>Subject: [AMPS] HV Power Supply Capacitors
>Sent: 3/30/1997 2:44 PM
>Received: 3/30/1997 2:56 PM
>From: John Lockhart, jlockj@minn.net
>To: amps@contesting.com
>
>
>I purchased some small (approx. 1.5" X 2.0") Rubycon
>electrolytic capacitors to use in a high voltage power
>supply for an amplifier. Now I see that one of the
>amplifier manufacturers says in one of their ads that
>"short, stubby light duty soldered-in high-technology
>capacitors" "can't dissipate the heat generated by high
>current."
>Is this true?
In my view, this is technoblathous hipe, John. The spec that largely
determines the amount of internal dissiption is a capacitor's ESR, which
is closely related to its ripple current rating. More amps means lower
ESR. Some stubby caps have large ripple current ratings--so longer
isn't always stronger. A more common source of heat failure is the use
of c.20 k ohm equalizers. The equalizer resistors should not cook the
caps they are supposedly helping. Matsushita 100k ohm 3w MOF resistors
generate minimal heat seem to equalize just fine and are remarkably
stable with time. However, one of our "experts" says that 100k ohm
equalizers allegedly cause all sorts of problems (yet unnamed), but so
far we have sold 19,000 of them and a problem has not yet been reported.
>How do you determine if an electrolytic.
>capacitor can handle duty in a SSB amplifier power
>supply?
Look at the current rating and the temperature rating. The
longest-lasting electrolytics are rated at 105 degrees C. Matsushita
makes some good ones. In this country, they are sold under the name
Panasonic. They are available at Digi-Key. To get a decent price, you
need to buy at least ten, John.
Rich
R. L. Measures,ag6k,805-386-3734
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