Re: [time-nuts] HP-5245L Parts
At 04:18 PM 5/24/2006, Allan W. Bart, Jr. wrote:
These units are still plentiful, you might want to go to a local
hamfest or ebay, the better deals are at the hamfests.
Allan
The side frames are common to many instruments of the period. Some
power supply parts are common to the 5246, 5245 and 5248 (the 5246 is
a skun down 5245, the 5248 goes to 150MHz as I recall).
The 5245L suffers for frequency comparison because it has only a
period average (no Time Interval Average) and the period average is
only good to 300kHz. The 5262A doesn't support averaging either, so
it or the 5263A (same case I think) will only offer resolution of 100ns.
The 5345A will offer 2ns single shot time interval resolution and can
average over 1000 intervals giving 2ps resolution.
The ideal is the 5370A/B which has a single shot TI resolution of 20ps.
John
From: Bruce Lanning blanning@acadia.net
Date: Wed May 24 14:33:17 CDT 2006
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] HP-5245L Parts
Thanks Allan for the response. I have the HP-5245L and the HP-5262A Time
Interval Unit, but it is not working. Problems in the PS and the front
handle on the right side is broken off. I had planned to use this unit for
frequency comparison, but not sure this is what I want. Your comments would
be appreciated.
Bruce W1GBS
----- Original Message -----
From: "Allan W. Bart, Jr." allanba@verizon.net
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Wednesday, May 24, 2006 2:22 PM
Subject: Re: [time-nuts] HP-5245L Parts
Hello,
I have one of these units and it will never die, try fair radio in Lima
OH.
Allan Bart>
From: Bruce Lanning blanning@acadia.net
Date: Wed May 24 12:55:58 CDT 2006
To: time-nuts@febo.com
Subject: [time-nuts] HP-5245L Parts
Looking to buy a HP-5245 or equivalent for parts only. Need not be
working,
or complete.
If you have this animal and would be willing to part with it, please
contact
me directly at: blanning@acadia.net Thanks,
Bruce W1GBS in Maine
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What's a good entry-level time reference system? I'm doing this for
the fun/learning/hobby and can't dump $10k into it (without also
incurring the attendant lawyer's fee for the divorce settlement :-)
I think something along the lines of the TAPR TAC would be perfect if
they still made it. Are there other relatively low-cost GPS reference
systems out there?
Keith
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LtCol Keith E. Brandt, MD, MPH
USAF-NASA Aerospace Medicine Liaison Officer
Johnson Space Center, Houston, Texas
wd9get@amsat.org
Goodbye cruel world that was my home-
there's cleaner space out here to roam
Put my feet up on the moons of Mars-
sit back, relax, and count the stars
*This message transmitted with 100% recycled electrons
Hi Keith:
A lot depends on what you're trying to do.
Do you already have a counter that will make time interval measurements
and if so with a lot of averaging what's the smallest time interval you
can see? Do you already have frequency standard(s) and just want to use
GPS to check on them or discipline them? The features of the TAC may or
may not be a good fit to your needs. Can you elaborate on your goals /
interests / etc.?
Have Fun,
Brooke Clarke
--
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com
Keith E. Brandt, M.D. wrote:
What's a good entry-level time reference system? I'm doing this for
the fun/learning/hobby and can't dump $10k into it (without also
incurring the attendant lawyer's fee for the divorce settlement :-)
I think something along the lines of the TAPR TAC would be perfect if
they still made it. Are there other relatively low-cost GPS reference
systems out there?
Keith
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LtCol Keith E. Brandt, MD, MPH
USAF-NASA Aerospace Medicine Liaison Officer
Johnson Space Center, Houston, Texas
wd9get@amsat.org
Goodbye cruel world that was my home-
there's cleaner space out here to roam
Put my feet up on the moons of Mars-
sit back, relax, and count the stars
*This message transmitted with 100% recycled electrons
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Keith E. Brandt, M.D. said the following on 05/24/2006 06:06 PM:
What's a good entry-level time reference system? I'm doing this for
the fun/learning/hobby and can't dump $10k into it (without also
incurring the attendant lawyer's fee for the divorce settlement :-)
I think something along the lines of the TAPR TAC would be perfect if
they still made it. Are there other relatively low-cost GPS reference
systems out there?
Interesting question!
Assuming you mainly want to have a test-bed for learning and
experimentation, I'd say you want three things: 1) a local frequency
standard, 2) a frequency/time interval counter, and 3) a GPS or other
radio reference.
