You'll need somwhat more than +14V for a generic 7812 to regulate
correctly.
Also, remember the local (to the regulators) decoupling caps, or some of
them make quite good HF oscilators!
See the data sheets for the particular regulators used for exact
details.
Dave B.
-Original
Mark Sims wrote:
99.95 ns is a typical number for the period reading at minimum gate time. Set
the gate time to 1 sec. My 5370A shows 99.999 999 9650 +/- 50 at 1 sec gate
time.
Measuring it's own time-base is expected to give value not exactly
on-beat. Internal cross-talk with the
At 12:44 AM 3/10/2010, Ed Palmer wrote...
It would seem to make more sense to have the fan blowing hot air out
the back and drawing the hot inside air over the temperature sensor.
The reason to have a fan blow in is so you can put a filter on it. It
also creates more turbulence inside the
Hi
Yes indeed, the period was measured with the two channels in the com mode and
the reference into one of them. I hadn't considered the trigger offset issues
and was expecting something sub-100 ps rather than 500 ps. Obviously I need to
spend some quality time with this beast. Now I gotta
Good point about the filter, but it doesn't appear that the 5371a or
5372a ever had a filter. Unless it was just done out of habit because
other HP units did have a filter.
Ed
Mike S wrote:
At 12:44 AM 3/10/2010, Ed Palmer wrote...
It would seem to make more sense to have the fan blowing
Mike S wrote:
At 12:44 AM 3/10/2010, Ed Palmer wrote...
It would seem to make more sense to have the fan blowing hot air out
the back and drawing the hot inside air over the temperature sensor.
The reason to have a fan blow in is so you can put a filter on it. It
also creates more
Hi everyone,
Keep on having that HP 5370A/B conversation! I just purchased a 5370A and will
take possession this weekend. Will probably have questions next week.
Thanks,
Bert, VE2ZAZ
__
The new Internet Explorer® 8 -
Ed Palmer wrote:
Good point about the filter, but it doesn't appear that the 5371a or
5372a ever had a filter. Unless it was just done out of habit because
other HP units did have a filter.
If you want to toss a filter on it because your environment isn't
exactly clean, it is trivial. Maybe
Bob Camp wrote:
Hi
Yes indeed, the period was measured with the two channels in the com mode and
the reference
into one of them. I hadn't considered the trigger offset issues and was
expecting something
sub-100 ps rather than 500 ps. Obviously I need to spend some quality time
with this
John and Said,
from my limited understanding of things I would have guessed that the
ADF4001/2 PFD's ability to produce very short pulses in the locked condition
puts a lot of energy into higher harmonics of the PFD's output, making it
more easy for the loop filter to remove them. In contrast to
Hello Group members,
I need some help interpreting Lady Heather software results like the colours
and chart results for My Tibold GPS Receiver, any help would be appreciated as
I am new at this.
Best regards,
Sal C. Cornacchia
Electronic RF Microwave Engineer (Ret.)
Hi Jim,
jimlux wrote:
This, and similar impressive accomplishments, has prompted some
lunchtime discussion at work (JPL).. One of us (N5BF) has been
contemplating what it would take to do an amateur EarthVenusEarth (after
some of his experiments doing EME with 5 watts)..
Has recently been
Yes, I replace the standard HP fan with a MUCH quieter one. I get mine from
a local surplus shop. It is made by AAVID. it draws 120 mA at 12V and I run
it off the 10V supply (which is somewhat over 10V).
I don't have one handy to get the part number. They also have a 160 mA model
At 4:10 PM + 3/10/10, Mark Sims wrote:
Yes, I replace the standard HP fan with a MUCH quieter one. I get
mine from a local surplus shop. It is made by AAVID. it draws 120
mA at 12V and I run it off the 10V supply (which is somewhat over
10V).
Before getting all whiny about
Ed,
From your description of the fan noise, I have one concern.
If the fan speed seems to increase without a good cleaning
or change in the supply voltage, then it's likely that the airflow
has been decreased, an obvious speed up is not good news.
