?? I may be wrong about the voltage value, I am going by memory
of the advertising.
?? I have wondered the same thing about the oil filling. Its
possible the casings were cast and the winding inserted in it. I
don't think the windings were deliberately misshapen? but that
might be. I wonder what effect squeezing them would have on the
value. If the spacing remained constant the shape would have
little effect. My own experience in manufacturing is with
precision resistors, I have little idea how capacitors were made.
?? BTW, the Micamold paper caps seem to have a terrible
reputation. Every one I've encountered was very leaky but they
look find inside. Same with the Solar flat paper caps.
?? Both of these companies vanished shortly after WW-2, I have
never been able to find out what happened. Solar had space
reserved in an early "Radio's Master" catalog but no entry and
the next issue just was not there.
?? I've never seen any Micamold caps in -hp- stuff but lots of
Sprague, they must have had something going for them.

On 11/5/2021 9:11 PM, Chuck Harris wrote:

Hi Richard,

Bumble bee was a descriptive name based on the colorful
bands used to indicate the capacitor's value and voltage
rating. It was certainly not a brand name.

Tektronix used numerous 400V oil filled versions of this
capacitor. I replaced several dozen in my 513D, so I am
certain that your statement about the 650V version being
the only oil version is incorrect. The 400V rating is one
of the yellow bands that makes it look like a bumble bee.

Every one that I replaced had the oil filler tube.

I have observed that the capacitor "slug" is smaller than
the cavity that it fits into. It had to be, or they would
not have been able to fill the capacitor with oil from the
tube on the end. How did they make that cavity?

It is my impression that if the slug was misshapen, it most
probably was built that way. Perhaps to keep it from rattling
about in the larger cavity that it fit into.

Excepting where the solder sealed filler tube was damaged during
the capacitor's installation, oil filled BB's lasted a very long
time... easily more than 10 years. The ordinary beeswax dipped
paper capacitors became leaky after a year or two.

-Chuck Harris


On Fri, 5 Nov 2021 15:50:59 -0700 "Richard Knoppow"
<dickburk@...> wrote:

??? I want to respond to a couple of things in this thread.
First of all, there were other brands of molded paper caps. None
of these had the consistent problems of the Sprague caps of
cracking and actually breaking. Also, I have disected number of
failed plastic caps but don't see the distorted windings in
others. Something went very wrong with these. The early caps were
coded with the JAN striped coding, hence the name "Bumble Bee".
The actual brand name was Black Beauty. The 650V versions were
the oil filled ones, lower voltage were not oil filled. The oil
filled caps are often found with the oil leaked out. The failure
seems to be the seal of the filler tube. The tube was also the
lead on one side having a wire soldered (maybe welded) into it.
If the seal is disturbed by, for instance, excessive soldering
temperature, the oil will leak out. The SP-600 seems to have had
an especial problem with this.
?? Also, the property of dielectric absorption, which causes a
capacitor to retain some charge after being discharged, can be a
problem with timing and low frequency circuits. One of the few
virtues of paper capacitors is low dielectric absorption. They
are a better choice than mica and much better than HI-K ceramic
caps. Plastic film caps, particularly of certain types have
practically no DA and are the best choice. I don't think the
Black Beauty caps were particularly low in DA but all paper caps
are pretty good.
?? The Black Beauty line was advertised as a long life, high
quality brand. I think Sprague may have fixed the problems with
them eventually but they got a bad reputation quickly. Hammarlund
went to all ceramic caps and at least military SP-600's were
modified to replace all of the paper caps with ceramic ones.
Those are pretty much trouble free.
?? Whatever happened it caused physical distortion of the
windings of the caps. That could have come from shrinkage of the
case material as it cooled. It seems to be in both the oil filled
and non filled versions, at least the ones I've dissected.
On 11/5/2021 7:25 AM, greenboxmaven via groups.io wrote:

Thanks for this very good explanation. In addition to the
points you made, I have read the oil fill was often complete,
and hydrostatic force would test the integrety of the plastic.
Shrinkage and loss of resilience of the case would increase the
chance of cracks and leaks. The late 1940s is a fascinating
time in history for me. There was a great deal of technological
progress made, often with over confidence in new materials? and
techniques inspired by wartime successes that performed very
well in the short term but lacked long term reliability. The
"Bumble Bee" condensers were excellent in one regard- they had
very little residual charge in the dielectric after being fully
discharged. When used as a coupling condenser, that can make a
difference.