For the frequency standard, one of the surplus HP 10811A or 10544A oven
crystal oscillators ("OCXO") which can be had on eBay for $50 - $150
would be good, or one of the surplus Efratom Rubidium standards that go
for the $250 range -- each has its own advantages; the crystal will have
better short term stability and less phase noise, but the Rb will have
better long term stability and will need to be recalibrated far less often.
For the frequency counter/time interval counter, I am very partial to
the HP 5334A or B. They are quite cheap on eBay (usually less than $150
and have 2ns time interval resolution. As a bonus, many of them have
the high-stability option (001) that includes an HP 10811A oscillator,
and if you find one with the "channel C" option you will be able to read
frequency to 1.3GHz.
Finally for the GPS. We're in a state of flux right now because
Motorola sold their line of GPS receivers and the one everyone would
have recommended last year is no longer available. Nonetheless, you may
be able to find an M12+T receiver which is the best unit they had
available, or the slightly older UT+. You'll need an antenna, but you
don't necessarily need the TAC-2 -- all it really does is provide power
supply and I/O buffering. You can do that on a piece of perfboard if
you want.
There are lots of other neat toys, but with those three you'll have a
good frequency standard and a way to calibrate it.
Hope this helps.
73,
John
Hi Keith:
A lot depends on what you're trying to do.
Do you already have a counter that will make time interval
measurements
and if so with a lot of averaging what's the smallest time interval
you
can see? Do you already have frequency standard(s) and just want
to use
GPS to check on them or discipline them? The features of the TAC
may or
may not be a good fit to your needs. Can you elaborate on your
goals /
interests / etc.?
Have Fun,
Brooke Clarke
Thanks for the reply.
I am starting from essentially nothing. The most practical use I would
have is a primary source for NTP. Other than that, it would be
experimenting with setting up an accurate time source.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LtCol Keith E. Brandt, MD, MPH
USAF-NASA Aerospace Medicine Liaison Officer
Johnson Space Center, Houston, Texas
wd9get@amsat.org
Goodbye cruel world that was my home-
there's cleaner space out here to roam
Put my feet up on the moons of Mars-
sit back, relax, and count the stars
*This message transmitted with 100% recycled electrons
Keith E. Brandt, M.D. wrote:
Thanks for the reply.
I am starting from essentially nothing. The most practical use I would
have is a primary source for NTP. Other than that, it would be
experimenting with setting up an accurate time source.
You can forgo the local freq. std. if your just want to run an NTP
server. They're great to have, but can be added later. "Most" GPS's with
a serial connection will work well enough for many applications. The
Motorola OnCores are supposed to be quite good. I'd like to say I've got
mine up and running, but the truth is that I've spent the past week
dealing with the disaster of a fish pond in my back yard.
cheers,
glenn
At 06:31 PM 5/24/2006, John Ackermann N8UR wrote:
Keith E. Brandt, M.D. said the following on 05/24/2006 06:06 PM:
What's a good entry-level time reference system? I'm doing this for
the fun/learning/hobby and can't dump $10k into it (without also
incurring the attendant lawyer's fee for the divorce settlement :-)
I think something along the lines of the TAPR TAC would be perfect if
they still made it. Are there other relatively low-cost GPS reference
systems out there?
Interesting question!
Assuming you mainly want to have a test-bed for learning and
experimentation, I'd say you want three things: 1) a local frequency
standard, 2) a frequency/time interval counter, and 3) a GPS or other
radio reference.
For the frequency standard, one of the surplus HP 10811A or 10544A oven
crystal oscillators ("OCXO") which can be had on eBay for $50 - $150
would be good, or one of the surplus Efratom Rubidium standards that go
for the $250 range -- each has its own advantages; the crystal will have
better short term stability and less phase noise, but the Rb will have
better long term stability and will need to be recalibrated far less often.
You will often find that it is cheaper to buy a counter with the
high-stab oven option than to buy the oven separately.
For the frequency counter/time interval counter, I am very partial to
the HP 5334A or B. They are quite cheap on eBay (usually less than $150
and have 2ns time interval resolution. As a bonus, many of them have
the high-stability option (001) that includes an HP 10811A oscillator,
and if you find one with the "channel C" option you will be able to read
frequency to 1.3GHz.
The 5335A is also sold from about $100 up and has the oven option as
opt010, 1.3GHz is opt030 and opt040 - expanded HPIB control is worth
having if you plan to remote the counter at all.
A little heavier is the 5345A which can be equipped for operation all
the way to 40GHz or so at not a huge expense. It is one of my all
time favourites. It has 2ns resolution and counts direct to 500MHz.
