Re: [Amps] Line Sections As Plate Lines

[jeff millar <wa1hco@adelphia.net>]

The plate lines are not 1/4 or 1/2 wave long because the resonance and 
matching has to include the effects of the tuning capacitor and output 
coupling capacitor.  This effect shows up well on a smith chart.  The 
end of the line has to look inductive to resonate with the output caps.  
The amount of inductance depends on both length and impedance of the line.

I've been playing with software from Lance Lascari

    (http://tools.rfdude.com/RFdude_Smith_Chart_Program/RFdude_smith_chart_program.html)


and building some matching network at 144 and 432 using the models and 
get good results.  If you're interested, I can send you some examples.

I'm copying my self at work because that's where I run Lance's 
software.  At home, I use a  similar program for  Linux.

jeff, wa1hco

JMLTINC@aol.com wrote:

> Hi QRO gurus -
>
> Let's talk 1/2wl plate lines. 
>
> If you check out PA3CSG's website @ www.qsl.net/pa3csg , or PA7TA's site @ http://www.pa7ta.com/144MHz_RF-Deck.htm , the plate lines on their 2 meter, GS35B amps are about 20.8" (53cm) long.
>
> Everything I have read regarding 1/2wl plate lines says to figure the length for a shortened 1/4wl line (the inductor), and then add a full 1/4wl to that. At 144Mhz that makes a total length of about 28" or so.
>
> I cannot believe their shortened 1/4wl line (inductor) is only 3 tenths of an inch long. Obviously, I am missing something here. Please help!
>
> Thanks in advance-
> John, N9RF
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