[Amps] Pi Network Coil Design

[Jeff Blaine]

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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