Message: 2
Date: Wed, 09 Sep 2009 14:53:15 -0600
From: Brent Gordon <[email protected]>
Subject: Re: [time-nuts] HP 5328 PSU nightmare... Or stupid engineer,
you decide...
To: [email protected], Discussion of precise time and
frequency measurement <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset=EUC-KR
I'm not familiar with this particular instrument, but a standard
technique for linear power supplies is to hook it up to a variac. This
lets you turn down the line voltage so you can do some measurements
without smoking the system.
Brent
Douglas Wire - PUPCo Studios wrote:
Good day everyone and thank you all for hosting this wonderful
community
and allowing me to participate. I have several HP5328 with the ?
really-
nice? newer 10811-xxxxx Oscillators in them. I have found while I
have
used the good old gold trace reliable HP instruments all of my
life, these
units have been especially difficult. The first unit the 4500uF
electrolytic?s went bad and produced essentially a dead short; an
easy
enough repair for me to not only track down in minutes, but it only
takes a
straight bit screwdriver to fix in seconds!
Now our second unit has been giving me fits and while I would agree
100%
with one of the posts I saw here about how well HP did not only
with their
schematics, but also the wonderful troubleshooting flow charts
usually make
repairs on any of their old units a breeze. Sadly I have a unit
here that
is giving us fits! It is a PSU issue and not related to the
Motherboard or
any of the cards as I tested it with everything unhooked/
unsoldered and
still got the same result. It is quite similar to what we see when
we get
an old HP unit that has a fried cap and is darn near creating a
short to
ground, but alas I simply cannot find the problem (I am sure it is
starring
me in the face is and I just can?t see it?) What I am seeing is super
high current flow through the R1 (I believe, but HP?s every unit I
have
ever serviced had.47? resistor, NOT a 22-? as is stated in the
schematic?) that leads to F1. The troubleshooting is complicated by
the
fact that unless I want to smoke that heavy duty, relatively close
tolerance resistor, I cannot even check voltages anywhere for it
will blow
the fuse or if I put a slow blow to try and catch some measurements
in a
second or two, well that is not very feasible either.
If I had to guess, I would say it has either a cap that has fried,
outside
chance of a transformer issue, or the way this thing reacts, pretty
well an
effective dead short somewhere, but I will be damned if I can find
the
problem anywhere. I replaced the bad and 4500uF caps as well as the
rectifier, wondering if part of it had blown with no change in its
issues.
One cannot follow the flow cart to much of anything other than
boxes that
say look for a short, but so many areas one tests even on a perfectly
working unit come clear down near the zero ? point even when they are
operating correctly.
I apologize if 1) this is not a clear email that anyone can easily
understand and 2) I almost feel embarrassed to ask anyone for
advice from
their practical experience, for I feel as If I should easily be
able to get
to the bottom of this in a matter of minutes with the wonderful
data HP
provides us all for these old workhorses.
So if anyone has run into a problem such as this in the past where
working
the flow chart only yields No, No, No -> check for shorts and has any
advice for how I might logically proceed, or what in fact you have
found
out in dealing with a similar problem, it would be of great help,
as we
need this in-service ASAP, but I guess I just cannot see the forest
for the
tress in front of me or something here? Any advise, suggestions
would be
greatly appreciated.
I would like to become a more active participant here with all I can
contribute, which hopefully soon should be a lot as I am doing some
innovative timing and generation processes that I am relatively
sure the
outcome and data from derived from it could be of great benefit to
the TIME-
NUTS userbase here. Thanks and don?t be too hard on me for asking
(what to
me sounds like a stupid amateur question) but I am either too tired
to
reason correctly, or it is just one of those very pesky problems,
that
hopefully someone has identified before and might be able to
enlighten us
over. I am begiinign to wonder if a voltage regulator might be
responsible,
but I am at a loss at the moment and have not had enough sleep to
properly
think this repair through? Thank you again everyone!
