> From: bkmak@airmail.net (Bob Kmak)
> Subject: Re: [AMPS] Re: Bent filaments
To: <amps@contesting.com>
> Date: Mon, 14 Jul 97 16:38:03 +0000
Hi Bob,
> Tom,
> Are you saying that a string of smaller HV supply capacitors in series
> is better than a big oil-filled cap, for big-bang protection purposes?
Absolutely. The best electrolytics are ones that are just as large as
necessary. Overkill in the power supply transformer and rectifiers is
a good idea, but one the capacitor is large enough to get you way out
on the knee of the voltage curve, adding more C actually can create
headaches.
Oil filled caps have very low equivalent internal series resistance
(or ESR), and so if the amplifier has a momentary fault the source
current can be hundreds of amperes. Electrolytics often have between
1/2 and one ohm per capacitor, so a string of eight gives you a
fraction of the discharge current of a large oil filled cap.
A overkill plate choke is the same way. The smallest wire size
practical for a given current provides the most resistance and surge
protection.
Some components like filament transformers and chokes are better
sized smaller while others like plate transformers are better sized
larger.
> I'm new to this stuff, and just trying to figure it out.
IMHO, the person who quits trying to figure stuff out or doesn't
care to learn HOW things work might as well be a silent key.
73, Tom W8JI
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