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[Amps] Filament Choke mod

To: <amps@contesting.com>
Subject: [Amps] Filament Choke mod
From: "Thomas R. Williams" <n2cu@magtrol.com>
Date: Tue, 15 Jun 2004 13:00:44 -0400
List-post: <mailto:amps@contesting.com>
The filament voltage on my Drake L7 is 5.25 V, which conventional wisdom says 
is too high by about 0.3 V. I'd like to avoid placing a series resistor in the 
primary of the filament transformer since the antenna relay gets powered by 
another secondary on the same transformer and I'm building in a relay speed-up 
circuit - I need the extra voltage for that.

The filament choke appears to be wound with 11 AWG formvar wire. I calculated 
the additional resistance needed to drop the voltage and found that rewinding 
the choke with 14 AWG wire would do the trick, as far as resistance goes. If I 
use the same number of turns, should I be concerned about the inductance being 
a different value due to the wire size? Any other things to consider looking at?

73,
Tom N2CU <><




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