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Identify decoupling capacitors?

Discussion in 'Electronic Components' started by John McMillan, Mar 22, 2007.

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  1. 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.
     
  2. legg

    legg Guest

    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
     
  3. Whoops, I meant radial.
    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.

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