HP 5370B low frequency modulation
Hi fellow time-nuts,
As I was going to make a casual measurement of the HP 5370B 10 MHz output, i.e.
that of its HP 10811-60111 OCXO, I came to see an unexpected modulation. It has
a slow modulation frequency modulation of about 5,2 mHz or there abouts. Quite
digital/squarewave-like I might add. Not actually squarewave, but rather some
form of PWM signal. Another interesting aspect was that it had a fairly steady
high, abrupt fall down a slight recovery, a jump upwards and then fall up to
the steady high level. The high frequency was the longer part of the time.
The cycle-time of these are low, for the 200 5 sec samples I took, I had about
10 cycles or so. So it is about two minutes cycles. The rate varied greatly.
I have not seen any specific details in the HP 5370B service manual about where
the HP 10811-60111 EFC is hooked up to anything, but I have noticed that more
or less everything is grounded on the connector. Now, if there is low-frequency
modulations of any large current there, it may kreep in. But it seems a bit
high for that.
I used both a Pendelum CNT-90 as well as a HP 5372A to measure this. I used
both the Cs and Rb as reference and it made no difference. The CNT-90 between
the two showed only noise, so this quick and dirty three-cornered hat certainly
pointed its crookied finger at the HP 5370B. The HP 5372A was using its own
well heated 10811-60111 as reference but that told the same story.
I might add that the 5370B was running in "cabed" condition, i.e. top and
bottom lids where off as well as the right side. The top lid needs to be off if
you want to have a chance of trimming it. The 5370B has been in bypass 9 days,
so I consider the 10811 fairly heated.
Has anyone else seen this? Tom?
Cheers,
Magnus
Magnus Danielson wrote:
Hi fellow time-nuts,
As I was going to make a casual measurement of the HP 5370B 10 MHz output, i.e.
that of its HP 10811-60111 OCXO, I came to see an unexpected modulation. It has
a slow modulation frequency modulation of about 5,2 mHz or there abouts. Quite
digital/squarewave-like I might add. Not actually squarewave, but rather some
form of PWM signal. Another interesting aspect was that it had a fairly steady
high, abrupt fall down a slight recovery, a jump upwards and then fall up to
the steady high level. The high frequency was the longer part of the time.
The cycle-time of these are low, for the 200 5 sec samples I took, I had about
10 cycles or so. So it is about two minutes cycles. The rate varied greatly.
I have not seen any specific details in the HP 5370B service manual about where
the HP 10811-60111 EFC is hooked up to anything, but I have noticed that more
or less everything is grounded on the connector. Now, if there is low-frequency
modulations of any large current there, it may kreep in. But it seems a bit
high for that.
I used both a Pendelum CNT-90 as well as a HP 5372A to measure this. I used
both the Cs and Rb as reference and it made no difference. The CNT-90 between
the two showed only noise, so this quick and dirty three-cornered hat certainly
pointed its crookied finger at the HP 5370B. The HP 5372A was using its own
well heated 10811-60111 as reference but that told the same story.
I might add that the 5370B was running in "cabed" condition, i.e. top and
bottom lids where off as well as the right side. The top lid needs to be off if
you want to have a chance of trimming it. The 5370B has been in bypass 9 days,
so I consider the 10811 fairly heated.
Has anyone else seen this? Tom?
Cheers,
Magnus
Hej Magnus
Oscillation/cycling of oven temperature?
Oven controller oscillation?
Bruce
From: Dr Bruce Griffiths bruce.griffiths@xtra.co.nz
Subject: Re: [time-nuts] HP 5370B low frequency modulation
Date: Mon, 23 Jul 2007 11:14:25 +1200
Message-ID: 46A3E4D1.2000900@xtra.co.nz
Hej Magnus
Hej Bruce,
Oscillation/cycling of oven temperature?
Oven controller oscillation?
Might be, but then my "loadingcondition" has caused the oven control out of
stability. This would certainly supprice me. The oven control in the 10811 is
linear and for most practical purposes behave like a first-degree linear
diffrential system. OK, there might be a second degree aspect, but the poles
should be fairly stable and it would be more a pure "amplitude" problem.
Now as I was down putting the hood on (and removing some of the residues from
the not so very smart packaging, using isopropanol) the down-spikes had started
to become fewer and rare, and it had 490 uHz of Allan Deviation, i.e. 4,9E-11
for tau = 5 s. I beleive it will considerably lower as the spiking stops.
The full 10811 seems powered during standby mode. Some solutions will only have
the oven powered in standby. What does change on powerup of the rest of the
counter is that you turn on alot more heat, current, the fan (which has a fat
metall wall between the flow and the 10811, but that piece of metal wrapps the
10811 so the cool-of-effect may be there never the less.
After putting the lid on and letting it sit there the spikes is still evident
and last reading gives 5,8E-11 @ tau = 5s.
