Poul-Henning Kamp | UNIX since Zilog Zeus
Hi Eugene,
From your comments and equipment list I guess you are looking for low noise
and stability rather than absolute accuracy. In this case I'd go ro a 10811
OCXO. Check to make sure none of you existing equipment doesn't have one
already They were commonly fitted as high stab options. For
Well, my 8662A I believe has an 10811A in it. Hard for me to imagine that I
would be able to see this drift on the scope? But I've never thought about
it so maybe I need to think more! But I don't mind spending a bit of $ to
avoid the periodic scope-based calibration process to adjust. Although
Certainly in the 1 in 10E9 region a scope is fine.
Set the scope to trigger on the 1 PPS and look at your local 10 MHz at 10
or 20 nS/div. A storage or DSO scope makes this pretty easy. You can tweek
your local osc pretty quickly this way. At 10 nS/div a 1 in 10E9 walks 1
div in ten seconds.
Hi
My guess is the 1 bit DAC is nothing more than the FPGA output pin. About all
you really need is enough of a buffer to stay ahead of the USB bus. That may
not be much with a modern USB chip set and a hand made driver on the PC.
Bob
Sent from my iPhone
On Nov 26, 2010, at 10:34 AM, jimlux
Hi
The other answer is to let the temperature control electronics take care of the
problem. If you are doing something inside that uses energy (like an
oscillator) it have generate a heat rise through the insulation.
Bob
Sent from my iPhone
On Nov 26, 2010, at 2:24 AM, beale
Hi
First option would be to dig into what you already have. There may be a pretty
good OCXO in something on your bench.
Any TBolt with a date code past 2001 should have a good OCXO in it. It's plenty
good enough for what you are trying to do.
Bob
Sent from my iPhone
On Nov 25, 2010, at
One thing to be aware of with the LM35 type of sensors in the TO92 package is
that virtually all of the temperature input to the chip is via the leads (fine
print in the data sheet). I have seen several places with the device package
epoxied to some surface or embedded in some insulation with
On Fri, Nov 26, 2010 at 6:41 AM, Robert Darlington rdarling...@gmail.comwrote:
I keep it in a styrofoam beer cooler surrounded with bottled water in a
draft free area and it's been all over the map.
Robert-
Are you doing this for temperature stability? How stable is it?
Dave
Yes I agree a newer thunderbolt would surely suffice for me and probably also
the ocxo in my 8662A synth
But I am still academically curious about the impact of more channels of
satellites? What is the value of these extra sats?
Thanks!
On Fri, 26 Nov 2010 13:01:12 -0500, wrote:
Hi
First
I'm running another test now and it's significantly improved after the 48
hour survey. Before I'd see several degree swings over the course of an
hour, now it's more like 1.1 degrees in the last 8 hours. The problem here
is I didn't do anything to the styrofoam box, but the idea was to keep
Hi Eugene,
the extra channels usually come on more modern GPS receivers that also give
you sometimes much higher sensitivity, much faster lock time, less 1PPS
jitter, sometimes WAAS/SBAS capability, and last but not least more
redundancy and better performance in environments with
Hi:
A friend is looking for a low cost GPS receiver to set the clock in the
computer that controls his telescope mount. USB would be nice but is not
a requirement.
For example does eBay item 130456356506 set the computer clock?
This GPS receiver for the Nikon has a mini-USB connector, but when
Yes I agree a newer thunderbolt would surely suffice for me and probably
also the ocxo in my 8662A synth
But I am still academically curious about the impact of more channels of
satellites? What is the value of these extra sats?
Thanks!
In a mobile scenario, you need measurements to four or
-Ursprüngliche Nachricht-
Von: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] Im
Auftrag von bro...@pacific.net
Gesendet: Freitag, 26. November 2010 22:43
An: time-nuts@febo.com
Betreff: [time-nuts] USB Low Cost GPS Timing Receiver
Hi:
A friend is looking for a low cost
Brooke,
Google says the SD-200 speaks 4800 baud NMEA at 1 second intervals.
