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Fw: [AMPS] 470uF/450v caps for $2.25

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Subject: Fw: [AMPS] 470uF/450v caps for $2.25
From: (Will K6NDV)
Date: Mon, 8 Feb 1999 13:47:07 -0800
Here a few of the reply I received from my question about meeting the
The last commend is kind of interesting, since it look like the Capacitors
are used in a commercial amplifier.
73 Will

Well, after seeing all the flak I would like to add
a few comments.

1. When you series capacitors that are not all the
    same exact capacitance there is a different voltage
    across each. Those with a spec such as +80%-20% can
    be a problem if you don't series enough to allow for
    this error.  Remember V=Q/C...... If  V is changing quicker
    than the time constant of the resistors across the
    capacitors (ripple frequency, SSB or CW operation, SPARKS etc)
    the voltage across the capacitors may not be the same.
    And if you have too few in series one may break down and then
    cause a cascade of failures until all are lost.
    I plan to use 20 capacitors for a 6KV power supply.
    At this price it and the space I have available it is
    no problem. That also means that  I have a 50% safety
    margin and these are supposed to be 20% tolerance caps.
    Maybe I'll add 4 more just for good luck. That is
    over 10KV worth.
      I have seen many power supplies built such that if
    one capacitor shorts out the power supply voltage then
    is greater than the total ratings of the capacitors left.
    I just see no reason to cut it so close.

2. Don't put them where they may get. Near power resistors,
    plate tank circuit or tube etc.

3. Do check their capacitance and leakage before installing

4. And have plenty of shielding around them just in case one or
    more do go. Electrolytics will go bad some day. You can bet
    on that.

5. I have not used these and if you want you may look up the
    characteristics in a catalog yourself. These are not real
    old like the stuff we find at ham fest or used equipment.

>For what its worth....I've been using those caps for several years and
bought 100 more when the ad started running. They are the same ones used in
the Commander amps, and I know for a fact that Pat doesn't have any power
supply warranty probs. Carl just doesn't like anything but Mallory or
Centralab "computer grade" caps.

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