Carbon Comp: Aging Causes Out Of Tol?

[Watson A.Name - \"Watt Su]

I have fifty 910 ohm 1/4W carbon composition resistors, still in the
paper tape, which is labeled:

OHMITE
910 OHM
1/4 W 5%
RC07GF911J
OC9115

Judging from the last line, they're 14 years old. They've never been
used, AKA New Old Stock. Every resistor measures greater than 5%, some
are over 1k. Over 14 years, would drift from aging cause them to go
that far out of tolerance? I have carbon film resistore much older than
these and they still measure within 5% tolerance, usually within 2%.

Thanks.
--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Michael]

"Watson A.Name - \"Watt Sun, the Dark Remover\"" wrote:

I have fifty 910 ohm 1/4W carbon composition resistors, still in the
paper tape, which is labeled:

OHMITE
910 OHM
1/4 W 5%
RC07GF911J
OC9115

Judging from the last line, they're 14 years old. They've never been
used, AKA New Old Stock. Every resistor measures greater than 5%, some
are over 1k. Over 14 years, would drift from aging cause them to go
that far out of tolerance? I have carbon film resistore much older than
these and they still measure within 5% tolerance, usually within 2%.

Thanks.

Do you know their history? Maybe they were out of tolerence at time of
manufacture.

I always heard that carbons change value with humidity. I have many unused
Allen Bradley 5% 1/2W carbons which I took from new stock in the early 70's, and
checking a few of the BROWN-third-band ones at random show all within tolerence.

 

[Watson A.Name - \"Watt Su]

"Michael" <NoSpan@att.net> wrote in message
news:42874D32.71868CB0@att.net...

"Watson A.Name - \"Watt Sun, the Dark Remover\"" wrote:

I have fifty 910 ohm 1/4W carbon composition resistors, still in the
paper tape, which is labeled:

OHMITE
910 OHM
1/4 W 5%
RC07GF911J
OC9115

Judging from the last line, they're 14 years old. They've never
been
used, AKA New Old Stock. Every resistor measures greater than 5%,
some
are over 1k. Over 14 years, would drift from aging cause them to go
that far out of tolerance? I have carbon film resistore much older
than
these and they still measure within 5% tolerance, usually within 2%.

Thanks.


Do you know their history? Maybe they were out of tolerence at time
of
manufacture.

I don't know their history, only that they are still in the tape that
they were in when they came from the factory, with the factory
designation stamped on the tape, so they should be NOS. I've seen tapes
from some place that have various components customized for a stuffing
machine, and this is not one of those.

One would think that it would not be possible for these to be out of tol
when they come from the mfgr, unless there was a major malfunction in
their testing equipment. However, I've heard of such things as
warehouses catching on fire, or goods being shipped in a ship hold next
to a steam boiler, where in either case the goods were exposed to
excessive temperatures. This could have caused some change. But my
experience is that higher temperaturss cause resistors to become lower
resistance.

I always heard that carbons change value with humidity. I have many
unused
Allen Bradley 5% 1/2W carbons which I took from new stock in the early
70's, and
checking a few of the BROWN-third-band ones at random show all within
tolerence.

I checked another bag of loose carbon comp resistors, 6.8 ohm, 1/4W, 5%.
All of them are also greater than 5% out of tolerance, and that is
taking into account the 0.4 ohm resistance of the test leads.

 

[Spehro Pefhany]

On Sun, 15 May 2005 07:50:42 -0700, the renowned "Watson A.Name -
\"Watt Sun, the Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

"Michael" <NoSpan@att.net> wrote in message
news:42874D32.71868CB0@att.net...
"Watson A.Name - \"Watt Sun, the Dark Remover\"" wrote:

I have fifty 910 ohm 1/4W carbon composition resistors, still in the
paper tape, which is labeled:

OHMITE
910 OHM
1/4 W 5%
RC07GF911J
OC9115

Judging from the last line, they're 14 years old. They've never
been
used, AKA New Old Stock. Every resistor measures greater than 5%,
some
are over 1k. Over 14 years, would drift from aging cause them to go
that far out of tolerance? I have carbon film resistore much older
than
these and they still measure within 5% tolerance, usually within 2%.

Thanks.


Do you know their history? Maybe they were out of tolerence at time
of
manufacture.