They came as standard with the high stab oven, opt001 removes the
oven. Opt010 is very basic HPIB talk only, opt011 HPIB with remote
programming, opt012 is HPIB like 011 but has control of slope and
trigger level as well.
You can pay from $80 or so for basic counter with HPIB. Just get the
seller to confirm it is not Opt 001! The 5345 is heavy, and a bit
noisier than the newer 5334A/B or 5335A. To my m ind if you are
interested in frequerncy measurement, this counter can give you
flexibility well beyond anything else that mere mortals can afford
when coupled with various plug-ins and convertor heads.
73's, John (ex VK3ZJF)
Finally for the GPS. We're in a state of flux right now because
Motorola sold their line of GPS receivers and the one everyone would
have recommended last year is no longer available. Nonetheless, you may
be able to find an M12+T receiver which is the best unit they had
available, or the slightly older UT+. You'll need an antenna, but you
don't necessarily need the TAC-2 -- all it really does is provide power
supply and I/O buffering. You can do that on a piece of perfboard if
you want.
There are lots of other neat toys, but with those three you'll have a
good frequency standard and a way to calibrate it.
Hope this helps.
73,
John
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Well, since you are interested in NTP, what kind of computers do
you have? Can you run full NTP (not SNTP) on a Unix box?
If so, all that you need is an accurate 1 PPS signal. That can come
from various GPS devices, such as time antennas and portable devices
that have the output. The HP Z3801 is an old standby, used to sell
for about $300, another 30-100 for a plain antenna, but more modern
equipment may have dropped the price. There are also GPS to NTP
converters on eBay in that price range. Spectracom (not yet absorbed
by Symmetricom) comes to mind.
To do something interesting, like comparing performance, look at
1 PPS disciplined NTP vs. network NTP, picking servers from around
the world. Later you can graduate to what seems to turn this group
on - comparing down to 10E-14 with expensive instruments.
If your wife is giving you trouble (but you could afford it), try
what she does, withholding pleasure - cease physical contact until
she realizes that you are deadly serious about comparative time.
If you really can't afford anything but shipping costs, I may have
some things that you could use - as a beginner and not a dealer.
Can you repair circuit boards?
Regards,
Bill Hawkins
Hi John:
I'm using the HP 5345A opt 11 now and really like it. When in the Time
Interval mode (cesium s/n 1227 1 MHz on start and cesium s/n 1013 1 MHz
on stop) you can turn the Gate Time knob up from "MIN" to say "1 SEC".
What this does is to accumulate the gate times for as many receptive
measurements as it takes to get to a total of 1 second, so the number of
measurements depends on the actual TI being measured. For example with
1 SEC gate time and a TI of about 574 ns it takes about 3 seconds of
clock time per measurement. The display is like 574.419,441 nano
seconds. That's 574 nano seconds and 419 pico seconds and 441 femto
seconds. If you set the gate time longer you get more digits. So at 10
SEC you get 0.1 femto seconds resolution after a 30 second wait. Simply
fantastic!
It counts to 500 MHz without any plugins unlike the HP 5245 that needs a
plugin to get to 500 MHz. But a drawback to the early models is that
the air filter is buried behind the FRONT panel and needs servicing
something like twice a year. This required taking the counter apart.
In later versions they removed the air filter.
Although I can read HP-IB data in talk only mode, I haven't figured out
the secret of two way communication.
But the SR620 is still hands down my favorite TI counter. 16 digits with
a fixed weight on the positions is a really good layout.
Have Fun,
Brooke Clarke
John Day wrote:
At 06:31 PM 5/24/2006, John Ackermann N8UR wrote:
Keith E. Brandt, M.D. said the following on 05/24/2006 06:06 PM:
What's a good entry-level time reference system? I'm doing this for
the fun/learning/hobby and can't dump $10k into it (without also
incurring the attendant lawyer's fee for the divorce settlement :-)
I think something along the lines of the TAPR TAC would be perfect if
they still made it. Are there other relatively low-cost GPS reference
systems out there?
Interesting question!
Assuming you mainly want to have a test-bed for learning and
experimentation, I'd say you want three things: 1) a local frequency
standard, 2) a frequency/time interval counter, and 3) a GPS or other
radio reference.
For the frequency standard, one of the surplus HP 10811A or 10544A oven
crystal oscillators ("OCXO") which can be had on eBay for $50 - $150
would be good, or one of the surplus Efratom Rubidium standards that go
for the $250 range -- each has its own advantages; the crystal will have
better short term stability and less phase noise, but the Rb will have
better long term stability and will need to be recalibrated far less often.
