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[AMPS] More L-net/Series to Parallel questions

 To: [AMPS] More L-net/Series to Parallel questions Peter_Chadwick@mitel.com (Peter Chadwick) Wed, 17 Feb 1999 09:02:56 -0000
 ```Jon asks: >OK I GIVE UP!!!! WHY DO THE EQUATIONS NOT JIVE?????? Because the example given isn't resonant. 7.6pF at 28 MHz is -j747.9 ohms. In shunt with 4600 ohms, this gives a series equivalent of -j728.6 in series with 118.5 ohms. 1 microhenry is j 175.9, so the impedance looking back is -j552.7 ohms in series with 118.5 ohms. If you have a series inductance of j728.6 ohms (4.141 microhenry), then Q = 728.6/118.5, or 6.15. Similarly, from the parallel case of Rp/Xp, 4600/728.6 = 6.15. I did a bit of playing on the Smith Chart. While adding the inductance in series between the plate and C increases the value of C1, it does push up the circuit Q as a whole, as evidenced by the narrower bandwidth when a frequency sweep is done. That's working back from the SWR looking back into the network when loaded with the correct laod impedance at the plate. 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/ampfaq.html Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com Search: http://www.contesting.com/km9p/search.htm ```
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