I don't know their history, only that they are still in the tape that
they were in when they came from the factory, with the factory
designation stamped on the tape, so they should be NOS. I've seen tapes
from some place that have various components customized for a stuffing
machine, and this is not one of those.

One would think that it would not be possible for these to be out of tol
when they come from the mfgr, unless there was a major malfunction in
their testing equipment. However, I've heard of such things as
warehouses catching on fire, or goods being shipped in a ship hold next
to a steam boiler, where in either case the goods were exposed to
excessive temperatures. This could have caused some change. But my
experience is that higher temperaturss cause resistors to become lower
resistance.

I always heard that carbons change value with humidity. I have many
unused
Allen Bradley 5% 1/2W carbons which I took from new stock in the early
70's, and
checking a few of the BROWN-third-band ones at random show all within
tolerence.

I checked another bag of loose carbon comp resistors, 6.8 ohm, 1/4W, 5%.
All of them are also greater than 5% out of tolerance, and that is
taking into account the 0.4 ohm resistance of the test leads.

Maybe your meter needs a new battery? ;-) Long ago I bought a Micronta
DVM for the guys to use in testing product (to replace one they
killed, and needed *now*). I was surprised to find how nonlinear it
was-- a good fraction of 1%, though still within specs-- it had some
crap ASIC that was nowhere near the virtually perfect performance of
the Intersil inspired chips.

There were also problems about 20-30 years ago, well covered in the
trade rags at the time, about out-of-tolerance mil-spec resistors.
Don't recall whether they were film or composition types. It was a bit
of a scandal-- when you pay 20 or 50 times the price, you don't
necessarily expect them to be worse than the standard commercial types
(though it makes sense that problems could crop up due to low-volme
special production arrangements).


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

Yup, carbon composition was notoriously unstable. The phenolic casing was not
hermetic and allowed moisture in and out. About the only way they were better
than carbon film was in power surge rating. A 1 watt could take 5 watts of
overload for a split second without more damage than a small change in value.
Carbon films would flash and flameout.

Also, carbon comps have lower self inductance than carbon film, so you'll
sometimes see them still used in RF power circuits. Sometimes with coils wound
about the body, too.

I remember when Ohmite announced years ago they were ceasing production on their
comps and so many engineers wailed 'No!'. Ohmite relented, but did get to raise
prices.

You may be able to sell them on ebay to people who need replacement parts for
their old gear.


On Sun, 15 May 2005 05:13:49 -0700, "Watson A.Name - \"Watt Sun, the Dark
Remover\"" <NOSPAM@dslextreme.com> wrote:

I have fifty 910 ohm 1/4W carbon composition resistors, still in the
paper tape, which is labeled:

OHMITE
910 OHM
1/4 W 5%
RC07GF911J
OC9115

Judging from the last line, they're 14 years old. They've never been
used, AKA New Old Stock. Every resistor measures greater than 5%, some
are over 1k. Over 14 years, would drift from aging cause them to go
that far out of tolerance? I have carbon film resistore much older than
these and they still measure within 5% tolerance, usually within 2%.

Thanks.

 

[Spehro Pefhany]

On Sun, 15 May 2005 16:08:55 GMT, the renowned
_crusty@ourwonderful.sytes.net wrote:

Yup, carbon composition was notoriously unstable. The phenolic casing was not
hermetic and allowed moisture in and out. About the only way they were better
than carbon film was in power surge rating. A 1 watt could take 5 watts of
overload for a split second without more damage than a small change in value.
Carbon films would flash and flameout.

Also, carbon comps have lower self inductance than carbon film, so you'll
sometimes see them still used in RF power circuits. Sometimes with coils wound
about the body, too.

I remember when Ohmite announced years ago they were ceasing production on their
comps and so many engineers wailed 'No!'. Ohmite relented, but did get to raise
prices.

You may be able to sell them on ebay to people who need replacement parts for
their old gear.

A client says he switched to them for one application because the
extra noise helped an oscillator start reliably. I'm not sure I
believe it was the factor (the parts he got looked just like film
parts to me, with the telltale bulge of crimped endcaps over a tubular
body) but maybe it got the semiconductor maker ********* out of a
possibly litigious bind by killing enough time for another wafer run
to get out.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[mike]

Watson A.Name - \"Watt Sun, the Dark Remover\" wrote:

I have fifty 910 ohm 1/4W carbon composition resistors, still in the
paper tape, which is labeled:

OHMITE
910 OHM
1/4 W 5%
RC07GF911J
OC9115

Judging from the last line, they're 14 years old. They've never been
used, AKA New Old Stock. Every resistor measures greater than 5%, some
are over 1k. Over 14 years, would drift from aging cause them to go
that far out of tolerance? I have carbon film resistore much older than
these and they still measure within 5% tolerance, usually within 2%.