You will often find that it is cheaper to buy a counter with the
high-stab oven option than to buy the oven separately.
For the frequency counter/time interval counter, I am very partial to
the HP 5334A or B. They are quite cheap on eBay (usually less than $150
and have 2ns time interval resolution. As a bonus, many of them have
the high-stability option (001) that includes an HP 10811A oscillator,
and if you find one with the "channel C" option you will be able to read
frequency to 1.3GHz.
The 5335A is also sold from about $100 up and has the oven option as
opt010, 1.3GHz is opt030 and opt040 - expanded HPIB control is worth
having if you plan to remote the counter at all.
A little heavier is the 5345A which can be equipped for operation all
the way to 40GHz or so at not a huge expense. It is one of my all
time favourites. It has 2ns resolution and counts direct to 500MHz.
They came as standard with the high stab oven, opt001 removes the
oven. Opt010 is very basic HPIB talk only, opt011 HPIB with remote
programming, opt012 is HPIB like 011 but has control of slope and
trigger level as well.
You can pay from $80 or so for basic counter with HPIB. Just get the
seller to confirm it is not Opt 001! The 5345 is heavy, and a bit
noisier than the newer 5334A/B or 5335A. To my m ind if you are
interested in frequerncy measurement, this counter can give you
flexibility well beyond anything else that mere mortals can afford
when coupled with various plug-ins and convertor heads.
73's, John (ex VK3ZJF)
Finally for the GPS. We're in a state of flux right now because
Motorola sold their line of GPS receivers and the one everyone would
have recommended last year is no longer available. Nonetheless, you may
be able to find an M12+T receiver which is the best unit they had
available, or the slightly older UT+. You'll need an antenna, but you
don't necessarily need the TAC-2 -- all it really does is provide power
supply and I/O buffering. You can do that on a piece of perfboard if
you want.
There are lots of other neat toys, but with those three you'll have a
good frequency standard and a way to calibrate it.
Hope this helps.
73,
John
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At 09:24 PM 5/24/2006, Brooke Clarke wrote:
Hi John:
I'm using the HP 5345A opt 11 now and really like it. When in the Time
Interval mode (cesium s/n 1227 1 MHz on start and cesium s/n 1013 1 MHz
on stop) you can turn the Gate Time knob up from "MIN" to say "1 SEC".
What this does is to accumulate the gate times for as many receptive
measurements as it takes to get to a total of 1 second, so the number of
measurements depends on the actual TI being measured. For example with
1 SEC gate time and a TI of about 574 ns it takes about 3 seconds of
clock time per measurement. The display is like 574.419,441 nano
seconds. That's 574 nano seconds and 419 pico seconds and 441 femto
seconds. If you set the gate time longer you get more digits. So at 10
SEC you get 0.1 femto seconds resolution after a 30 second wait. Simply
fantastic!
It counts to 500 MHz without any plugins unlike the HP 5245 that needs a
plugin to get to 500 MHz. But a drawback to the early models is that
the air filter is buried behind the FRONT panel and needs servicing
something like twice a year. This required taking the counter apart.
In later versions they removed the air filter.
Although I can read HP-IB data in talk only mode, I haven't figured out
the secret of two way communication.
Hmm, I am not sure if I have any code left lying around for the
thing. Possibly in RMB. I loved the 5345A, I lashed out as a young
man and bought my first one for some horrendous amount of money in
1972 when they first came out. I remember the HP salesman coming to
see me and he left me his demo unit. It was so pleased with it for
what I was doing that I insisted he leave it until he could get me
one for myself! Later I had occasion to purchase more of them and
when we pensioned them of in favour of newer devices, I picked one of
the newer ones with a 5355A plugin and a 5356B head for myself.
In a fit of inexplicable madness and incipient senility I let the
thing go last year for way too little money.
But the SR620 is still hands down my favorite TI counter. 16 digits with
a fixed weight on the positions is a really good layout.
I would love to get hold of an SR620, I have never used one but the
spec and manual certainly reads well. Now as a "tinkerer" I can't
afford to lash out the dollars I once could. I have a Tektronix
DC5010 - 3.25ns resolution as I recall. But to be honest I don't like
it. It does the job I need it for right now, but as soon as I find a
5370B or an SR620 I can afford, it will go.
Have Fun,
Brooke Clarke
Oh I am always having fun of some sort!
John Day