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Re: [Amps] Discrepencies in Pi-net calculators

To: <amps@contesting.com>
Subject: Re: [Amps] Discrepencies in Pi-net calculators
From: "Han Higasa" <higasa@plum.ocn.ne.jp>
Date: Thu, 21 Nov 2013 07:08:05 +0900
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Hi Steve

I am using fomula:

Xc1 = Zi/Q
Xc2 = Zo x  rt(Zi/Zo / (Q^2 + 1 - Zi/Zo))
XL = (QZi + (ZiZo/Xc2))/(Q^2+1)

and with Zi = 50, Zo = 135, f = 28.03 and Q = 2.7
one can obtain

C1 = 306.6 pF
C2 = 194.5 pF
L = 250.9 nH

VK1OD online calculator must be using this scheme.

de Han JE1BMJ

----- Original Message ----- From: "Steve Flood" <kk7uv@bresnan.net>
To: <amps@contesting.com>
Sent: Wednesday, November 20, 2013 11:24 AM
Subject: [Amps] Discrepencies in Pi-net calculators


I've been working through some Pi-network design for an input tuning network
recently and have tried out several online calculators as well as
traditional formulas and  common software.  Using the same input variables
for each tool, I generated three very different results.



For Rin = 50 ohms, Rout = 135 ohms, f=28.03 MHz, Q=2.7



Group 1:  Tonne's PI-EL software, ARRL Handbook formulas, and Jim Hawkins
online Java Radio Calculator.

Cin = 93pF, L=457nH, Cout=79pF



Group 2:  VK1OD online calculator, electronicdesign.com calculator, and
raltron.com calculator.

Cin = 307pF, L=251nH, Cout=194pF



Group 3:  EEweb.com calculator, VK2ZAY online calculator, and Impedance
Matching Network Designer online calculator (sandiego.edu).

Cin=163pF, L=383nH, Cout=113pF



So then, you can see my dilemma here. Why are these so different? And why
the common groupings?



Steve, KK7UV

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