It is not clear whether the message is fixed of if it will reply
to queries.
Your question only concerned cost. Is one second accuracy adequate?
Bill Hawkins
-Original Message-
From: bro...@pacific.net
Sent:
namic...@gmail.com said:
Find some closed cell polyethylene that is quite thin and some very light
aluminium foil and you could make many layers.
How about aluminized Mylar?
If the many-reflective-layers idea really works, I'd expect somebody to sell
foam built that way. Why don't they?
--
That's what those golden thermal blankets are on spacecraft and in
cryostats. I'm not quite sure whether the golden color comes from a
deposited film of Au, or whether it's color comes from the Mylar. It's
more likely the former. I've seen the stuff up close, but have not worked
wit it personally.
Anyone have a different/later PICTIC II parts list (or from an alternate
supplier)?
Thanks,
Dave
On Fri, Aug 6, 2010 at 1:02 PM, Bob Camp li...@rtty.us wrote:
Hi
I believe the project at:
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=8736DCEE10
is up to date in (no
Ahh. Very interesting explanation. So is it somewhat correct to assume (yes,
I know) that for a stationary (non-mobile) environment, these extra sats
dont make much difference? This seems to be what the explanation is saying.
Ok. So let me see. For a frequency standard for use in lab equipment,
Hal Murray wrote:
namic...@gmail.com said:
Find some closed cell polyethylene that is quite thin and some very light
aluminium foil and you could make many layers.
How about aluminized Mylar?
If the many-reflective-layers idea really works, I'd expect somebody to sell
foam built that way.
Ahh. Very interesting explanation. So is it somewhat correct to assume
(yes,
I know) that for a stationary (non-mobile) environment, these extra sats
dont make much difference? This seems to be what the explanation is
saying.
Pretty much, although if your view of the satellites is obscured
J. Forster wrote:
That's what those golden thermal blankets are on spacecraft and in
cryostats. I'm not quite sure whether the golden color comes from a
deposited film of Au, or whether it's color comes from the Mylar. It's
more likely the former. I've seen the stuff up close, but have not
Hi
The gold color in a space thermal blanket is from - gold. The normal formula is
to use gold leaf and tissue paper (not quite the Kleenex variety, but similar)
in layers. The gold leaf is *very* good for IR reflection. The tissue paper is
porous enough that there's very little air trapped
W2HX wrote:
Ahh. Very interesting explanation. So is it somewhat correct to assume (yes,
I know) that for a stationary (non-mobile) environment, these extra sats
don’t make much difference? This seems to be what the explanation is saying.
Depends on your antenna location and type. The extra
Aren't the space blankets use in survival packs pretty much the same
stuff? The mylar-air space-mylar construction seems pretty rational, and
they are windproof.
-John
===
Hal Murray wrote:
namic...@gmail.com said:
Find some closed cell polyethylene that is quite thin and some
Not leaf in the ones I've seen. It's very clearly a metalized plastic
film. Gold leaf has virtually no structural strength. A breeze will tear
it. I also doubt any tissue paper usage.
Best,
-John
=
Hi
The gold color in a space thermal blanket is from - gold. The normal
I believe there is a reflective/foam insulator that is sold for setting
behind (what we in UK call ) CH radiators when the are mounted on outer
walls. That would meed Poul-Henning's temperature difference criteria, I
think. Interesting topic may me revise some 50 year old very rusty physics
:-))
Hi
In a decent location, with a good antenna, you can do just fine with an eight
channel receiver. In a poor enough location, a million correlators might indeed
improve things over a hundred thousand correlators.
Are you mounting your antenna outdoors?
Does it have a clear view of the sky?