A comperative measure with another 10811 (which I just happend to have a
cable for lying around on the table) but which was unheated also gave time for
a little experiment, looking at the heat-up performance. Now, it started some
200 Hz hot, but went for a steady linear dive downwards which at about 400 s
curved upwards and had a gentle overshot (i.e. lower frequency) until it
stablized. However, subsequent measure showed a slow but steady rise and ADEV
measures was surely limited by the driftrate. It was however much lower, such
as 1.2E-11, and that includes the drift-rate tainting while the display
indicated a much smoother curve.
As I don't have a wiring aisle for my lab-bench (beleive me, I start to
consider it as a must have even if it would be a squeeze-in variant of 3-4
dm or so, I could not get the heated 10811 in my 5372A. I really need to hook
the backside panels up to a BNC patch any decade now. Anyway, otherwise I would
have a well heated alternative to measure on.
I wish I get a phonecall with good news from a fellow time-nut tomorrow. If so
I drive down to him. :-)
Cheers,
Magnus
Magnus Danielson wrote:
Hej Bruce,
Oscillation/cycling of oven temperature?
Oven controller oscillation?
Might be, but then my "loadingcondition" has caused the oven control out of
stability. This would certainly supprice me. The oven control in the 10811 is
linear and for most practical purposes behave like a first-degree linear
diffrential system. OK, there might be a second degree aspect, but the poles
should be fairly stable and it would be more a pure "amplitude" problem.
Now as I was down putting the hood on (and removing some of the residues from
the not so very smart packaging, using isopropanol) the down-spikes had started
to become fewer and rare, and it had 490 uHz of Allan Deviation, i.e. 4,9E-11
for tau = 5 s. I beleive it will considerably lower as the spiking stops.
The full 10811 seems powered during standby mode. Some solutions will only have
the oven powered in standby. What does change on powerup of the rest of the
counter is that you turn on alot more heat, current, the fan (which has a fat
metall wall between the flow and the 10811, but that piece of metal wrapps the
10811 so the cool-of-effect may be there never the less.
After putting the lid on and letting it sit there the spikes is still evident
and last reading gives 5,8E-11 @ tau = 5s.
A comperative measure with another 10811 (which I just happend to have a
cable for lying around on the table) but which was unheated also gave time for
a little experiment, looking at the heat-up performance. Now, it started some
200 Hz hot, but went for a steady linear dive downwards which at about 400 s
curved upwards and had a gentle overshot (i.e. lower frequency) until it
stablized. However, subsequent measure showed a slow but steady rise and ADEV
measures was surely limited by the driftrate. It was however much lower, such
as 1.2E-11, and that includes the drift-rate tainting while the display
indicated a much smoother curve.
As I don't have a wiring aisle for my lab-bench (beleive me, I start to
consider it as a must have even if it would be a squeeze-in variant of 3-4
dm or so, I could not get the heated 10811 in my 5372A. I really need to hook
the backside panels up to a BNC patch any decade now. Anyway, otherwise I would
have a well heated alternative to measure on.
I wish I get a phonecall with good news from a fellow time-nut tomorrow. If so
I drive down to him. :-)
Cheers,
Magnus
Hej Magnus
What I had in mind was perhaps a bad joint or component failure in the
oven regulator due to thermal cycling and or age of the oscillator.
Perhaps the oven regulator compensation capacitor??
Bruce
Hej Magnus
Could there perhaps be an intermittent thermal fuse in the 10811?
Bruce
Hej Magnus
Since the 10811 oven heater supply in a 5370 is unregulated one possible
cause is a quasi periodic variation of the mains supply voltage.
Bruce
I believe it is almost impossible to have an intermittent thermal fuse due
to their very clever design. Although over age they can open up. Once open,
however I do not believe they can connect again. The fuse is simply to
metallic contacts that are force to be in contact during assembly. Their
normal desired resting state would be to be not connected. When closed, the
fuse cavity is filled with wax, which mostly determines when the fuse opens
(temperature). With too much current through the fuse, the wax heats
allowing the contact to spring apart to their normal resting position. Now,
with no more current flowing, the wax hardens almost immediately, never
allowing the two contacts to meet again. - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Dr Bruce Griffiths
Sent: Sunday, July 22, 2007 9:39 PM
To: Magnus Danielson; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] HP 5370B low frequency modulation
); SAEximRunCond expanded to false
Errors-To: time-nuts-bounces+mfeher=eozinc.com+mfeher=eozinc.com@febo.com
Hej Magnus
Could there perhaps be an intermittent thermal fuse in the 10811?
