After a short time reforming of modern caps anything over 1ma at 450V I
consider junk.
Ive also rejected new caps that started acting up at around 440V which
caused Ameritron grief when I told them. They found out their supplier was
short changing them on the aluminum and have been testing....and rejecting
since.
I buy large amounts of repair parts from them so they listen when I report a
problem.
Carl
KM1H
----- Original Message -----
From: "Gene May" <gene-may@hotmail.com>
To: "Amplifier Mailing List" <amps@contesting.com>
Sent: Wednesday, March 28, 2012 8:19 PM
Subject: Re: [Amps] How to know when filter caps begin to fail
>
>
> 1. I, too, have shared Bob K6UJ's experience with an electrolytic cap
> exploding, and the mess was awful enough to make me conservative about the
> issue of replacement. The goo between the foil seems to be somewhat
> corrosive, was slow to clean off, and damaged some of the metal it got
> on.
>
> 2. I'm cheap, and have used many surplus electrolytic caps. Along with
> Glen K9STH's suggestions, I suggest that anyone also using surplus caps
> connect them in series and place some DC across for a few hours, then see
> how much they leak. I toss anything that gives off any more than a few
> watts -- I've seen leakages of 20 - 30 mA at voltages of around 300V (6 -
> 9 watts) on surplus caps -- and know others who are even more conservative
> than I about throwing them out. They can be so much cheaper than new that
> I think it is cheap insurance being conservative. Along with Glen, I have
> found that frequent usage tends to make electrolytic caps last longer, not
> go bad faster.
>
> 3. Finally, particularly if you use surplus caps, I suggest that AFTER
> THE CAPS ARE THOROUGHLY DISCHARGED, every so often it is worthwhile to
> simply feel them after they have been under power for a few hours, and
> replace the whole batch if any one of them is particularly warm.
>
> Gene May
> WB8WKU
>
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>
>
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