Warm regards,
Douglas M. Wire, GED, FNA,
PUPCo Studios, PUPCo Research Group
------------------------------
Message: 3
Date: Wed, 9 Sep 2009 14:00:50 -0700
From: Corby Dawson <[email protected]>
Subject: [time-nuts] 5071A tube EEPROM and tube data
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset=us-ascii
"The HP tubes used a heated metal "burst" diaphragm not glass ampoules
to"
Dave,
Actually, YES.
I dug up the oven I had opened up and it is as I remembered.
The cesium ampoule is all metal and sits upside down in the center
of the
"wicking" screen.
The center of the burst diaphragm is welded to a post that comes out
the
top of the oven via an insulated feedthru.
When they want to free the cesium they apply a high current thru the
post
and it melts a hole where the post was welded to the diaphragm.
NO glass inside the wicking or inside the ampoule.
I'm not saying other tubes dont have glass but HP tubes DO NOT.
I'll see if I can look thru my box of ovens and if I have an FTS oven
I'll cut it open and see.
Corby Dawson
I do have PIX of the above but nowhere to post them!
____________________________________________________________
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------------------------------
Message: 4
Date: Thu, 10 Sep 2009 09:10:24 +1200
From: Bruce Griffiths <[email protected]>
Subject: Re: [time-nuts] HP 5328 PSU nightmare... Or stupid engineer,
you decide...
To: Discussion of precise time and frequency measurement
<[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset=EUC-KR
Neither the linear regulators nor the switching regulators in the
5328A have
any explicit current limiting circuitry other than that provided by
the
pass transistor current gain and the limited current available from
the
pass element driver.
The only protection against long term load faults is provided by the
fuses
at the regulator inputs. However these fuses don't protect against
shorted rectifier output filter capacitors etc.
Bruce
Brent Gordon wrote:
I'm not familiar with this particular instrument, but a standard
technique for linear power supplies is to hook it up to a variac.
This
lets you turn down the line voltage so you can do some measurements
without smoking the system.
Brent
Douglas Wire - PUPCo Studios wrote:
Good day everyone and thank you all for hosting this wonderful
community
and allowing me to participate. I have several HP5328 with the ?
really-
nice? newer 10811-xxxxx Oscillators in them. I have found while I
have
used the good old gold trace reliable HP instruments all of my
life, these
units have been especially difficult. The first unit the 4500uF
electrolytic?s went bad and produced essentially a dead short; an
easy
enough repair for me to not only track down in minutes, but it
only takes a
straight bit screwdriver to fix in seconds!
Now our second unit has been giving me fits and while I would
agree 100%
with one of the posts I saw here about how well HP did not only
with their
schematics, but also the wonderful troubleshooting flow charts
usually make
repairs on any of their old units a breeze. Sadly I have a unit
here that
is giving us fits! It is a PSU issue and not related to the
Motherboard or
any of the cards as I tested it with everything unhooked/
unsoldered and
still got the same result. It is quite similar to what we see when
we get
an old HP unit that has a fried cap and is darn near creating a
short to
ground, but alas I simply cannot find the problem (I am sure it is
starring
me in the face is and I just can?t see it?) What I am seeing is
super
high current flow through the R1 (I believe, but HP?s every unit I
have
ever serviced had.47? resistor, NOT a 22-? as is stated in the
schematic?) that leads to F1. The troubleshooting is complicated
by the
fact that unless I want to smoke that heavy duty, relatively close
tolerance resistor, I cannot even check voltages anywhere for it
will blow
the fuse or if I put a slow blow to try and catch some
measurements in a
second or two, well that is not very feasible either.
If I had to guess, I would say it has either a cap that has fried,
outside
chance of a transformer issue, or the way this thing reacts,
pretty well an
effective dead short somewhere, but I will be damned if I can find
the
problem anywhere. I replaced the bad and 4500uF caps as well as the
rectifier, wondering if part of it had blown with no change in its
issues.
