No, not a toroid. It's a ceramic coil form, overall dimensions 6.5" long,
3.5" in diameter.
Wayne, N1WR
--------------------------------------------------
From: "Jeff Blaine" <keepwalking188@yahoo.com>
Sent: Thursday, January 19, 2012 10:19 PM
To: "Wayne Rogers" <n1wr@chesapeake.net>; <amps@contesting.com>
Subject: Re: [Amps] Pi Network Coil Design
> Wayne,
>
> You are not using a toroid, right?
>
> 73/jeff/ac0c
> www.ac0c.com
> alpha-charlie-zero-charlie
>
> -----Original Message-----
> From: Wayne Rogers
> Sent: Thursday, January 19, 2012 9:30 AM
> To: amps@contesting.com
> Subject: [Amps] Pi Network Coil Design
>
> I'm working on the design of the Pi network for a 4-1000A linear (160, 80,
> 40 and 20 M only), plate resistance is 5500 ohms,
>
> The inductance for 160M is 39.2 uH. I'm planning on using a ceramic
> former 3.5" by 6.5" (31 T #10 Thermaleze spaced over 6").
>
> That part is easy. I have a couple questions about taping the coil for
> the higher bands. For 80M the inductance required is 19.6 uH, half the
> 160M value. So I assume that if I tap the coil at the 50% point I'll have
> 19.6 uH. Do I need to give any consideration for the end effect of the
> shorted out portion of the coil? Whatever the answer I assume it will
> apply for the higher bands (40 and 20).
>
> Thanks guys and 73, Wayne N1WR
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