??? Bruce Gentry, KA2IVY



On 11/5/21 9:38, Chuck Harris wrote:

BB capacitors were molded as well as the technology of the day
would allow... That is not why they cracked.

The problem is the plastic they used, like most plastics, shrinks
slowly over time, and the wire leads, and especially the solder
sealed oil filler tube, that penetrate the plastic, don't.

This can cause a crack to form at the weakest point, which is
usually at the mold line formed by slight misalignment of the
mold halves.

When you injection mold plastic, the plastic's internal bonds
stretch out to fill the mold. When the plastic cools, it is
frozen into a state where those bonds are stretched.

Over time, under the continuous stress of these stretched bonds,
the plastic will cold flow into a more relaxed state... becoming
slightly smaller.

The problem is if the plastic is constrained by something inside
of it that cannot shrink.... such as the wire leads, a gear's
hub, or an oil filler tube, something has to give.

If the plastic shrinks around a metal tube, the thickest parts of
the plastic will break the thinest parts forming a crack, and a
leak.

I was told by Deane Kidd, that in the early days, Tektronix
created a situation, ripe for failure with BB capacitors, by
putting them tightly fitted into ceramic or bakelite terminal
strips. When the capacitor's leads were soldered, the heat
traveling down the very short leads would melt the capacitor's
solder seal, allowing the oil to mix with the solder, and make a
leak. In the worst cases, the oil would drool out leaving the
capacitor incapable of withstanding its rated voltage.

Not to mention it made a greasy dirty mess in their otherwise
very nice looking scopes.

-Chuck Harris

On Thu, 4 Nov 2021 14:40:42 -0400 "greenboxmaven via groups.io"
<ka2ivy@...> wrote:

Sprague "Bumble Bee" and "Black Beauty" condensers were molded
improperly, and they will crack, especially the oil filled ones,
and let in moisture. That seems to react with the oil and make
it conductive as well as corrosive. Once this happens, leakage
gets very bad, especially when the condenser is heated by
surrounding components. Many efforts have been made to bake
and otherwise restore them, but once the problem begins it can
not be reversed. The dielectric charicteristic? is perported to
be superb for audio circuits, and AudioPhools will freak out if
these condensers are replaced, that is until the power
transformer, rectifer, output tubes, and filter choke in their
amplifiers are all incinerated. Not only did Hammarlund use
them in receivers, Collins and National did as well. Tektronix
used them in their equipment, and too many consumer electronics
companies to recall all of them.

?? Bruce Gentry, KA2IVY

On 11/4/21 13:45, Richard Knoppow wrote:

Who made those? Some early advertising for Sprague Black Beauty
caps said they were plasticized paper. The main problem with
these is some sort of production problem they had. I have
dissected a number of "bumble bee" caps, these are actually
Sprague Black Beauty caps with striped value markigns. I found
the windings were distorted. I suspect this happened during the
encapsulation but don't know. Some of these caps, the higher
voltage ones, were oil impregnated. The oil was introduced
through a tube which formed one of the leads. It is common for
all the oil to have leaked out due to a lack of sealing at the
solder joint between the tube and the lead. That may have been
due to excessive heat when the caps were installed. The most
notorious of the BB caps are those in the Hammarlund SP-600,
however, they were very widely used including in a lot of -hp-
gear. However, in the receiver it is common to find cracked or
split caps or even caps where part of the casing has come off.
I have not seen that in any other make of equipment. Perhaps
just a bad lot or perhaps some difference in installation.
Nonetheless, ALL paper caps become degraded with age. The usual
symptom is an increase in series resistance. Leakage, which is
another term for parallel resistance, is sometimes a problem
but not as often. I don't think any of these caps, even the
real oil filled transmitting caps, was intended to have a
lifetime of over about ten years. The life problem was known
and described in some engineering texts. It was dependent
partly on voltage; the closer the voltage to the rated voltage
the shorter the life of the cap. Likely it was some sort of
electrolytic degradation of the paper. In any case, paper caps
should be replaced with modern plastic film caps. These for
the most part will last forever and generally will improve
performance perhaps beyond the original. There is a good
amount of information on the web about the relative merits of
various kinds of plastic dielectrics. Polypropylene seems to
be about the best especially for RF use.