Pete Rawson
On Mar 9, 2010, at 10:44 PM, Ed
Hi Tom:
I've built it and it works great. See:
http://www.prc68.com/I/Loop.shtml#K5JHF
Next is to develop a better loop antenna based on the Russian Ferrite rods.
---and---
The subject of my prior post, add thermal mass and insulation to the
32768 crystal.
Have Fun,
Next
This not your
Are you sure that it has a variable speed fan? My 5372A has a pretty quiet
fan and I have never tried to change it. I am assuming that it uses the same
117V fan as the 5371A. That thermal switch may be a power supply shutdown.
I have a couple of 5371A's that are a different matter.
Yes, the fan is variable speed and it's 12V DC. It's described in the
motherboard section of the service manual on page 11-4 (pdf page 503).
That's why I thought it was so odd that the fan is blowing cool outside
air over the thermal sensor on the motherboard. I guess they could have
Hi
Right now my main concern is if the gizmo is broken beyond repair. Setting
trigger levels manually will be possible on the two main inputs. Not so much
on the external arm input. Going through a full calibration on the
interpolators - pretty major effort.
First up on the project list is
Ed Palmer wrote:
One trick I always use to quiet down a rowdy fan is to replace the
mounting screws with rubber mounts. This isolates the fan's mechanical
vibrations from the chassis. The difference is audible - even with a
good fan. I salvaged some mounts from IBM machines that work
Hi
Fanless Atom motherboard / solid state disk / wall wart power supply ... DVD
is still the main source of noise.
Of course the bean grinder in the single cup Cappuccino machine drowns out
the DVD pretty effectively.
Looks like a 5370B with an intact front panel and
back to the original issue front panel
One thing I have had success with is emailing some of the
bigger EBay instrument sellers and asking if they have
a parts unit. It helps of you are/were a regular customer.
I repaired a 3325A that needed some buttons, a bottom panel
etc. I asked and was
Hi Ulrich,
I think in our design the spec is limited by the ~-100dBc noise at 100Hz
offset of the 100MHz VCXO.
Please note that the ADF4002 actually improves that noise by about 15dB
from the datasheet spec (or the unit we tested was that much better than the
one shown in the datasheet).
Bob Camp wrote:
Hi
Fanless Atom motherboard / solid state disk / wall wart power supply ... DVD
is still the main source of noise.
This was far from that. It is a AMD PHENOM II X4 90SE 2,5GHz CPU with 8
SAMSUNG ECOGREEN F2 1,5TB SATA disks is certainly not tailored in such a
fashion. The
Hello Group members,
I need some help interpreting Lady Heather software results like the colours
and chart results for My Tbold GPS Receiver, any help would be appreciated as I
am new at this.
Best regards,
Sal C. Cornacchia
Electronic RF Microwave Engineer (Ret.)
Hi Mathew:
There are a bunch of them, but I like the DS3231 because it has a
software frequency tweak and I2C interface.
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4627/t/al
http://datasheets.maxim-ic.com/en/ds/DS3231.pdf
Hi Bruce:
Do you have a value for the thermal resistance of
Hi Bruce:
What does m2K/W mean? See:
http://building.dow.com/europe/uk/proddata/styrofoam/thermal.htm
50 mm it's about 1.5 and for 100 mm it's about 3.
Have Fun,
Brooke Clarke
http://www.PRC68.com
Bruce Griffiths wrote:
Bruce Griffiths wrote:
Brooke Clarke wrote:
Hi:
For some time I've
~3.3E-2 W/mK.
If, as I suspect, its transparent to 10-20um infrared then adding
intermediate aluminium foil radiation shields may be useful.
Some styrofoam insulating panels include carbon black to inhibit
infrared transmission:
Thermal resistance is measured in degrees (C or K or ..) per watt.
Its inversely proportional to area and proportional to thickness.