I think this is common.

I bought a box of 1000 114 ohm resistors. Stackpole Mfg Date 1980.
Unfortunately, they're marked 100 Ohm 5%. Was gonna use 'em
in pairs to terminate 50 Ohm transmission lines...oh well...
I should try cooking them to see if they change back.
mike


--
Return address is VALID but some sites block emails
with links. Delete this sig when replying.
..
Wanted, PCMCIA SCSI Card for HP m820 CDRW.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Wanted 12" LCD for Compaq Armada 7770MT.
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/

 

[Walter Harley]

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:118ef69isc5dp88@corp.supernews.com...

Over 14 years, would drift from aging cause them to go
that far out of tolerance?

I was recently working on an amp from the 1950's; every carbon comp in it
was at least 20% higher than its markings indicated.

(Woe be unto the tech who repairs a tube guitar amp and replaces the
resistors with new ones whose values are nominally correct! Depending on
which resistor it is, it'll change the sound of the amp...)

 

[Watson A.Name - \"Watt Su]

"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
news:qtoe815rr9q12qlnntk9co21db4gtc0t1d@4ax.com...

On Sun, 15 May 2005 07:50:42 -0700, the renowned "Watson A.Name -
\"Watt Sun, the Dark Remover\"" <NOSPAM@dslextreme.com> wrote:


"Michael" <NoSpan@att.net> wrote in message
news:42874D32.71868CB0@att.net...
"Watson A.Name - \"Watt Sun, the Dark Remover\"" wrote:

I have fifty 910 ohm 1/4W carbon composition resistors, still in
the
paper tape, which is labeled:

OHMITE
910 OHM
1/4 W 5%
RC07GF911J
OC9115

Judging from the last line, they're 14 years old. They've never
been
used, AKA New Old Stock. Every resistor measures greater than
5%,
some
are over 1k. Over 14 years, would drift from aging cause them to
go
that far out of tolerance? I have carbon film resistore much
older
than
these and they still measure within 5% tolerance, usually within
2%.

Thanks.


Do you know their history? Maybe they were out of tolerence at
time
of
manufacture.


I don't know their history, only that they are still in the tape that
they were in when they came from the factory, with the factory
designation stamped on the tape, so they should be NOS. I've seen
tapes
from some place that have various components customized for a
stuffing
machine, and this is not one of those.

One would think that it would not be possible for these to be out of
tol
when they come from the mfgr, unless there was a major malfunction in
their testing equipment. However, I've heard of such things as
warehouses catching on fire, or goods being shipped in a ship hold
next
to a steam boiler, where in either case the goods were exposed to
excessive temperatures. This could have caused some change. But my
experience is that higher temperaturss cause resistors to become
lower
resistance.

I always heard that carbons change value with humidity. I have
many
unused
Allen Bradley 5% 1/2W carbons which I took from new stock in the
early
70's, and
checking a few of the BROWN-third-band ones at random show all
within
tolerence.

I checked another bag of loose carbon comp resistors, 6.8 ohm, 1/4W,
5%.
All of them are also greater than 5% out of tolerance, and that is
taking into account the 0.4 ohm resistance of the test leads.

Maybe your meter needs a new battery? ;-) Long ago I bought a Micronta
DVM for the guys to use in testing product (to replace one they
killed, and needed *now*). I was surprised to find how nonlinear it
was-- a good fraction of 1%, though still within specs-- it had some
crap ASIC that was nowhere near the virtually perfect performance of
the Intersil inspired chips.

I rechecked a bunch of them with a bench DMM and they're all the same:
5% or more higher than marked. The 6.8 ohms measure 7.2 or more. The
910s measure close to 1k. Usually I measure a 1% precision resistor on
the same range, just to make sure things are working right.

Someone should take the initiative and include a precision resistor in
each DMM, with the two leads sticking out the front. Something similar
to the calibration source that I've seen on the front of decent
o'scopes. A 1% resistor costs only a penny or two.

