[Top] [All Lists]

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

To: <>
Subject: Fw: [AMPS] 470uF/450v caps for $2.25
From: (
Date: Tue, 9 Feb 1999 10:19:18 -0500

On Mon, 8 Feb 1999 13:47:07 -0800 "Will K6NDV" <>
>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 
>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
>    them.
>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 
>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 
>supply warranty probs. Carl just doesn't like anything but Mallory or
>Centralab "computer grade" caps.

I wish people would not try and put words in my mouth.

BTW, Centralab as mentioned above should be CDE and the 381 series I like
to mention are Industrial grade.
I am not against any cap manufacturer and have used more than most over
the years.

I only stress using the proper part for the job since a sudden failure at
HV can be a bit unpleasant.

If those are the same as Commander uses why dont they buy them? Ive sold
surplus parts to Pat in the past and he is not against a bargain.

Why did the few I have here overheat in a doubler supply  ( 4 per leg and
2700V total no load) ? I do not have a Nichicon reference; what is the
ripple current rating and what is the ESR?  Do they compare to the CDE
381 or similar Panasonic?

73  Carl  KM1H 
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at
or call Juno at (800) 654-JUNO [654-5866]

FAQ on WWW:     
Administrative requests:

<Prev in Thread] Current Thread [Next in Thread>