One cannot follow the flow cart to much of anything other than
boxes that
say look for a short, but so many areas one tests even on a
perfectly
working unit come clear down near the zero ? point even when they
are
operating correctly.
I apologize if 1) this is not a clear email that anyone can easily
understand and 2) I almost feel embarrassed to ask anyone for
advice from
their practical experience, for I feel as If I should easily be
able to get
to the bottom of this in a matter of minutes with the wonderful
data HP
provides us all for these old workhorses.
So if anyone has run into a problem such as this in the past where
working
the flow chart only yields No, No, No -> check for shorts and has
any
advice for how I might logically proceed, or what in fact you have
found
out in dealing with a similar problem, it would be of great help,
as we
need this in-service ASAP, but I guess I just cannot see the
forest for the
tress in front of me or something here? Any advise, suggestions
would be
greatly appreciated.
I would like to become a more active participant here with all I can
contribute, which hopefully soon should be a lot as I am doing some
innovative timing and generation processes that I am relatively
sure the
outcome and data from derived from it could be of great benefit to
the TIME-
NUTS userbase here. Thanks and don?t be too hard on me for asking
(what to
me sounds like a stupid amateur question) but I am either too
tired to
reason correctly, or it is just one of those very pesky problems,
that
hopefully someone has identified before and might be able to
enlighten us
over. I am begiinign to wonder if a voltage regulator might be
responsible,
but I am at a loss at the moment and have not had enough sleep to
properly
think this repair through? Thank you again everyone!
Warm regards,
Douglas M. Wire, GED, FNA,
PUPCo Studios, PUPCo Research Group
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time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
------------------------------
Message: 5
Date: Wed, 09 Sep 2009 22:24:43 +0100
From: Dave Ackrill <[email protected]>
Subject: Re: [time-nuts] High accuracy? GPS position
To: Discussion of precise time and frequency measurement
<[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Murray Greenman wrote:
Mark,
How do you KNOW your position to such accuracy? Is it in fact
possible
to survey your position to that accuracy by any independent means?
If, for example, you use official survey marks to determine your
position by direct measurement, are the survey marks really that
accurate?
Yes, I have a National Survey Bolt mark just down the road from me.
Dave (G0DJA)
------------------------------
Message: 6
Date: Wed, 9 Sep 2009 17:54:12 EDT
From: [email protected]
Subject: Re: [time-nuts] High accuracy? GPS position
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset="US-ASCII"
In a message dated 09/09/2009 22:25:22 GMT Daylight Time,
[email protected] writes:
How do you KNOW your position to such accuracy? Is it in fact
possible
to survey your position to that accuracy by any independent means?
If, for example, you use official survey marks to determine your
position by direct measurement, are the survey marks really that
accurate?
Yes, I have a National Survey Bolt mark just down the road from me.
--------------------
I'm not sure that completely answers the question.
Even if we assume that the position of the bolt mark is known to an
accuracy of an inch or so, have you measured your antenna position
in relation to
that with sufficient precision in distance and bearing so as to
transfer
that accuracy to the antenna location?
regards
Nigel
GM8PZR
------------------------------
Message: 7
Date: Wed, 9 Sep 2009 23:43:46 +0000
From: Mark Sims <[email protected]>
Subject: Re: [time-nuts] time-nuts Digest, Vol 62, Issue 25
To: <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
I have a geodetic grade Ashtech Z12 GPS receiver and antenna. You
collect data with it (both L1 and L2 carrier phase) and email the
data to the National Geodetic Survey OPUS processing system. They
crunch the numbers and come back with a location (it's free).
The location is calculated by crunching the numbers against the data
collected simultaneously at 3-9 CORS reference stations. The CORS
network is a network of several hundred fixed high-precision GPS
stations that continuously collect data and monitor and cross-check
each other.