There were also problems about 20-30 years ago, well covered in the
trade rags at the time, about out-of-tolerance mil-spec resistors.
Don't recall whether they were film or composition types. It was a bit
of a scandal-- when you pay 20 or 50 times the price, you don't
necessarily expect them to be worse than the standard commercial types
(though it makes sense that problems could crop up due to low-volme
special production arrangements).

Reminds me of the 3 foot cat5 patch cords we ordered. Came bagged 50 to
a bag. Supposed to be tested to cat5 specs. I reached in and pulled
out a half dozen with one end bare, no connector. Well, if they really
_were_ tested, they would've caught that 'minor' problem.

Best regards,
Spehro Pefhany
--

 

[Watson A.Name - \"Watt Su]

"Walter Harley" <walterh@cafewalterNOSPAM.com> wrote in message
news:9LednWF97e5xDhrfRVn-pg@speakeasy.net...

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com
wrote
in message news:118ef69isc5dp88@corp.supernews.com...
Over 14 years, would drift from aging cause them to go
that far out of tolerance?

I was recently working on an amp from the 1950's; every carbon comp in
it
was at least 20% higher than its markings indicated.

(Woe be unto the tech who repairs a tube guitar amp and replaces the
resistors with new ones whose values are nominally correct! Depending
on
which resistor it is, it'll change the sound of the amp...)

For the old toob amps., 20% wasn't all that disastrous. As long as the
change wasn't caused by heat. Since those amps get hot, the half watt
resistor is probably only capable of dissipating half that, because it's
in a hot environment. Could be that the vents were inadequate or were
plugged up with dust and spider webs.

 

[Watson A.Name - \"Watt Su]

"mike" <spamme0@netscape.net> wrote in message
news:4287F5D1.5040107@netscape.net...

Watson A.Name - \"Watt Sun, the Dark Remover\" wrote:
"mike" <spamme0@netscape.net> wrote in message
news:428785D4.8000206@netscape.net...

Watson A.Name - \"Watt Sun, the Dark Remover\" wrote:

I have fifty 910 ohm 1/4W carbon composition resistors, still in
the
paper tape, which is labeled:

OHMITE
910 OHM
1/4 W 5%
RC07GF911J
OC9115

Judging from the last line, they're 14 years old. They've never

been

used, AKA New Old Stock. Every resistor measures greater than 5%,

some

are over 1k. Over 14 years, would drift from aging cause them to
go
that far out of tolerance? I have carbon film resistore much older

than

these and they still measure within 5% tolerance, usually within
2%.


I think this is common.
I bought a box of 1000 114 ohm resistors. Stackpole Mfg Date 1980.
Unfortunately, they're marked 100 Ohm 5%. Was gonna use 'em
in pairs to terminate 50 Ohm transmission lines...oh well...
I should try cooking them to see if they change back.
mike


Hey, YEAH! Great idea! I'll hold a couple over the soldering iron
and
see if they stay changed when they cool off. It won't hurt to mess
up a
few, since they're already messed up to begin with. ;-)

BRB...

Well, that didn't help. I took four of them and layed each on the
soldering iron. Each went up several dozen ohme, some between 1050
and
1100. And they stayed at that value when cool. :-(

Don't think that works. Need to use low heat for long term. Put some
atop that big CRT monitor for a few weeks. Mine's hot enough to bake
bread. ;-)

I've got a LCD panel, doesn't get warm. :-(

There's another issue that comes to play on older resistors.
Back in the day, they cranked out resistors and marked 'em whatever
they
measured. 5% resistors were selected out. Then the 10%ers. What was
left was 20%. End result was that a 20% resistor was hardly ever
within 10%. For each tolerance, you got a bi-modal distribution
with a hole where the good stuff was taken out.
mike

Yeah, I've seen that with some parts. Sucks big time if you're
depending on getting good parts. Thanks.

 

[Watson A.Name - \"Watt Su]

"Jim Adney" <jadney@vwtype3.org> wrote in message
news:8vvf819a1qo9d84a9c4kqggcjumo2pg0hc@4ax.com...

On Sun, 15 May 2005 05:13:49 -0700 "Watson A.Name - \"Watt Sun, the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

I have fifty 910 ohm 1/4W carbon composition resistors, still in the
paper tape, which is labeled:

OHMITE
910 OHM
1/4 W 5%
RC07GF911J
OC9115

Judging from the last line, they're 14 years old. They've never been
used, AKA New Old Stock. Every resistor measures greater than 5%,
some
are over 1k. Over 14 years, would drift from aging cause them to go
that far out of tolerance? I have carbon film resistore much older
than
these and they still measure within 5% tolerance, usually within 2%.