On 11/4/2021 9:33 AM, Dave Wise wrote:

Even the later plasticized-paper “Prokar” and “DiFilm”
versions can cause trouble in some applications – they may
not be leaky, but their Dielectric Absorption and Dissipation
Factor are “through the roof”.

Dave Wise

*From:*HP-Agilent-Keysight-equipment@groups.io
[mailto:HP-Agilent-Keysight-equipment@groups.io] *On Behalf Of
*greenboxmaven via groups.io
*Sent:* Thursday, November 04, 2021 6:25 AM
*To:*HP-Agilent-Keysight-equipment@groups.io
*Subject:* Re: [HP-Agilent-Keysight-equipment] HP200CD
oscillator

ALL Sprague "Black Cat", "Black Beauty" and? color striped
"Bumble Bee" condensers should be considered bad on sight.
Unfortunately, they are common in older equipment of all makes
and models. The 630V. polyester condensers are a fine
replacement. The only condensers that are polarized are
electrolytics, poyester condensers are not polarized.

??? Bruce Gentry, KA2IVY

On 11/4/21 8:51, Richard Merifield wrote:

??? My unit has Black Cat 0.5MFD 400v axial capacitors for
C8 and C9. Would 630v polyester unpolarised caps be ok
??? replacements?

开云体育

??? I want to respond to a couple of things in this thread.
First of all, there were other brands of molded paper caps. None
of these had the consistent problems of the Sprague caps of
cracking and actually breaking. Also, I have disected number of
failed plastic caps but don't see the distorted windings in
others. Something went very wrong with these. The early caps were
coded with the JAN striped coding, hence the name "Bumble Bee".
The actual brand name was Black Beauty. The 650V versions were
the oil filled ones, lower voltage were not oil filled. The oil
filled caps are often found with the oil leaked out. The failure
seems to be the seal of the filler tube. The tube was also the
lead on one side having a wire soldered (maybe welded) into it.
If the seal is disturbed by, for instance, excessive soldering
temperature, the oil will leak out. The SP-600 seems to have had
an especial problem with this.
?? Also, the property of dielectric absorption, which causes a
capacitor to retain some charge after being discharged, can be a
problem with timing and low frequency circuits. One of the few
virtues of paper capacitors is low dielectric absorption. They
are a better choice than mica and much better than HI-K ceramic
caps. Plastic film caps, particularly of certain types have
practically no DA and are the best choice. I don't think the
Black Beauty caps were particularly low in DA but all paper caps
are pretty good.
?? The Black Beauty line was advertised as a long life, high
quality brand. I think Sprague may have fixed the problems with
them eventually but they got a bad reputation quickly. Hammarlund
went to all ceramic caps and at least military SP-600's were
modified to replace all of the paper caps with ceramic ones.
Those are pretty much trouble free.
?? Whatever happened it caused physical distortion of the
windings of the caps. That could have come from shrinkage of the
case material as it cooled. It seems to be in both the oil filled
and non filled versions, at least the ones I've dissected.
On 11/5/2021 7:25 AM, greenboxmaven via groups.io wrote:

Thanks for this very good explanation. In addition to the
points you made, I have read the oil fill was often complete,
and hydrostatic force would test the integrety of the plastic.
Shrinkage and loss of resilience of the case would increase the
chance of cracks and leaks. The late 1940s is a fascinating
time in history for me. There was a great deal of technological
progress made, often with over confidence in new materials? and
techniques inspired by wartime successes that performed very
well in the short term but lacked long term reliability. The
"Bumble Bee" condensers were excellent in one regard- they had
very little residual charge in the dielectric after being fully
discharged. When used as a coupling condenser, that can make a
difference.

