I worked for P. R. Mallory Capacitor Company about 45 years ago and we
made all sorts of capacitors including the extruded aluminum cans,
both AC and DC units. I don't remember any screen material in any of
them. Inside was etched aluminum foil rated at specific voltages.
The foil was split into needed widths, cut to needed length and tabs
attached. This was matched with slightly wider paper and a non-etched
aluminum foil length added to the other side of the paper
insulations. "Rollers" would roll this foil and paper sandwich into a
roll. The raw roll was then immersed in electrolyte solution, ours
was glycol based, akin to car antifreeze, and once saturated, a low
voltage was applied with voltage increasing over time until the units
were "aged". Faulty units were trashed. Good units were canned in
aluminum cans using black tar to hold them in place. Bottoms were
sealed and tabs soldered or spot-welded to terminals. I was part of
Quality control so I got to "blow them up". Maybe this summary is
useful?
Joe Taylor N4NAS, Glasgow, KY
______________________________________________________________
From: Jack Schmidling <[EMAIL PROTECTED]>
Reply-To: Discussion of AM Radio in the Amateur Service
<[email protected]>
To: Discussion of AM Radio in the Amateur Service
<[email protected]>
Subject: Re: [AMRadio] old round aluminum filter Capacitors
Date: Wed, 01 Nov 2006 09:44:00 -0600
>John E. Coleman (ARS WA5BXO) wrote:
>>What was in these things? The inside of the can is lined with a
>>perforated
>>brittle screen perhaps some carbon stuff. The center post is
>>connected to a
>>foil which is wound in a spiral. I don't think it is laminated
>>foil?
>
>Not sure just what you have but electrolytics are/were made by a
>process that produced the dielectric when fired up. The foil was
>uninsulated and immersed in a chemical soup that coated the foil
>with a very thin layer of dielectric when activated. It's
>electro/chemical magic.
>
>js
>
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