If you could find an old Allen-Bradley catalog you'd be truly amazed
at the amount of detail they lay out on the moisture sensitivity of
these resistors.

The gist of it is as follows:

1) Carbon composition resistors will absorb moisture out of the air
and go up in resistance. If the resistance is important to the
manufacturer, they much keep them in a special dry engvironment, just
like flux coated welding rods.

2) If you have carbon composition resistors which have gotten damp,
they can be dryed out by heating them to temps below 100C for several
days. 2 Watters take longer than 1/4 Watters. Don't try to speed this
up by using higher temps.

3) If you solder them when they are "damp" the change in resistance
will be locked in, ie no longer reversible.

Thanks for the info. The four I put on the soldering iron were probably
overheated and won't be salvageable. The rest haven't been exposed to
water or high humidity, generally it's low humidity most of the time
here. So I don't see why they could've changed. I'm thinking that I
might be able to put them inside a ziplock bag with a dessicant and
leave them out in the sun for awhile, and it might help. Can't hurt
much since they're already nearly worthless.

I did this test on a batch of 27k, 2W carbon comp resistors a number
of years ago. They were all high, and most of them were out of
tolerance, this was immediately as purchased from Newark. But they all
came back into tolerance after heating in my home-made oven for about
a week.

But at what temperature? I've got a bunch of old 1- and 2-watt
resistors and I don't think I'll ever use them because I'll never need a
(for example) 27k 2W resistor since it takes a couple hundred volts to
get up to 2W and I don't do tubes anymore.

> -

 

[Jim Adney]

On Mon, 16 May 2005 18:30:32 -0700 "Watson A.Name - \"Watt Sun, the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

Thanks for the info. The four I put on the soldering iron were probably
overheated and won't be salvageable. The rest haven't been exposed to
water or high humidity, generally it's low humidity most of the time
here. So I don't see why they could've changed. I'm thinking that I
might be able to put them inside a ziplock bag with a dessicant and
leave them out in the sun for awhile, and it might help. Can't hurt
much since they're already nearly worthless.

I don't think it takes anything extreme to make this moisture
absorption happen. Try baking them. I think you'll be surprised.

I did this test on a batch of 27k, 2W carbon comp resistors a number
of years ago. They were all high, and most of them were out of
tolerance, this was immediately as purchased from Newark. But they all
came back into tolerance after heating in my home-made oven for about
a week.

But at what temperature? I've got a bunch of old 1- and 2-watt
resistors and I don't think I'll ever use them because I'll never need a
(for example) 27k 2W resistor since it takes a couple hundred volts to
get up to 2W and I don't do tubes anymore.

I wrapped them up in alum foil with a 25W light bulb and stuck them in
a metal wastebasket for a week. As an experiment, I actually took them
out once a day and measured R for each one every day and recorded it.
I suspect the temps were 150-175F. This reduces the RELATIVE humidity
to something really small. A dessicant would do the same thing, but
the heat increases the mobility of the absorbed water, so it's much
more effective.

In a week's time, each resistor was back within tolerance.

As I noted before, however, this will not work with resistors which
have been heated to soldering temps. Allen-Bradley did not explain the
mechanism for this and I don't have any idea what it might be.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

 

[Watson A.Name - \"Watt Su]

"Jim Adney" <jadney@vwtype3.org> wrote in message
news:updl81581c9s35fhishf8g02lj0ghd2hvi@4ax.com...

On Mon, 16 May 2005 18:30:32 -0700 "Watson A.Name - \"Watt Sun, the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

Thanks for the info. The four I put on the soldering iron were
probably
overheated and won't be salvageable. The rest haven't been exposed
to
water or high humidity, generally it's low humidity most of the time
here. So I don't see why they could've changed. I'm thinking that I
might be able to put them inside a ziplock bag with a dessicant and
leave them out in the sun for awhile, and it might help. Can't hurt
much since they're already nearly worthless.

I don't think it takes anything extreme to make this moisture
absorption happen. Try baking them. I think you'll be surprised.

I did this test on a batch of 27k, 2W carbon comp resistors a
number
of years ago. They were all high, and most of them were out of
tolerance, this was immediately as purchased from Newark. But they
all
came back into tolerance after heating in my home-made oven for
about
a week.