I think the clueless clown who created that table means that for a 1
square meter panel of the specified thickness the thermal resistance is
the tabulated value
This, and similar impressive accomplishments, has prompted some
lunchtime discussion at work (JPL).. One of us (N5BF) has been
contemplating what it would take to do an amateur EarthVenusEarth
(after some of his experiments doing EME with 5 watts)..
Perhaps a better question is: What is the
Hi Bruce:
If a square meter of Styrofoam is 1.5 deg C/W then a cubic inch would be
39.37 * 39.37 * 1.5 or 2,325 deg C/W
The DS3231 dissipates about 1 mw when running. I'm not sure how to come
up with an allowable temp increase, but suspect it's based on not
exceeding the max allowed
Hal Murray wrote:
This, and similar impressive accomplishments, has prompted some
lunchtime discussion at work (JPL).. One of us (N5BF) has been
contemplating what it would take to do an amateur EarthVenusEarth
(after some of his experiments doing EME with 5 watts)..
Perhaps a better question
Hi
If a square meter of foam 2 thick is 1.5 C/W then a 1 square inch piece
(also 2 thick) would be ~40^2 times better.
Your cube has ~2 square inches on a side and six sides. (divide by ~12)
The outer cube after you put 2 of foam on it has surfaces 5.6 on a side.
That's a surface area of 25
On 3/10/10, David Forbes dfor...@dakotacom.net wrote:
With regard to the restoration and use of a derelict radio telescope for
amateur radio, that's a fine example of amateurs putting themselves to a big
task and succeeding. I work on radio telescopes, so I know how big a task
that is.
Surely you meant 1 square inch of styrofoam with the specified thickness??
For a 100 hour (3.6E5 seconds) time constant and 1000 deg C/W thermal
resistance you need a thermal capacitance of 3.6E5/1E3 = 360 J/C
or 360/0.8371 = 430 gm of Aluminium which has a volume of 430/2.7 = 159 cc.
You
This thread mentioned puilsars and the best clocks. Here are some comments
from those really in the know:
==
Latest Al+ clock comparision at NIST is at better than 10^-17 level see.
http://arxiv.org/abs/0911.4527
==
rich...@karlquist.com said:
I vaguely remember reading that
Looking at the specific heat of metals:
http://www.engineeringtoolbox.com/specific-heat-metals-d_152.html
Wouldn't Beryllium be better instead of aluminium?
I could foresee a few problems though eg machining holes at home,
never mind where to get a block from.
Phil
Hi
The gotcha is that you are interested in the amount of heat per cubic foot
rather than the amount of heat per pound. You need to take the standard heat
per weight numbers and convert them to heat per volume numbers.
Of the things you can easily get, copper is good. Steel is not as good as
A better metric may be stored heat for a dollar's worth of material. Scrap
iron is pretty cheap.
From:
Bob Camp li...@rtty.us
To:
Discussion of precise time and frequency measurement time-nuts@febo.com
Date:
03/10/2010 06:03 PM
Subject:
Re: [time-nuts] Thermal time constant
Sent by:
p...@pseng.org.uk wrote:
Looking at the specific heat of metals:
http://www.engineeringtoolbox.com/specific-heat-metals-d_152.html
Wouldn't Beryllium be better instead of aluminium?
I could foresee a few problems though eg machining holes at home,
never mind where to get a block from.
Phil
Just in case anyone finds a beryllium brick somewhere and tries to
use it:
Beryllium is very very poisonous.
cheers,
Neville Michie
On 11/03/2010, at 10:08 AM, Bruce Griffiths wrote:
p...@pseng.org.uk wrote:
Looking at the specific heat of metals:
There's at least one known case where someone attempted to grind a
beryllium mirror substrate using conventional methods without proper
control of dust resulting in his death.
Bruce
Neville Michie wrote:
Just in case anyone finds a beryllium brick somewhere and tries to use
it:
Beryllium is
Hi
The same caution applies to the beryllium in beryllium oxide heat spreaders.
You find them in old RF transistors and some RF tubes.