Bruce
Mike Feher wrote:
); SAEximRunCond expanded to false
Errors-To: time-nuts-bounces+bruce.griffiths=xtra.co.nz+bruce.griffiths=xtra.co.nz@febo.com
I believe it is almost impossible to have an intermittent thermal fuse due
to their very clever design. Although over age they can open up. Once open,
however I do not believe they can connect again. The fuse is simply to
metallic contacts that are force to be in contact during assembly. Their
normal desired resting state would be to be not connected. When closed, the
fuse cavity is filled with wax, which mostly determines when the fuse opens
(temperature). With too much current through the fuse, the wax heats
allowing the contact to spring apart to their normal resting position. Now,
with no more current flowing, the wax hardens almost immediately, never
allowing the two contacts to meet again. - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
Mike
Whilst the fuse itself may not be the problem, it is a plugin component
and the contacts may be problematic.
Bruce
Highly unlikely, but, possible, especially if it was in a corrosive
atmosphere. Of course then I would expect to see evidence of corrosion on
other components. When we do not know the answer we can come up with so many
possibilities and not have one of them correct. I have run across a lot of
those defective fuses over the years as HP has been using them forever.
There was no real evidence as to why they opened, and that is why before I
guessed at just plain ageing and the wax eventually getting soft. I just
checked the current flow within the oscillator where the fuse used to be
plugged in, which was at least nice of them, and always found it to be
normal. I just took a piece of buss wire and plugged it into the same two
pins were the fuse used to be and never had a problem again. The situation
Magnus describes of course is very unusual, and, in reality would only be
found by a time nut as it is so miniscule. There is also some periodicity to
it, which does suggest some control loop problem, but, I would hate to even
take a guess. - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Dr Bruce Griffiths
Sent: Sunday, July 22, 2007 10:32 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] HP 5370B low frequency modulation
Mike Feher wrote:
); SAEximRunCond expanded to false
Errors-To:
time-nuts-bounces+bruce.griffiths=xtra.co.nz+bruce.griffiths=xtra.co.nz@febo
.com
I believe it is almost impossible to have an intermittent thermal fuse due
to their very clever design. Although over age they can open up. Once
open,
however I do not believe they can connect again. The fuse is simply to
metallic contacts that are force to be in contact during assembly. Their
normal desired resting state would be to be not connected. When closed,
the
fuse cavity is filled with wax, which mostly determines when the fuse
opens
(temperature). With too much current through the fuse, the wax heats
allowing the contact to spring apart to their normal resting position.
Now,
with no more current flowing, the wax hardens almost immediately, never
allowing the two contacts to meet again. - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
Mike
Whilst the fuse itself may not be the problem, it is a plugin component
and the contacts may be problematic.
Bruce
From: "Mike Feher" mfeher@eozinc.com
Subject: Re: [time-nuts] HP 5370B low frequency modulation
Date: Sun, 22 Jul 2007 22:58:00 -0400
Message-ID: 00b101c7ccd5$490ae6a0$0201a8c0@gsmacdq14es
Mike,
Highly unlikely, but, possible, especially if it was in a corrosive
atmosphere. Of course then I would expect to see evidence of corrosion on
other components. When we do not know the answer we can come up with so many
possibilities and not have one of them correct. I have run across a lot of
those defective fuses over the years as HP has been using them forever.
There was no real evidence as to why they opened, and that is why before I
guessed at just plain ageing and the wax eventually getting soft. I just
checked the current flow within the oscillator where the fuse used to be
plugged in, which was at least nice of them, and always found it to be
normal. I just took a piece of buss wire and plugged it into the same two
pins were the fuse used to be and never had a problem again. The situation
Magnus describes of course is very unusual, and, in reality would only be
found by a time nut as it is so miniscule. There is also some periodicity to
it, which does suggest some control loop problem, but, I would hate to even
take a guess. - Mike
May I also point out that there may be as low as short low period per 1000 s or
about 3-8 (rought estimate).
I am considering all kinds of possible reasons for it. The group certainly has
more experience shared among them than I have on these, so I concentrate on
observations.
I wonder if it may be some form of initial shock burnout that I am witnessing.
I have no idea how they are suppposed to look. It is not like you want to toss
your 10811s to the floor just to see how they behave as a result, now is there?
If I where making them I would, but with a thad more of science attached to it.
Cheers,
Magnus
Hej Magnus,
Did you consider switching the 5370 and the 5372 oscillators? Putting the
blame either with the osc or the hosting 5370.
--
Björn
On Mon, July 23, 2007 5:10, Magnus Danielson said:
); SAEximRunCond expanded to false
Errors-To: time-nuts-bounces+bg=lysator.liu.se+bg=lysator.liu.se@febo.com
From: "Mike Feher" mfeher@eozinc.com
Subject: Re: [time-nuts] HP 5370B low frequency modulation
Date: Sun, 22 Jul 2007 22:58:00 -0400
Message-ID: 00b101c7ccd5$490ae6a0$0201a8c0@gsmacdq14es
Mike,
Highly unlikely, but, possible, especially if it was in a corrosive
atmosphere. Of course then I would expect to see evidence of corrosion
on
other components. When we do not know the answer we can come up with so
many
possibilities and not have one of them correct. I have run across a lot
of
those defective fuses over the years as HP has been using them forever.