But at what temperature? I've got a bunch of old 1- and 2-watt
resistors and I don't think I'll ever use them because I'll never
need a
(for example) 27k 2W resistor since it takes a couple hundred volts
to
get up to 2W and I don't do tubes anymore.

I wrapped them up in alum foil with a 25W light bulb and stuck them in
a metal wastebasket for a week. As an experiment, I actually took them
out once a day and measured R for each one every day and recorded it.
I suspect the temps were 150-175F. This reduces the RELATIVE humidity
to something really small. A dessicant would do the same thing, but
the heat increases the mobility of the absorbed water, so it's much
more effective.

In a week's time, each resistor was back within tolerance.

As I noted before, however, this will not work with resistors which
have been heated to soldering temps. Allen-Bradley did not explain the
mechanism for this and I don't have any idea what it might be.

Well, thanks for the info. It seems that the resistors were made for
tube equipment. The insides of a toob chassis get nice and warm, and
would cook the moisture out of the resistors. Except almost all of the
equipment nowadays is not toob and doesn't get that hot inside.

I found a bag of at least a hundred 56k, 1/2W resistors that are the
same way. I think I'll put the whole bunch into a 'hot box'.
It puzzles me why it should take so long. Maybe the resistors are
coated with something to make them moistureproof, and it's just not
perfect, and lets in the moisture over the years. But when I think
about it, having it take years to get that way, it's really not that bad
having to wait only a week to fix it.

> -

 

[mike]

Watson A.Name - \"Watt Sun, the Dark Remover\" wrote:

"mike" <spamme0@netscape.net> wrote in message
news:428785D4.8000206@netscape.net...

Watson A.Name - \"Watt Sun, the Dark Remover\" wrote:

I have fifty 910 ohm 1/4W carbon composition resistors, still in the
paper tape, which is labeled:

OHMITE
910 OHM
1/4 W 5%
RC07GF911J
OC9115

Judging from the last line, they're 14 years old. They've never

been

used, AKA New Old Stock. Every resistor measures greater than 5%,

some

are over 1k. Over 14 years, would drift from aging cause them to go
that far out of tolerance? I have carbon film resistore much older

than

these and they still measure within 5% tolerance, usually within 2%.


I think this is common.
I bought a box of 1000 114 ohm resistors. Stackpole Mfg Date 1980.
Unfortunately, they're marked 100 Ohm 5%. Was gonna use 'em
in pairs to terminate 50 Ohm transmission lines...oh well...
I should try cooking them to see if they change back.
mike


Hey, YEAH! Great idea! I'll hold a couple over the soldering iron and
see if they stay changed when they cool off. It won't hurt to mess up a
few, since they're already messed up to begin with. ;-)

BRB...

Well, that didn't help. I took four of them and layed each on the
soldering iron. Each went up several dozen ohme, some between 1050 and
1100. And they stayed at that value when cool. :-(

Don't think that works. Need to use low heat for long term. Put some
atop that big CRT monitor for a few weeks. Mine's hot enough to bake
bread. ;-)

There's another issue that comes to play on older resistors.
Back in the day, they cranked out resistors and marked 'em whatever they
measured. 5% resistors were selected out. Then the 10%ers. What was
left was 20%. End result was that a 20% resistor was hardly ever
within 10%. For each tolerance, you got a bi-modal distribution
with a hole where the good stuff was taken out.
mike

Just put a 470 ohm resistor in parallel with the two 114 ohms, and
you'll have 50.8 ohms, which is just about right.

Long ago, in a galaxy far, far away, I scrounged a dummy load out of a
cardboard store display for a CB xcvr. They used a 50 ohm 5W wirewound
resistor, and put a capacitor, I think it was 47 pF, in series to series
resonate with the wirewound resistor's inductance and cancel it out.
Worked just fine.


--

--
Return address is VALID but some sites block emails
with links. Delete this sig when replying.
..
Wanted, PCMCIA SCSI Card for HP m820 CDRW.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Wanted 12" LCD for Compaq Armada 7770MT.
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/

 

[Jim Adney]

On Sun, 15 May 2005 05:13:49 -0700 "Watson A.Name - \"Watt Sun, the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

I have fifty 910 ohm 1/4W carbon composition resistors, still in the
paper tape, which is labeled:

OHMITE
910 OHM
1/4 W 5%
RC07GF911J
OC9115

Judging from the last line, they're 14 years old. They've never been
used, AKA New Old Stock. Every resistor measures greater than 5%, some
are over 1k. Over 14 years, would drift from aging cause them to go
that far out of tolerance? I have carbon film resistore much older than
these and they still measure within 5% tolerance, usually within 2%.

