bob alexander wrote:
>
>? The problem here is that the Q contribution of C2 is ignored. The
>exact method takes into account the Q contribution of C2.
>
>The "exact" method isn't.
> C2 is not part of the input Z matching section of the pi net
>
>? This is 102 pF if you use the Q contribution of C2.
>
>Input q is no longer 10...it is lower
>
>? So, do the experiment yourself and see what you get.
>
>You get a pi network that is more broadbanded than desired, and has less
>harmonic attenuation than that needed for good design.
Bob, you may be referring to the "old" ARRL method, which has all the
faults you describe.
This was superseded by a much more exact method, which after some years
appeared in the 1995 Handbook and all editions since then.
The new method is the one we're talking about here. It uses the concept
of "input Q" and "output Q", but these are not the same as the overall
network Q. When you analyse the complete network, the overall network Q
is correct.
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.demon.co.uk/g3sek
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