There was no real evidence as to why they opened, and that is why before
I
guessed at just plain ageing and the wax eventually getting soft. I just
checked the current flow within the oscillator where the fuse used to be
plugged in, which was at least nice of them, and always found it to be
normal. I just took a piece of buss wire and plugged it into the same
two
pins were the fuse used to be and never had a problem again. The
situation
Magnus describes of course is very unusual, and, in reality would only
be
found by a time nut as it is so miniscule. There is also some
periodicity to
it, which does suggest some control loop problem, but, I would hate to
even
take a guess. - Mike
May I also point out that there may be as low as short low period per 1000
s or
about 3-8 (rought estimate).
I am considering all kinds of possible reasons for it. The group certainly
has
more experience shared among them than I have on these, so I concentrate
on
observations.
I wonder if it may be some form of initial shock burnout that I am
witnessing.
I have no idea how they are suppposed to look. It is not like you want to
toss
your 10811s to the floor just to see how they behave as a result, now is
there?
If I where making them I would, but with a thad more of science attached
to it.
Cheers,
Magnus
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
From: Björn_Gabrielsson bg@lysator.liu.se
Subject: Re: [time-nuts] HP 5370B low frequency modulation
Date: Mon, 23 Jul 2007 09:34:35 +0200 (CEST)
Message-ID: 62656.87.227.52.225.1185176075.squirrel@webmail.lysator.liu.se
); SAEximRunCond expanded to false
Errors-To: time-nuts-bounces+magnus=rubidium.dyndns.org+magnus=rubidium.dyndns.org@febo.com
Hej Magnus,
Hej Björn,
Did you consider switching the 5370 and the 5372 oscillators? Putting the
blame either with the osc or the hosting 5370.
No, good thinking. That would be possible but there is a bit of a logistical
problem prohibiting that as a quick-test. The 5372 sits under a Tek 547 scope
which weighs alot.
Cheers,
Magnus
I have seen cold solder joints on thermal fuses and certain types of
capacitors, while the rest of the instrument was fine with no sign of
corrosion.
I think it has to do with the metal used for certain component leads. Either
they were never soldered well, or interface corrosion developed over time.
Gold plated connectors are a well known example.
Didier KO4BB
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Mike Feher
Sent: Sunday, July 22, 2007 9:58 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] HP 5370B low frequency modulation
Highly unlikely, but, possible, especially if it was in a corrosive
atmosphere. Of course then I would expect to see evidence of corrosion on
other components.
...
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
Hi Didier:
Would you elaborate on the comment "Gold plated connectors are a well known
example." Do you mean when soldered with Lead Tin solder instead of a silver
bearing solder or something else?
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
Didier Juges wrote:
); SAEximRunCond expanded to false
Errors-To: time-nuts-bounces+brooke=pacific.net+brooke=pacific.net@febo.com
I have seen cold solder joints on thermal fuses and certain types of
capacitors, while the rest of the instrument was fine with no sign of
corrosion.
I think it has to do with the metal used for certain component leads. Either
they were never soldered well, or interface corrosion developed over time.
Gold plated connectors are a well known example.
Didier KO4BB
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Mike Feher
Sent: Sunday, July 22, 2007 9:58 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] HP 5370B low frequency modulation
Highly unlikely, but, possible, especially if it was in a corrosive
atmosphere. Of course then I would expect to see evidence of corrosion on
other components.
...
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Magnus,
Have you used your 5372A reference output to drive the 5370B ref in?
Certainly easier than switching 10811As.
Pete Rawson
Brooke Clarke wrote:
); SAEximRunCond expanded to false
Errors-To: time-nuts-bounces+bruce.griffiths=xtra.co.nz+bruce.griffiths=xtra.co.nz@febo.com
Hi Didier:
Would you elaborate on the comment "Gold plated connectors are a well known
example." Do you mean when soldered with Lead Tin solder instead of a silver
bearing solder or something else?
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
Didier Juges wrote:
); SAEximRunCond expanded to false
Errors-To: time-nuts-bounces+brooke=pacific.net+brooke=pacific.net@febo.com
I have seen cold solder joints on thermal fuses and certain types of
capacitors, while the rest of the instrument was fine with no sign of
corrosion.
I think it has to do with the metal used for certain component leads. Either
they were never soldered well, or interface corrosion developed over time.
Gold plated connectors are a well known example.
Didier KO4BB
Brooke
Gold dissolves in the solder and a gold -tin intermetallic compound is
formed which severely reduces the joint integrity and ductility.
This can be circumvented by keeping the gold concentration in the solder
below 4%. Tin plating over the gold before soldering is sometimes used
to ensure this.
