[Amps] Pi Network Coil Design

[Wayne Rogers]

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 at yahoo.com>
Sent: Thursday, January 19, 2012 10:19 PM
To: "Wayne Rogers" <n1wr at chesapeake.net>; <amps at 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 at 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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