On Mon, 8 Feb 1999 13:47:07 -0800 "Will K6NDV" <firstname.lastname@example.org>
>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.
>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
>bought 100 more when the ad started running. They are the same ones
>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
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
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