Bob
On Mar 10, 2010, at 6:45 PM, Bruce Griffiths wrote:
There's at least one known case where someone attempted to grind a beryllium
mirror substrate using
Beryllium copper parts are also an issue although the beryllium content
is only 0.3%-0.5% by weight.
Bruce
Bob Camp wrote:
Hi
The same caution applies to the beryllium in beryllium oxide heat spreaders.
You find them in old RF transistors and some RF tubes.
Bob
On Mar 10, 2010, at 6:45
Hi
So getting back to the original idea.
Taking the other extreme - if you go for ~20 C / W on the insulation:
The mass of the block will be ~50X what it was before.
1.6 on a side goes to ~5 on a side.
Surface area goes up ~10X.
200 C/W with 2 foam goes to 20 C/W
Outer surface area goes
The suggestion of beryllium was somewhat tongue-in-cheek ie not to be
taken seriously, I did mention there would be a few problems, death
being somewhat a terminal one.
I agree with Bruce that specific heat*density is what is really
required (I'd forgotten how light beryllium is. I don't
Hi Bob:
I like the idea of a six inch on a side cube. An outer aluminum box,
styrofoam insulation, and a block of (copper, Aluminum, etc.) in the
center. A DS3231 or similar RTC and a PIC with a DB-9 connector on one face.
Have Fun,
Brooke Clarke
http://www.PRC68.com
Bob Camp wrote:
Hi
I have been wondering about achieving the rated thermal resistance
from plastic foam,
the problem being that radiant transmission may be very strong
through the foam.
What happens if you interleave concentric sheets of foam plastic with
aluminium foil? (taking care to keep the foil
on
Hi
That raises the interesting question of weather radiant transfer is already
included in the rated thermal resistance. My guess is that the 8 of foam is
enough to cover any radiation issues and still get you above 20 C / W.
Since you are probably starting with 1 or 2 slabs, including the
Radiative heat transfer (for a surface with an emissivity of 1) is
around 150uW/square cm /degreeC at 300K.
That's equivalent to about 10cm of styrofoam.
It seems unlikely that the radiative heat transfer component is included
in the thermal resistance rating for Styrofoam.
The radiative
Oops forgot a factor of 4
Radiative heat transfer for surface with an emissivity of 1 at 300K is
about 612uW/square cm/degree C
which is equivalent to about 25mm of styrofoam.
Which raises the question what's the emissivity of the isothermal
surface used when measuring the thermal resistance
Hi
Since styrofoam is being rated as a building insulation, it's reasonable to
believe that the material on both sides is up around 1. I highly doubt that
somebody tossing styrofoam in walls is going to add a radiation factor ...
In our application we're talking about a metal block inside a
There's a small problem with my calculation and the published figures
for the thermal resistance of styrofoam.
If the measurements include radiative transfers the thermal resistance
per unit area of a styrofoam slab should reach a limiting value (when
the radiative transfer component dominates)
Hi
Low density (1 or 2 lb / cu ft) urethane foam is going to be a better insulator
than styrofoam. I believe it's reasonably opaque at IR.
Bob
On Mar 10, 2010, at 8:23 PM, Bruce Griffiths wrote:
There's a small problem with my calculation and the published figures for the
thermal
Depends on the duration of the experiment.
Urethanes arent well known for stability.
The low thermal resistance of close cell urethanes is largely due to
their better retention of the blowing agent which has lower thermal
conductivity than air.
Closed cell foam glass (however the sulphur
Hi all --
I have the info for setting up the output freq. Has anyone managed
to snag the info for the test points and adjustments in this beast?
thanx!
-ls-
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Hi
Like pretty much every other rubidium on the planet - no, not as far as I know.
Most of the test points and adjustments are of the even if we told you, you
aren't set up to use it nature. Put another way, they would have to provide a
lot of proprietary information to enable you to do
Has anyone compiled a taxonomy of the apparently numerous variants of
10811 OXOs? (Distinguishing features, rated performance, used in
what instruments, etc.)
