Identify decoupling capacitors?

[John McMillan]

I'm trying to identify some decoupling capacitors, probably ceramic.
They're orangish red, about 8 x 6 x 1mm axial leaded.
They are labelled on the top, that is the 8 x 1mm curved face
away from the leads:-

104
YME

To the left of this is what I take to be the trade mark which
is a narrow slanted V which is as large as the two lines of
lettering above.
The left arm of the V is about 5 degrees clockwise from vertical
while the right arm is about 10 degrees so the whole V points
down to the left.


I assume 104 means 100nF as it usually does. What does YME
mean?

I'm asking because these caps were provided for a fairly exacting
operation, namely decoupling photomultiplier dynodes in cryogenic
conditions. They'll be run at about 200V and , er, -190C.
They look awfully small for 100nF/300V and I have my suspicions
about their temperature coefficients.

 

[legg]

On Thu, 22 Mar 2007 19:18:55 +0000, John McMillan
<j.e.mcmillan@sheffielddot.acdot.uk> wrote:

I'm trying to identify some decoupling capacitors, probably ceramic.
They're orangish red, about 8 x 6 x 1mm axial leaded.
They are labelled on the top, that is the 8 x 1mm curved face
away from the leads:-

104
YME

To the left of this is what I take to be the trade mark which
is a narrow slanted V which is as large as the two lines of
lettering above.
The left arm of the V is about 5 degrees clockwise from vertical
while the right arm is about 10 degrees so the whole V points
down to the left.


I assume 104 means 100nF as it usually does. What does YME
mean?

I'm asking because these caps were provided for a fairly exacting
operation, namely decoupling photomultiplier dynodes in cryogenic
conditions. They'll be run at about 200V and , er, -190C.
They look awfully small for 100nF/300V and I have my suspicions
about their temperature coefficients.

At 8x6x1mm, they are very unusually shaped for axial lead capacitors..

Vitramon (now Vishay Vitramon) used to make some some very nice
capacitors, both ceramic and porcelain, for higher voltage or more
exacting situations. They were not notably small. Their trademark was
Vy, sloped roughly as you describe.

Vishay offers axial/radial leaded monolithic ceramic parts at 200 and
500V, up to 47nF, in the X7R dielectric class. These will display a
negative voltage coefficient. NPO dielectric parts are going to be
hard to come by above 10nF. You might try Temex Ceramics.

YME doesn't mean anything in the EIA, ANSI or MIL codes.

For this application, you will have to qualify your own parts anyways,
as few are characterized below -55C. This is time consuming and should
be performed on known parts that do what you intend them to do over
their originally-designed range.

RL

 

[John McMillan]

In article <a7u803p06mlo30n2546e4dgij6d3uk7ah7@4ax.com>,
legg <legg@nospam.magma.ca> wrote:

On Thu, 22 Mar 2007 19:18:55 +0000, John McMillan
j.e.mcmillan@sheffielddot.acdot.uk> wrote:

At 8x6x1mm, they are very unusually shaped for axial lead capacitors..

Whoops, I meant radial.

Vitramon (now Vishay Vitramon) used to make some some very nice
capacitors, both ceramic and porcelain, for higher voltage or more
exacting situations. They were not notably small. Their trademark was
Vy, sloped roughly as you describe.

I thought of them but couldn't find an old trademark. All the
stuff on the web has their current trademark. Thanks
for the confirmation.

Vishay offers axial/radial leaded monolithic ceramic parts at 200 and
500V, up to 47nF, in the X7R dielectric class. These will display a
negative voltage coefficient. NPO dielectric parts are going to be
hard to come by above 10nF. You might try Temex Ceramics.

YME doesn't mean anything in the EIA, ANSI or MIL codes.

For this application, you will have to qualify your own parts anyways,
as few are characterized below -55C. This is time consuming and should
be performed on known parts that do what you intend them to do over
their originally-designed range.

I know. I guess its time to do some proper tests.