??? Bruce Gentry, KA2IVY



On 11/5/21 9:38, Chuck Harris wrote:

BB capacitors were molded as well as the technology of the day
would allow... That is not why they cracked.

The problem is the plastic they used, like most plastics, shrinks
slowly over time, and the wire leads, and especially the solder
sealed oil filler tube, that penetrate the plastic, don't.

This can cause a crack to form at the weakest point, which is
usually at the mold line formed by slight misalignment of the
mold halves.

When you injection mold plastic, the plastic's internal bonds
stretch out to fill the mold. When the plastic cools, it is
frozen into a state where those bonds are stretched.

Over time, under the continuous stress of these stretched bonds,
the plastic will cold flow into a more relaxed state... becoming
slightly smaller.

The problem is if the plastic is constrained by something inside of
it that cannot shrink.... such as the wire leads, a gear's hub,
or an oil filler tube, something has to give.

If the plastic shrinks around a metal tube, the thickest parts of
the plastic will break the thinest parts forming a crack, and a
leak.

I was told by Deane Kidd, that in the early days, Tektronix created
a situation, ripe for failure with BB capacitors, by putting them
tightly fitted into ceramic or bakelite terminal strips. When the
capacitor's leads were soldered, the heat traveling down the very
short leads would melt the capacitor's solder seal, allowing the
oil to mix with the solder, and make a leak. In the worst cases,
the oil would drool out leaving the capacitor incapable of
withstanding its rated voltage.

Not to mention it made a greasy dirty mess in their otherwise very
nice looking scopes.

-Chuck Harris

On Thu, 4 Nov 2021 14:40:42 -0400 "greenboxmaven via groups.io"
<ka2ivy@...> wrote:

Sprague "Bumble Bee" and "Black Beauty" condensers were molded
improperly, and they will crack, especially the oil filled ones,
and let in moisture. That seems to react with the oil and make it
conductive as well as corrosive. Once this happens, leakage gets
very bad, especially when the condenser is heated by surrounding
components. Many efforts have been made to bake? and otherwise
restore them, but once the problem begins it can not be reversed.
The dielectric charicteristic? is perported to be superb for audio
circuits, and AudioPhools will freak out if these condensers are
replaced, that is until the power transformer, rectifer, output
tubes, and filter choke in their amplifiers are all incinerated.
Not only did Hammarlund use them in receivers, Collins and
National did as well. Tektronix used them in their equipment, and
too many consumer electronics companies to recall all of them.

?? Bruce Gentry, KA2IVY

On 11/4/21 13:45, Richard Knoppow wrote:

Who made those? Some early advertising for Sprague Black Beauty
caps said they were plasticized paper. The main problem with
these is some sort of production problem they had. I have
dissected a number of "bumble bee" caps, these are actually
Sprague Black Beauty caps with striped value markigns. I found
the windings were distorted. I suspect this happened during the
encapsulation but don't know. Some of these caps, the higher
voltage ones, were oil impregnated. The oil was introduced
through a tube which formed one of the leads. It is common for
all the oil to have leaked out due to a lack of sealing at the
solder joint between the tube and the lead. That may have been
due to excessive heat when the caps were installed. The most
notorious of the BB caps are those in the Hammarlund SP-600,
however, they were very widely used including in a lot of -hp-
gear. However, in the receiver it is common to find cracked or
split caps or even caps where part of the casing has come off. I
have not seen that in any other make of equipment. Perhaps just
a bad lot or perhaps some difference in installation.
Nonetheless, ALL paper caps become degraded with age. The usual
symptom is an increase in series resistance. Leakage, which is
another term for parallel resistance, is sometimes a problem but
not as often. I don't think any of these caps, even the real oil
filled transmitting caps, was intended to have a lifetime of
over about ten years. The life problem was known and described
in some engineering texts. It was dependent partly on voltage;
the closer the voltage to the rated voltage the shorter the life
of the cap. Likely it was some sort of electrolytic degradation
of the paper. In any case, paper caps should be replaced with
modern plastic film caps. These for the most part will last
forever and generally will improve performance perhaps beyond
the original. There is a good amount of information on the web
about the relative merits of various kinds of plastic
dielectrics. Polypropylene seems to be about the best especially
for RF use.