If you could find an old Allen-Bradley catalog you'd be truly amazed
at the amount of detail they lay out on the moisture sensitivity of
these resistors.

The gist of it is as follows:

1) Carbon composition resistors will absorb moisture out of the air
and go up in resistance. If the resistance is important to the
manufacturer, they much keep them in a special dry engvironment, just
like flux coated welding rods.

2) If you have carbon composition resistors which have gotten damp,
they can be dryed out by heating them to temps below 100C for several
days. 2 Watters take longer than 1/4 Watters. Don't try to speed this
up by using higher temps.

3) If you solder them when they are "damp" the change in resistance
will be locked in, ie no longer reversible.


I did this test on a batch of 27k, 2W carbon comp resistors a number
of years ago. They were all high, and most of them were out of
tolerance, this was immediately as purchased from Newark. But they all
came back into tolerance after heating in my home-made oven for about
a week.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

 

[Jim Adney]

On Tue, 17 May 2005 23:30:49 -0700 "Watson A.Name - \"Watt Sun, the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

Well, thanks for the info. It seems that the resistors were made for
tube equipment. The insides of a toob chassis get nice and warm, and
would cook the moisture out of the resistors. Except almost all of the
equipment nowadays is not toob and doesn't get that hot inside.

The tube connection is a very good point. I often think about letting
my old tube gear just warm up occasionally to drive off the
accumulated moisture, but I'm still not likely to leave any of them on
for a week. Of course if I used that gear every day everything would
probably be fine.

I found a bag of at least a hundred 56k, 1/2W resistors that are the
same way. I think I'll put the whole bunch into a 'hot box'.
It puzzles me why it should take so long. Maybe the resistors are
coated with something to make them moistureproof, and it's just not
perfect, and lets in the moisture over the years. But when I think
about it, having it take years to get that way, it's really not that bad
having to wait only a week to fix it.

It can be surprising how long it can take to drive off moisture. In
vacuum systems, we will sometimes bake a stainless steel tube to 200C
for several hours in order to produce the best possible vacuum.
Moisture is not the only thing that's being driven off, but it's the
main one, and that's just from a "clean" metal surface.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

 

[Watson A.Name - \"Watt Su]

"mike" <spamme0@netscape.net> wrote in message
news:428785D4.8000206@netscape.net...

Watson A.Name - \"Watt Sun, the Dark Remover\" wrote:
I have fifty 910 ohm 1/4W carbon composition resistors, still in the
paper tape, which is labeled:

OHMITE
910 OHM
1/4 W 5%
RC07GF911J
OC9115

Judging from the last line, they're 14 years old. They've never
been
used, AKA New Old Stock. Every resistor measures greater than 5%,
some
are over 1k. Over 14 years, would drift from aging cause them to go
that far out of tolerance? I have carbon film resistore much older
than
these and they still measure within 5% tolerance, usually within 2%.

I think this is common.
I bought a box of 1000 114 ohm resistors. Stackpole Mfg Date 1980.
Unfortunately, they're marked 100 Ohm 5%. Was gonna use 'em
in pairs to terminate 50 Ohm transmission lines...oh well...
I should try cooking them to see if they change back.
mike

Hey, YEAH! Great idea! I'll hold a couple over the soldering iron and
see if they stay changed when they cool off. It won't hurt to mess up a
few, since they're already messed up to begin with. ;-)

BRB...

Well, that didn't help. I took four of them and layed each on the
soldering iron. Each went up several dozen ohme, some between 1050 and
1100. And they stayed at that value when cool. :-(

Just put a 470 ohm resistor in parallel with the two 114 ohms, and
you'll have 50.8 ohms, which is just about right.

Long ago, in a galaxy far, far away, I scrounged a dummy load out of a
cardboard store display for a CB xcvr. They used a 50 ohm 5W wirewound
resistor, and put a capacitor, I think it was 47 pF, in series to series
resonate with the wirewound resistor's inductance and cancel it out.
Worked just fine.