Bruce
Maybe some of you haven't seen this oscilloscope clock display yet:
http://www.makezine.com/blog/archive/2007/07/avr_oscilloscope_clock.html
--
Margaret Stephanie Leber CCP, SCJP, SCWCD
http://voicenet.com/~maggie
AOPA 925383 - Amateur Radio Station K3XS - ARRL 39280 - AMSAT 32844
"The art of progress is to preserve order amid change
and to preserve change amid order."-A.N.Whitehead
From: "Pete" peterawson@earthlink.net
Subject: Re: [time-nuts] HP 5370B low frequency modulation
Date: Mon, 23 Jul 2007 08:14:32 -0600
Message-ID: 002601c7cd33$ce56f520$0200a8c0@BASE1
); SAEximRunCond expanded to false
Errors-To: time-nuts-bounces+magnus=rubidium.dyndns.org+magnus=rubidium.dyndns.org@febo.com
Magnus,
Pete,
Have you used your 5372A reference output to drive the 5370B ref in?
Certainly easier than switching 10811As.
Lack of wiring isle (wrong spelling last time, sorry) prohibited that. It was
just too hard to get to at that moment. As I have another 10811 inside another
instrument I used that as a reference instead. Thanks to fellow time-nut Björn
who I just came home from I have an easier swap-option exercise to do as he was
kind enought to borrow me another 10811 which was easier to get to. Not in
metrical distance thought, but who cares, I was going there anyways. :-)
Anyway, I have no reason to think that the output buffer board would subtract
frequency for length periods of time, up to a minute. It would mean that what
is more or less amplifiers and logical gates would drop cycles with only one
dynamic and one static signal. It is much more reasnoble to assume that the
10811 itself experience some modulation.
Cheers,
Magnus
Brooke,
Thanks Bruce for the quick response, as always.
In my business, we typically dissolve the gold by dipping the solder cup in
a hot tin pot, which is replaced regularly, before soldering the wires. This
has been blessed by the major defense contractors for military applications.
Failure to do this typically results in weakening solder joints over time,
and delayed failures, particularly when there is mechanical and/or thermal
stress applied to the joint.
Didier KO4BB
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Dr Bruce Griffiths
Sent: Monday, July 23, 2007 9:29 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] HP 5370B low frequency modulation
Brooke Clarke wrote:
); SAEximRunCond expanded to false
Errors-To:
time-nuts-bounces+bruce.griffiths=xtra.co.nz+bruce.griffiths=xtra.co.nz@febo
.com
Hi Didier:
Would you elaborate on the comment "Gold plated connectors are a well
known
example." Do you mean when soldered with Lead Tin solder instead of a
silver
bearing solder or something else?
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
Didier Juges wrote:
); SAEximRunCond expanded to false
Errors-To:
time-nuts-bounces+brooke=pacific.net+brooke=pacific.net@febo.com
I have seen cold solder joints on thermal fuses and certain types of
capacitors, while the rest of the instrument was fine with no sign of
corrosion.
I think it has to do with the metal used for certain component leads.
Either
they were never soldered well, or interface corrosion developed over
time.
Gold plated connectors are a well known example.
Didier KO4BB
Brooke
Gold dissolves in the solder and a gold -tin intermetallic compound is
formed which severely reduces the joint integrity and ductility.
This can be circumvented by keeping the gold concentration in the solder
below 4%. Tin plating over the gold before soldering is sometimes used
to ensure this.
Bruce
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
From: "Didier Juges" didier@cox.net
Subject: Re: [time-nuts] HP 5370B low frequency modulation
Date: Mon, 23 Jul 2007 21:12:39 -0500
Message-ID: 000001c7cd98$1c8d3dd0$6601a8c0@didierhp
Brooke,
Thanks Bruce for the quick response, as always.
In my business, we typically dissolve the gold by dipping the solder cup in
a hot tin pot, which is replaced regularly, before soldering the wires. This
has been blessed by the major defense contractors for military applications.
Failure to do this typically results in weakening solder joints over time,
and delayed failures, particularly when there is mechanical and/or thermal
stress applied to the joint.
Gold will dissolve very quickly into the Sn/Pb solder.
If you have a too high gold content in the joint, it can form one of several
Au/Sn mixtures which is brittle and will crack easilly. We had trouble with
that under our BGAs so when the gold layer was too thick, the whole 400-500
ball BGA could crack loose of the board if you accidentilly hit the rather
flimsy cooling flange. On another board we glued a nut to the top of the BGA
and hanged 50-70 kg of it and while the board was clearly bent the BGA was
still firmly hooked to it. Now that's the difference between a few um of gold
too much or not.
There are other cases where the gold-plating is not an issue.
This has been covered in public sources, so a dig around would give some
indication.