On 11/4/2021 9:33 AM, Dave Wise wrote:

Even the later plasticized-paper “Prokar” and “DiFilm” versions
can cause trouble in some applications – they may not be leaky,
but their Dielectric Absorption and Dissipation Factor are
“through the roof”.

Dave Wise

*From:*HP-Agilent-Keysight-equipment@groups.io
[mailto:HP-Agilent-Keysight-equipment@groups.io] *On Behalf Of
*greenboxmaven via groups.io
*Sent:* Thursday, November 04, 2021 6:25 AM
*To:*HP-Agilent-Keysight-equipment@groups.io
*Subject:* Re: [HP-Agilent-Keysight-equipment] HP200CD
oscillator

ALL Sprague "Black Cat", "Black Beauty" and? color striped
"Bumble Bee" condensers should be considered bad on sight.
Unfortunately, they are common in older equipment of all makes
and models. The 630V. polyester condensers are a fine
replacement. The only condensers that are polarized are
electrolytics, poyester condensers are not polarized.

??? Bruce Gentry, KA2IVY

On 11/4/21 8:51, Richard Merifield wrote:

??? My unit has Black Cat 0.5MFD 400v axial capacitors for C8
??? and C9. Would 630v polyester unpolarised caps be ok
??? replacements?

Added Option 001 to my otherwise working 5342A.? S/N 1840A01105 which has no line voltage select provisions on the rear panel.? The 10MHz Dale TCXO assembly was replaced with a 10811-60111 OCXO.

After replacement the counter did not power up properly. It alternately flashed a red and green LED on the power supply PCBs with the INT/EXT 10 MHz switch in the INT position.? With this switch in the EXT position The display came up with garbage for digits.

The Red/Green flash mode was consistently invoked and at about a 1Hz rate leading me to believe this behavior was under intentional control.? While reading (Skimming) through the Service Manual the paragraph on Power Supply Adjustments caught my attention. ?The last step of adjusting the over current limit was of particular interest.

The replacement 10811-60111 no doubt consumed more power than the DALE TCXO and thought to try the three Power Supply Adjustment steps outlined in the manual.

I have no extender PCBs but was able to set the switcher frequency and reference voltage without them using clip leads.? The A19R5 current limit adjustment does need the extenders for access.?? With no alternative but to remove the PCB, tweek the pot, then try it, my first CW tweek did nothing.? A CCW tweek did the trick and the counter is powering up as it should and working well again.

I let the OCXO temperature stabilize overnight and set its frequency to within a few 1/10ths of a Hz using a 53310A.

I also got my 8664A working with a surprising fix and will outline my findings later.? Thanks to those here who helped.

Mike

开云体育

Thanks for this very good explanation. In addition to the points you made, I have read the oil fill was often complete, and hydrostatic force would test the integrety of the plastic. Shrinkage and loss of resilience of the case would increase the chance of cracks and leaks. The late 1940s is a fascinating time in history for me. There was a great deal of technological progress made, often with over confidence in new materials? and techniques inspired by? wartime successes that performed very well in the short term but lacked long term reliability. The "Bumble Bee" condensers were excellent in one regard- they had very little residual charge in the dielectric after being fully discharged. When used as a coupling condenser, that can make a difference.

??? Bruce Gentry, KA2IVY

Sprague "Bumble Bee" and "Black Beauty" condensers were molded
improperly, and they will crack, especially the oil filled ones, and
let in moisture. That seems to react with the oil and make it
conductive as well as corrosive. Once this happens, leakage gets very
bad, especially when the condenser is heated by surrounding
components. Many efforts have been made to bake? and otherwise
restore them, but once the problem begins it can not be reversed. The
dielectric charicteristic? is perported to be superb for audio
circuits, and AudioPhools will freak out if these condensers are
replaced, that is until the power transformer, rectifer, output
tubes, and filter choke in their amplifiers are all incinerated. Not
only did Hammarlund use them in receivers, Collins and National did
as well. Tektronix used them in their equipment, and too many
consumer electronics companies to recall all of them.