Do
Hi
The ones I'm talking about aren't used anywhere there's air to create any
wind
Bob
On Nov 26, 2010, at 6:52 PM, J. Forster wrote:
Not leaf in the ones I've seen. It's very clearly a metalized plastic
film. Gold leaf has virtually no structural strength. A breeze will tear
it. I
bro...@pacific.net said:
A friend is looking for a low cost GPS receiver to set the clock in the
computer that controls his telescope mount. USB would be nice but is not a
requirement.
What sort of accuracy does your friend need?
For example does eBay item 130456356506 set the computer
Dont get the idea that radiation is only significant for large
temperature differences.
For two parallel surfaces at any distance apart the black body
radiation between them (around room temperature 300K) is near to 6
watts per square metre per degree (C*) of temperature difference.
That
In a message dated 26/11/2010 23:31:32 GMT Standard Time, w...@w2hx.com
writes:
Ahh. Very interesting explanation. So is it somewhat correct to assume
(yes,
I know) that for a stationary (non-mobile) environment, these extra sats
don’t make much difference? This seems to be what the
Hi Bill:
The telescope has around arc second pointing capability so I think he
needs a hundredth of a second or slightly better.
What's now done is to manually bring the scope onto a half dozen known
stars (called a short run) which sets time in the tracking software.
But if the tracking
Hi
A stand alone OCXO is good for telling you that where you are today is close to
where you were yesterday. It's pretty much useless for telling you weather
either of those places are the correct place to be. The GPS gizmo will do a
pretty good job of telling you that where you are is indeed
Some of the older GPSs had the 9 pin COM port connectors to interface with
the mapping SW running on a PC laptop (Magellen or Garmin ?). Might that
data stream contain good enough timing info? I don't knoe what protrocol
they used.
-John
===
Hi Bill:
The telescope has around arc
Not necessarily so..
My HP Z3815A here (desktop unit) has horrible phase noise and massive
spurs. Really to cry over since I know what the internal OCXO (1938A type) is
capable of generating.
See the attached plot.
bye,
Said
In a message dated 11/26/2010 16:37:26 Pacific Standard
Hi
Put another way:
If you set up / sync up a time source based on a cheap 1 ppm TCXO, you are good
for more than 10,000 seconds after the sync. If your viewing period is in the 2
to 4 hour range, it should work out pretty well.
Bob
On Nov 26, 2010, at 7:58 PM, Brooke Clarke wrote:
Hi
Bob Camp wrote:
Hi
The gold color in a space thermal blanket is from - gold. The normal formula is to use gold leaf and tissue paper (not quite the Kleenex variety, but similar) in layers. The gold leaf is *very* good for IR reflection. The tissue paper is porous enough that there's very
Bob Camp wrote:
Hi
The ones I'm talking about aren't used anywhere there's air to create any
wind
Bob
yeah, but there's plenty of handling and air currents before it gets
launched...grin
These days, I'd vote for evaporated metal on some substrate.
I'm virtually certain by 1968 they were using some plastic film. Maybe
Mylar, maybe Kapton, but metalized plastic. I was doing optics and
telemetry so was not really involved in other areas, but I babysat our
payload on that bird first bird for 5 months
-John
Bob Camp wrote:
Hi
Hi
It's a fused fiber material, more like the stuff they make overnight shipping
envelopes out of than a normal paper. It looks and feels more like tissue paper
than anything else though. The same outgassing and particles floating around
issues mess up the gaps in the sandwich. There are
Those switch mode regulator modules under the finned heatsinks in the
Z3815A are likely responsible for most of the spurs.
The ECL/CML logic dividers and the various ouputs like 19.6608MHz also
contribute.
Since the E1938A output is only +4dBm, its very easy to degrade the
phase noise in the
In message 013e01cb8dc6$41b038a0$4001a...@lark, Alan Melia writes:
I believe there is a reflective/foam insulator that is sold for setting
behind (what we in UK call ) CH radiators when the are mounted on outer
walls. That would meed Poul-Henning's temperature difference criteria, I
think.
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