[AMPS] Neutralizing HB amp

[Steve Thompson]

-----Original Message-----
From: Bill Coleman <n2bc@stny.rr.com>
To: amps@contesting.com <amps@contesting.com>
Date: 24 June 1999 03:28
Subject: [AMPS] Neutralizing HB amp


>
>Working on a homebrew  4-1000 amp.  The CN is a piston type
(outer sleeve
>feeds below chassis to the grid circuit, inner / adjustable
sleeve connected
>to the anodes).  Due to space considerations, CN is sitting
appx. 4.5" from
>the anodes (centerline to centerline) or appx. 3" from the
anodes to the
>outer (grid) sleeve.
>
>I can't get a null... as I reduce CN, feedthru steadily
decreases until the
>adjustable cylinder is at the limit of it's travel at
minimum C. I suspect I
>simply have too much coupling from the anodes to the outer
(grid) sleeve
>because of the physical placement of CN midway between the
bottles.
>
>I'm thinking about taking CN apart and shortening the outer
sleeve.  It's
>abt 3" long, thought I'd start lopping off 1/4" at a time,
hopefully to find
>the point where the physical coupling of the outer sleeve
to the anodes is
>less than needed to neutralize, then add capacitance with
the adjustable
>sleeve.
>
>Does this make sense??   Wisdom please.... I recently gave
away my spare CN,
>so this will be a one-way trip!
>
>Thanks all, Bill N2BC


You might try a grounded sleeve (water pipe?) over the cap.
to shield some of it from the anodes and reduce pickup that
way without carving up the capacitor.

Steve


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