Also, I found Mark's observation that 10544s may drift less than
10811s interesting. I own several 10544As and have experience with
Brooke Clarke wrote:
Hi Bruce:
What does m2K/W mean? See:
http://building.dow.com/europe/uk/proddata/styrofoam/thermal.htm
50 mm it's about 1.5 and for 100 mm it's about 3.
thermal resistance (you can tell because it's degrees/watt, as opposed
to watts/degree which would be conductivity)
Hal Murray wrote:
This, and similar impressive accomplishments, has prompted some
lunchtime discussion at work (JPL).. One of us (N5BF) has been
contemplating what it would take to do an amateur EarthVenusEarth
(after some of his experiments doing EME with 5 watts)..
Perhaps a better question
Brooke Clarke wrote:
Hi Bruce:
If a square meter of Styrofoam is 1.5 deg C/W then a cubic inch would be
39.37 * 39.37 * 1.5 or 2,325 deg C/W
The DS3231 dissipates about 1 mw when running. I'm not sure how to come
up with an allowable temp increase, but suspect it's based on not
exceeding
Charles P. Steinmetz wrote:
Has anyone compiled a taxonomy of the apparently numerous variants of
10811 OXOs? (Distinguishing features, rated performance, used in what
instruments, etc.)
Charles, if you have not already seen it there is a manual, I think on
the Time Lord, TvB's site that
If you like starting from scratch, get a copy of Procedures in
Experimental Physics by John Strong.
-John
===
Hal Murray wrote:
This, and similar impressive accomplishments, has prompted some
lunchtime discussion at work (JPL).. One of us (N5BF) has been
contemplating what it would
Bob Camp wrote:
Hi
The gotcha is that you are interested in the amount of heat per cubic foot rather than the amount of heat per pound. You need to take the standard heat per weight numbers and convert them to heat per volume numbers.
Of the things you can easily get, copper is good. Steel is
Bob Camp wrote:
Hi
Like pretty much every other rubidium on the planet - no, not as far as I know.
Most of the test points and adjustments are of the even if we told you, you aren't set up to use it nature. Put another way, they would have to provide a lot of proprietary information to enable
Gawd, tell me about it... I just got through rebuilding the drive roller in
half a dozen Tektronix YT-1 and YT-1S chart recorders for the
1502B/1520C/1503B/1503C TDR's. The recorders were built by AstroMed and the
roller was made of a black urethane that reverts back to its primordial
Bob Camp wrote:
My personal experience suggests that setting one up is indeed a black art known
only to the select few. The high priest takes them into the back room and they
magically come return in working order several days / weeks / what ever later.
High priest goes on vacation - not
J. Forster wrote:
If you like starting from scratch, get a copy of Procedures in
Experimental Physics by John Strong.
-John
And, relevant to the thermal time constant discussion.. That book has a
great section on thermal diffusion and conductivity, along with a chart
of material
jimlux wrote:
J. Forster wrote:
If you like starting from scratch, get a copy of Procedures in
Experimental Physics by John Strong.
-John
And, relevant to the thermal time constant discussion.. That book has a
great section on thermal diffusion and conductivity, along with a chart
of
water is pretty good, too and cheap. Coupling to it is easy as well.
Don
- Original Message -
From: jimlux jim...@earthlink.net
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Wednesday, March 10, 2010 9:35 PM
Subject: Re: [time-nuts] Thermal time
That's a common question; rest assured you are not alone in your confusion.
One of us -- Mark or myself or some other doughty volunteer -- *will*
eventually write a user guide of some sort... but the software itself is
still undergoing too many tweaks. It's a bit too soon to nail down the UI
by
)
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and follow the instructions there.
__ Information from ESET NOD32 Antivirus, version of virus
signature database 4933 (20100310
Hi Charles,
See http://www.leapsecond.com/museum/10811a/90027-1.pdf for details of the
10811D/E versions and options. It's been appended to this copy of the A/B
manual http://www.hparchive.com/Manuals/HP-10811AB-Manual.pdf
Hope this helps.
Robert G8RPI.
--- On Thu, 11/3/10, Charles P.
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