Cheers,
Magnus
Magnus and the group,
in hi-rel projects and in our space and satellite projects we have
procedures to remove at least most of the gold cover eg. by
presoldering the contact areas and then sucking both, tin and gold,
away. Properly done the clean areas can then undergo the final soldering
process. So far all our satellites do work very well and years longer
than planned. I do not remember having had in 25 years ever real problems
with good prepared solder joints. Of course, the best is avoiding gold
contacts for solder joints at all and never use nickel plated surfaces for
solder joints!
The NASA does have similar special procedures as the ESA.
The best is using adequate crimping processes where possible.
regards,
Arnold
On Tue, 24 Jul 2007 04:36:40 +0200 (CEST), Magnus Danielson wrote:
From: "Didier Juges" didier@cox.net
Subject: Re: [time-nuts] HP 5370B low frequency modulation
Date: Mon, 23 Jul 2007 21:12:39 -0500
Message-ID: 000001c7cd98$1c8d3dd0$6601a8c0@didierhp
Brooke,
Thanks Bruce for the quick response, as always.
In my business, we typically dissolve the gold by dipping the solder cup in
a hot tin pot, which is replaced regularly, before soldering the wires. This
has been blessed by the major defense contractors for military applications.
Failure to do this typically results in weakening solder joints over time,
and delayed failures, particularly when there is mechanical and/or thermal
stress applied to the joint.
Gold will dissolve very quickly into the Sn/Pb solder.
If you have a too high gold content in the joint, it can form one of several
Au/Sn mixtures which is brittle and will crack easilly. We had trouble with
that under our BGAs so when the gold layer was too thick, the whole 400-500
ball BGA could crack loose of the board if you accidentilly hit the rather
flimsy cooling flange. On another board we glued a nut to the top of the BGA
and hanged 50-70 kg of it and while the board was clearly bent the BGA was
still firmly hooked to it. Now that's the difference between a few um of gold
too much or not.
There are other cases where the gold-plating is not an issue.
This has been covered in public sources, so a dig around would give some
indication.
Cheers,
Magnus
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Hi Magnus,
The 5372A which we bought new years ago reference polluted by the
switching power supplies. There were more of them with different
frequencies. It showed up in the fft of measurements and also seen at
the reference output. I do not have access to that instrument anymore
and do not know the serial number. How is this with your 5372A?
Henk
On Jul 23, 2007, at 2:36, Magnus Danielson wrote:
As I don't have a wiring aisle for my lab-bench (beleive me, I
start to
consider it as a must have even if it would be a squeeze-in variant
of 3-4
dm or so, I could not get the heated 10811 in my 5372A. I really
need to hook
the backside panels up to a BNC patch any decade now. Anyway,
otherwise I would
have a well heated alternative to measure on.
I wish I get a phonecall with good news from a fellow time-nut
tomorrow. If so
I drive down to him. :-)
Cheers,
Magnus
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time-nuts
and follow the instructions there.
Gold mixes with solder to from an "intermetallic" that
suffers from "embrittlement". I am not aware of silver
solder being a remedy. I have heard of assembly lines
that do not allow any gold whatsoever in the building!
I heard our assembly line manager at work just
last week lecturing yet another engineer about NO GOLD.
Period!
Furthermore, gold plated brass connectors screwed into
aluminum (with corrosion treatment) (no soldering) will
corrode in a salt spray environment. I guarantee it.
We always used stainless for military work.
Rick N6RK
Brooke Clarke wrote:
Hi Didier:
Would you elaborate on the comment "Gold plated connectors are a well
known example." Do you mean when soldered with Lead Tin solder instead
of a silver bearing solder or something else?
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
Didier Juges wrote:
); SAEximRunCond expanded to false
Errors-To:
time-nuts-bounces+brooke=pacific.net+brooke=pacific.net@febo.com
I have seen cold solder joints on thermal fuses and certain types of
capacitors, while the rest of the instrument was fine with no sign of
corrosion.
I think it has to do with the metal used for certain component leads.
Either
they were never soldered well, or interface corrosion developed over
time.
Gold plated connectors are a well known example.
Didier KO4BB
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Mike Feher
Sent: Sunday, July 22, 2007 9:58 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] HP 5370B low frequency modulation
Highly unlikely, but, possible, especially if it was in a corrosive
atmosphere. Of course then I would expect to see evidence of corrosion on
other components. ...
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
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See:
and
http://www.tkb-4u.com/articles/soldering/sgons/sgons.php
There is also at least one US patent deals with using pure tin
instead of gold for solderability. The problems are also well known
to anyone working with flip-chip bonding where gold bumps have been
used. Both tin and gold have been known to grow crystalline whiskers,
one microscopy journal carried a paper a couple of years ago from
Sandia Lab on the subject. Tin whiskering has been well known for many years.
