[AMPS] Pi-L networks
km1h@juno.com
km1h@juno.com
Fri, 13 Nov 1998 19:53:03 -0500
On Fri, 13 Nov 1998 12:47:23 -0000 Peter Chadwick
<Peter_Chadwick@mitel.com> writes:
>
>Does anyone have any comments about the Q of the L network section in
>Pi-L
>networks? I have seen it suggested that the impedance at the middle of
>the
>pi-L should be the geometric mean of the input and output impedances:
>the Q
>of the L will then be given by
>
>Q = sq.rt.(Ri - Rl)/Rl
>
>where Ri is the intermediate impedance in the Pi-L (i.e. the geometric
>mean)
>and Rl is the load impedance (usually 50 ohms)
>
>For an 1800ohm plate load, this gives a Q of 5 for the L section,
>which
>appears to be the right order of magnitude.
>
>Of course, the Pi section would run at the usual Q - 10 to 15, or so.
>
>Comments, please?
>
>73
>
>Peter G3RZP
Peter,
I thought the same until I started to actually use that concept
Peter....wound up with higher than expected voltage at the Load
capacitor....read "arcs".
By formula that should not have occured leading me to believe that there
is more to it than static design on a piece of paper.
I now "design" for a Q of 2 to 3 in the L and have had no further bad
experiences. The spectrum analyzer confirms the L is performing as
expected.
73 Carl KM1H
>
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