> --

 

[Ken Finney]

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:118f8qbc5pepsc4@corp.supernews.com...

"mike" <spamme0@netscape.net> wrote in message
news:428785D4.8000206@netscape.net...
Watson A.Name - \"Watt Sun, the Dark Remover\" wrote:
I have fifty 910 ohm 1/4W carbon composition resistors, still in the
paper tape, which is labeled:

OHMITE
910 OHM
1/4 W 5%
RC07GF911J
OC9115

Judging from the last line, they're 14 years old. They've never
been
used, AKA New Old Stock. Every resistor measures greater than 5%,
some
are over 1k. Over 14 years, would drift from aging cause them to go
that far out of tolerance? I have carbon film resistore much older
than
these and they still measure within 5% tolerance, usually within 2%.

I think this is common.
I bought a box of 1000 114 ohm resistors. Stackpole Mfg Date 1980.
Unfortunately, they're marked 100 Ohm 5%. Was gonna use 'em
in pairs to terminate 50 Ohm transmission lines...oh well...
I should try cooking them to see if they change back.
mike

Hey, YEAH! Great idea! I'll hold a couple over the soldering iron and
see if they stay changed when they cool off. It won't hurt to mess up a
few, since they're already messed up to begin with. ;-)

BRB...

Well, that didn't help. I took four of them and layed each on the
soldering iron. Each went up several dozen ohme, some between 1050 and
1100. And they stayed at that value when cool. :-(

< snip >

It's been a long time since I did the math, but IIRC, when you added up all
the tolerances, milspec carbon comps could vary in-circuit by 41.4% of their
stated value and still be within spec.



#! rnews 1806
Xref: xyzzy rec.arts.sf.written:1083035
Newsgroups: rec.arts.sf.written
Path: xyzzy!nntp
From: Eric D. Berge <eric_berge @ hotmail.com.invalid>
Subject: Re: Robert E Lee
X-Nntp-Posting-Host: anc659yt31.sw.nos.boeing.com
Content-Type: text/plain; charset=us-ascii
Message-ID: <t4mh811dfpoovndsbn4echbhct23ldrl01@4ax.com>
Sender: nntp@news.boeing.com (Boeing NNTP News Access)
Content-Transfer-Encoding: 7bit
Organization: The Boeing Company
X-Newsreader: Forte Agent 1.8/32.548
References: <d5hnof022d4@news2.newsguy.com> <1115513667.028875.111570@z14g2000cwz.googlegroups.com> <lq2q715c3lk16q2glb35vhfl876vkdo1rm@4ax.com> <1115566289.589325.125230@g14g2000cwa.googlegroups.com> <1115574033.914852.295940@f14g2000cwb.googlegroups.com> <1115829968.729892.209590@o13g2000cwo.googlegroups.com> <8ek5815s767r0ggh592ujghq5orjut8k65@4ax.com> <D4qdnReuEbCmkBjfRVn-pQ@comcast.com> <1116024709.700635.252180@f14g2000cwb.googlegroups.com>
Mime-Version: 1.0
Date: Mon, 16 May 2005 17:55:33 GMT

On 13 May 2005 15:51:49 -0700, "stevem@citlink.net"
<stevenm@uneedspeed.net> wrote:

None of the South's better generals, however, fought to preserve
slavery. Niether Robert E. Lee nor Stonewall Jackson, nor Jeb Stuart,
nor George Johnston were slave owners.

Is that right? How do you account for this:
http://www.sonofthesouth.net/leefoundation/lees%20slave.htm

I can't find anything in a cursory online search about Jackson owning
slaves, but his family certainly did:
http://en.wikipedia.org/wiki/Stonewall_Jackson

....as was JEB Stuart: http://www.jebstuart.org/history.cfm

Don't know George Johnston. If you mean Joe Johnston, I can't find
anything online with another cursory search. Not going to try very
hard; the side he picked speaks for itself.

They thought the institution abhorent.

Obviously not.

 

[tlbs]

These resistors were manufactured to the military specification
MIL-R-11, which was cancelled in 1997. I do not have access to the
historical document. However, a similar specification for established
reliability carbon-comp resistors is available here:

http://www.dscc.dla.mil/Downloads/MilSpec/Docs/MIL-R-39008/mil39008.pdf

The moisture, lifetime, aging, etc. for an RCR07 should be very similar
to an RC07.