?? Bruce Gentry, KA2IVY

On 11/4/21 13:45, Richard Knoppow wrote:

Who made those? Some early advertising for Sprague Black Beauty
caps said they were plasticized paper. The main problem with these
is some sort of production problem they had. I have dissected a
number of "bumble bee" caps, these are actually Sprague Black
Beauty caps with striped value markigns. I found the windings were
distorted. I suspect this happened during the encapsulation but
don't know. Some of these caps, the higher voltage ones, were oil
impregnated. The oil was introduced through a tube which formed one
of the leads. It is common for all the oil to have leaked out due
to a lack of sealing at the solder joint between the tube and the
lead. That may have been due to excessive heat when the caps were
installed. The most notorious of the BB caps are those in the
Hammarlund SP-600, however, they were very widely used including in
a lot of -hp- gear. However, in the receiver it is common to find
cracked or split caps or even caps where part of the casing has
come off. I have not seen that in any other make of equipment.
Perhaps just a bad lot or perhaps some difference in installation.
Nonetheless, ALL paper caps become degraded with age. The usual
symptom is an increase in series resistance. Leakage, which is
another term for parallel resistance, is sometimes a problem but
not as often. I don't think any of these caps, even the real oil
filled transmitting caps, was intended to have a lifetime of over
about ten years. The life problem was known and described in some
engineering texts. It was dependent partly on voltage; the closer
the voltage to the rated voltage the shorter the life of the cap.
Likely it was some sort of electrolytic degradation of the paper.
In any case, paper caps should be replaced with modern plastic film
caps. These for the most part will last forever and generally will
improve performance perhaps beyond the original. There is a good
amount of information on the web about the relative merits of
various kinds of plastic dielectrics. Polypropylene seems to be
about the best especially for RF use.

On 11/4/2021 9:33 AM, Dave Wise wrote:

Even the later plasticized-paper “Prokar” and “DiFilm” versions
can cause trouble in some applications – they may not be leaky,
but their Dielectric Absorption and Dissipation Factor are
“through the roof”.

Dave Wise

*From:*HP-Agilent-Keysight-equipment@groups.io
[mailto:HP-Agilent-Keysight-equipment@groups.io] *On Behalf Of
*greenboxmaven via groups.io
*Sent:* Thursday, November 04, 2021 6:25 AM
*To:* HP-Agilent-Keysight-equipment@groups.io
*Subject:* Re: [HP-Agilent-Keysight-equipment] HP200CD oscillator

ALL Sprague "Black Cat", "Black Beauty" and? color striped "Bumble
Bee" condensers should be considered bad on sight. Unfortunately,
they are common in older equipment of all makes and models. The
630V. polyester condensers are a fine replacement. The only
condensers that are polarized are electrolytics, poyester
condensers are not polarized.

??? Bruce Gentry, KA2IVY

On 11/4/21 8:51, Richard Merifield wrote:

??? My unit has Black Cat 0.5MFD 400v axial capacitors for C8
??? and C9. Would 630v polyester unpolarised caps be ok
??? replacements?

ALL Sprague "Black Cat", "Black Beauty" and? color striped "Bumble
Bee" condensers should be considered bad on sight. Unfortunately,
they are common in older equipment of all makes and models. The 630V.
polyester condensers are a fine replacement. The only condensers that
are polarized are electrolytics, poyester condensers are not
polarized.

??? Bruce Gentry, KA2IVY

On 11/4/21 8:51, Richard Merifield wrote:

My unit has Black Cat 0.5MFD 400v axial capacitors for C8 and C9.
Would 630v polyester unpolarised caps be ok replacements?

开云体育

If V1 & V# are out of balance, V3 & V4 will be also.