John
At 11:21 AM 8/30/2007, Richard (Rick) Karlquist wrote:
); SAEximRunCond expanded to false
Errors-To: time-nuts-bounces+johnday=wordsnimages.com@febo.com RETRY
Gold mixes with solder to from an "intermetallic" that
suffers from "embrittlement". I am not aware of silver
solder being a remedy. I have heard of assembly lines
that do not allow any gold whatsoever in the building!
I heard our assembly line manager at work just
last week lecturing yet another engineer about NO GOLD.
Period!
Furthermore, gold plated brass connectors screwed into
aluminum (with corrosion treatment) (no soldering) will
corrode in a salt spray environment. I guarantee it.
We always used stainless for military work.
Rick N6RK
Brooke Clarke wrote:
Hi Didier:
Would you elaborate on the comment "Gold plated connectors are a well
known example." Do you mean when soldered with Lead Tin solder instead
of a silver bearing solder or something else?
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
Didier Juges wrote:
); SAEximRunCond expanded to false
Errors-To:
time-nuts-bounces+brooke=pacific.net+brooke=pacific.net@febo.com
I have seen cold solder joints on thermal fuses and certain types of
capacitors, while the rest of the instrument was fine with no sign of
corrosion.
I think it has to do with the metal used for certain component leads.
Either
they were never soldered well, or interface corrosion developed over
time.
Gold plated connectors are a well known example.
Didier KO4BB
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Mike Feher
Sent: Sunday, July 22, 2007 9:58 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] HP 5370B low frequency modulation
Highly unlikely, but, possible, especially if it was in a corrosive
atmosphere. Of course then I would expect to see evidence of corrosion on
other components. ...
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
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and follow the instructions there.
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-----Original Message-----
From: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] On Behalf Of Richard
(Rick) Karlquist
Sent: Thursday, August 30, 2007 10:22 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] HP 5370B low frequency modulation
I have heard of assembly lines that do not allow any gold
whatsoever in the building!
That sounds totally unjustified. It's not like gold is going
to jump at the solder joint and contaminate it cold.
The effect of gold contamination is to weaken the joint (the
intermetallic compound of gold and tin is hard and brittle).
Over time, and particularly in high stress environments
(temperature cycling, vibrations), the solder joint
eventually breaks down at the interface and leaves you
with an intermittent connection.
The way we deal with it in the military business (where
temperature cycling and vibration is a way of life) is that
we first remove the gold plating from the solder pin side of
connector pins by tinning the pin a couple of times and each
time sucking the solder with fresh braid or other tool.
That dissolves the gold in solder that is then discarded,
leaving the solder end of the pin free of gold. At that point,
the pin can be soldered normally and the solder joint will show
good characteristics.
Alternately, we use a solder pot and dip the end of the part
that is to be cleaned in it. The problem with that is that
the concentration of gold in the pot increases over time until
the content of the pot has to be discarded and replaced, so
if you try to use the pot for too long, you may not get rid
of the gold completely.
Our manufacturing engineering people have developped rules
for how many times you can use the pot before replacement,
and that seems to work as long as it is controlled.
Didier KO4BB
From: "Didier Juges" didier@cox.net
Subject: Re: [time-nuts] HP 5370B low frequency modulation
Date: Thu, 30 Aug 2007 18:10:56 -0500
Message-ID: 061301c7eb5b$063275b0$6501a8c0@didierhp
); SAEximRunCond expanded to false
Errors-To: time-nuts-bounces+magnus=rubidium.dyndns.org@febo.com RETRY
-----Original Message-----
From: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] On Behalf Of Richard
(Rick) Karlquist
Sent: Thursday, August 30, 2007 10:22 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] HP 5370B low frequency modulation
I have heard of assembly lines that do not allow any gold
whatsoever in the building!
That sounds totally unjustified. It's not like gold is going
to jump at the solder joint and contaminate it cold.
The effect of gold contamination is to weaken the joint (the
intermetallic compound of gold and tin is hard and brittle).
Over time, and particularly in high stress environments
(temperature cycling, vibrations), the solder joint
eventually breaks down at the interface and leaves you
with an intermittent connection.
The way we deal with it in the military business (where
temperature cycling and vibration is a way of life) is that
we first remove the gold plating from the solder pin side of
connector pins by tinning the pin a couple of times and each
time sucking the solder with fresh braid or other tool.
That dissolves the gold in solder that is then discarded,
leaving the solder end of the pin free of gold. At that point,
the pin can be soldered normally and the solder joint will show
good characteristics.
Alternately, we use a solder pot and dip the end of the part
that is to be cleaned in it. The problem with that is that
the concentration of gold in the pot increases over time until
the content of the pot has to be discarded and replaced, so
if you try to use the pot for too long, you may not get rid
of the gold completely.
Our manufacturing engineering people have developped rules
for how many times you can use the pot before replacement,
and that seems to work as long as it is controlled.