Included in the OPUS results is an error estimate. I have done
several runs and the error estimates are usually under 4mm. However
if you compare the spread in the actual locations generated, they
are usually within 400 microns.
I am pretty darn sure I know where I am... except that I am
drifting across the planet at about 10 mm / year. (The location
info for the CORS reference stations includes a velocity vector).
And let's not get into things like thermal expansion of my front
deck and tidal deformation of the earth's crust...
----------------------------------------
How do you KNOW your position to such accuracy? Is it in fact
possible to survey your position to that accuracy by any independent
means?
_________________________________________________________________
Windows Live: Keep your friends up to date with what you do online.
http://windowslive.com/Campaign/SocialNetworking?ocid=PID23285::T:WLMTAGL:ON:WL:en-US:SI_SB_online:082009
------------------------------
Message: 8
Date: Wed, 9 Sep 2009 20:48:08 -0500
From: "Jeff Schmidt" <[email protected]>
Subject: [time-nuts] FreeBSD: ntpd PPS vs. kernel PPS
To: <[email protected]>
Message-ID: <001201ca31b8$bfc2f950$3f48eb...@org>
Content-Type: text/plain; charset="us-ascii"
So, I have been running a FreeBSD GPS disciplined NTP server for
some time.
While there is a lot of guidance out there about how to do-it-
yourself with
a Garmin LVC 18 and FreeBSD, I was unable to find any quantitative
data
about whether the PPS was best handled in the FreeBSD kernel or in
the ntpd
driver. So, here is some data:
FreeBSD tick.jschmidt.org 7.2-RELEASE
Kernel PPS discipline was enabled as follows:
Kernel built with "options PPS_SYNC" (GENERIC + PPS_SYNC)
Relevant portions of ntp.conf:
# GPS NMEA (numbers seconds only)
server 127.127.20.0 prefer minpoll 4 maxpoll 4
#flag3 Controls the kernel PPS discipline: 0 for disable
(default), 1 for
enable.
fudge 127.127.20.0 flag3 1
# GPS PPS
server 127.127.22.0 minpoll 4 maxpoll 4
#flag3 Controls the kernel PPS discipline: 0 for disable
(default), 1 for
enable.
fudge 127.127.22.0 flag3 1
fudge 127.127.22.0 refid GPS
Similarly, ntpd PPS discipline was enabled as follows:
No "options PPS_SYNC" (just a GENERIC kernel)
ntp.conf:
fudge 127.127.20.0 flag3 0
fudge 127.127.22.0 flag3 0
No other changes - software, environmental, etc. See the graphs here:
http://www.jschmidt.org/loops.jpg
http://www.jschmidt.org/loops2.jpg
The box was running the ntpd PPS discipline from approximately 14260
thru
14445. It was running kernel PPS discipline prior to 14260 and
after 14445.
Visually, you can clearly see that the kernel PPS discipline is
superior to
the ntpd PPS discipline.
# ntpdc -c version
ntpdc [email protected] Sat Jul 18 14:35:11 UTC 2009 (1)
# ntptime
ntp_gettime() returns code 0 (OK)
time ce52bc08.62922d70 Wed, Sep 9 2009 19:43:04.385, (.385043152),
maximum error 995 us, estimated error 1 us, TAI offset 34
ntp_adjtime() returns code 0 (OK)
modes 0x0 (),
offset 5.788 us, frequency -11.256 ppm, interval 256 s,
maximum error 995 us, estimated error 1 us,
status 0x2107 (PLL,PPSFREQ,PPSTIME,PPSSIGNAL,NANO),
time constant 4, precision 0.001 us, tolerance 496 ppm,
pps frequency -11.256 ppm, stability 0.027 ppm, jitter 0.933 us,
intervals 17651, jitter exceeded 13839, stability exceeded 0,
errors 5.
Hope this is interesting/helpful, thx,
Jeff Schmidt
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End of time-nuts Digest, Vol 62, Issue 27
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