[Amps] Discrepencies in Pi-net calculators

[Mike Waters]

To add to the confusication here, here's the pi-calc I use here:

http://www.ifwtech.co.uk/g3sek/pi-l-net.zip

I thought G3SEK's spreadsheet above was pretty good.

I know VK1OD's is also good, but I found it a little confusing until Owen
kindly explained it to me. I forget the details, but I think you have to
use two of his calculators on his site. The first one IIRC involves the
characteristic curves of the tube, and then you take the results of that
and transfer it to another of his calculators on another page.

IIRC, Owen has three RF PA calculators.

73, Mike
www.w0btu.com


---------- Forwarded message ----------
> From: Larry Benko <xxw0qe at comcast.net>
> To: amps at contesting.com
> Date: Tue, 19 Nov 2013 22:31:50 -0700
> Subject: Re: [Amps] Discrepencies in Pi-net calculators
> Steve,
>
> According to my calculations all 3 networks match 50 ohms to 135 ohms @
> 28.03MHz.  However Group 1 has a Q of 1.9, Group 2 has Q of 4.7, and Group
> 3 has Q of 2.7 according to my understanding of nodal Q.
>
> 73,
> Larry, W0QE
>
>
> On 11/19/2013 7:24 PM, Steve Flood wrote:
>
>> 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
>>
>