[Amps] Discrepencies in Pi-net calculators

[Larry Benko]

Steve,

Look at the quality of the groups.  The group 3 solution shows up on 
several university web sites including 2 text books I have. Therefore I 
wouldn't just base my decision on the quantity in each group.

Perhaps a much better way to approach the problem is to just forget 
about Q (unless this is just an academic exercise).  It is extremely 
easy in LTSpice (free) to plot the frequency response and input return 
loss for all 3 groups and then make your decision.  Are you concerned 
about impedance match over frequency, harmonic suppression, or something 
else?

73,
Larry, W0QE


On 11/20/2013 4:37 PM, Steve Flood wrote:
>>> Larry wrote:
>>> 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.
>
>   
>
> I used the same variable values for each tool, including a specified Q.  I
> was hoping to generate some discussion in the group as to how the results
> fall into three distinct groupings, rather than asking for help in designing
> a specific network.
>
>   
>
> I've added a few more tools to the groupings:
>
>   
>
> Group 1
>
> Tonne's PI-EL software
>
> ARRL Handbook formulas
>
> Jim Hawkins online Java Radio Calculator
>
> G3SEK spreadsheet
>
> Leonard Anderson's article ""Pi Network Design" in the March, 1978 issue of
> Ham Radio.
>
> (BTW, I found a print error in one of the formulas in that article).
>
>   
>
> Group 2
>
> EIMAC "Care and Feeding..." p. 52-55
>
> VK1OD online calculator (derived from EIMAC)
>
> Bill Orr 23rd Radio Handbook p14-18
>
> electronicdesign.com calculator
>
> raltron.com calculator.
>
>   
>
> Group 3
>
> EEweb.com calculator
>
> VK2ZAY online calculator
>
> Impedance Matching Network Designer online calculator (sandiego.edu).
>
>   
>
>   
>
> Steve, KK7UV
>
>   
>
>   
>
>   
>
>   
>
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