Even these measures can be argued as overdoing it, even if I understand why
they run popular. The key point is that it is only when the gold concentration
in the solder joint is too high that you start to get these problems. For very
low levels of concentration there is no problem. The issues is really about
how much gold concentration do you end up with and do you have sufficient
control over amount of gold, amont of solder and amount of dissolvement time
for gold to distribute in the tin. These are process control variables.
Cheers,
Magnus
When you solder a connector pin that is gold plated, the concentration of
gold in the immediate vicinity of the interface is maximum, since you go
from pure gold to pure tin/lead and you have all the gradient in-between
because the gold diffuses in the tin, so you will always have an area where
the compound will have the right concentration to cause problem. I have seen
many solder joints contaminated this way and experienced the problem first
hand, it's not just a theoretical problem. Yet, it's quite preventable using
either of these simple methods. As soon as you remove the excess gold, the
concentration drops below the level where it can cause problems and you will
be OK.
I am not aware of a method that does not entail removing the excess gold?
Didier KO4BB
-----Original Message-----
From: Magnus Danielson [mailto:magnus@rubidium.dyndns.org]
Sent: Thursday, August 30, 2007 6:41 PM
To: time-nuts@febo.com; didier@cox.net
Subject: Re: [time-nuts] HP 5370B low frequency modulation
From: "Didier Juges" didier@cox.net
Subject: Re: [time-nuts] HP 5370B low frequency modulation
Date: Thu, 30 Aug 2007 18:10:56 -0500
Message-ID: 061301c7eb5b$063275b0$6501a8c0@didierhp
The effect of gold contamination is to weaken the joint (the
intermetallic compound of gold and tin is hard and brittle).
Over time, and particularly in high stress environments
(temperature
cycling, vibrations), the solder joint eventually breaks
down at the
interface and leaves you with an intermittent connection.
The way we deal with it in the military business (where temperature
cycling and vibration is a way of life) is that we first remove the
gold plating from the solder pin side of connector pins by
tinning the
pin a couple of times and each time sucking the solder with fresh
braid or other tool.
That dissolves the gold in solder that is then discarded,
leaving the
solder end of the pin free of gold. At that point, the pin can be
soldered normally and the solder joint will show good
characteristics.
Alternately, we use a solder pot and dip the end of the
part that is
to be cleaned in it. The problem with that is that the
concentration
of gold in the pot increases over time until the content of the pot
has to be discarded and replaced, so if you try to use the
pot for too
long, you may not get rid of the gold completely.
Our manufacturing engineering people have developped rules for how
many times you can use the pot before replacement, and that
seems to
work as long as it is controlled.
Even these measures can be argued as overdoing it, even if I
understand why they run popular. The key point is that it is
only when the gold concentration in the solder joint is too
high that you start to get these problems. For very low
levels of concentration there is no problem. The issues is
really about how much gold concentration do you end up with
and do you have sufficient control over amount of gold, amont
of solder and amount of dissolvement time for gold to
distribute in the tin. These are process control variables.
Cheers,
Magnus
This is an interesting discussion about gold. Thanks to all
those who have posted. My question is -- I've noticed that
almost all my old HP instruments, from the 60's and some
decades thereafter, use a large amount of gold on all the
PCB traces and many component leads. It gave them a
premium look, even artistic beauty in some cases. I always
assumed it was for performance, reliability, and longevity.
So when was it discovered that using gold was a bad idea?
Is this only for mil-spec stuff or for regular laboratory test
equipment too?
/tvb
My experience is that thermal cycling and vibration exacerbate the problem
very greatly. We have been making both commercial and military products for
a long time, and we started seeing the problem in military products much
before we ever saw it in commercial products.
The intermetallic compound is conductive, so unless you have some mechanical
effect that pushes the conductors apart, the contact will not necessarily be
lost.
Look closely at a PWB that is gold plated (not just the plug-in contact
area, but some older PWBs were entirely gold plated). Look at the interface
where the solder joint meets the gold. On anything that is more than a few
years old, you are likely to see a darker grey ring where the two metals
meet. There you have it. You don't see that on a new board. Remove the
solder from one of these joints with solder wick or a desoldering iron,
clean real good with a small brush and redo the solder joint using a good
cleaning flux, and the solder joint will look normal.
Didier KO4BB
-----Original Message-----
From: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] On Behalf Of Tom Van Baak
Sent: Thursday, August 30, 2007 9:17 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] HP 5370B low frequency modulation, gold
This is an interesting discussion about gold. Thanks to all
those who have posted. My question is -- I've noticed that
almost all my old HP instruments, from the 60's and some
decades thereafter, use a large amount of gold on all the PCB
traces and many component leads. It gave them a premium look,
even artistic beauty in some cases. I always assumed it was
for performance, reliability, and longevity.
So when was it discovered that using gold was a bad idea?
Is this only for mil-spec stuff or for regular laboratory
test equipment too?
/tvb
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