[Amps] Pi-L Check

[wc6w@juno.com]

>In the 23rd addition (and others) of the Bill Orr Handbook "Radio >Handbook," on page 14-22 there is a chart (Figure 44) that shows >cathode circuit values for 
>grounded-grid amplifiers. Range is from 20 to 250 ohms. Perhaps someone >can put this on his web site for those of you that don't have access to >the book.
>
>(((73)))
>Phil, K5PC

Hi Phil,
  If you check the math on that table, I believe that you will discover that the C1 & C2 values from 75 ohms through 200 ohms are interchanged. 

  It "looks" correct as printed because the larger cap is shown on the lower impedance side but, at the low Q (=2), the transformation ratio is such that the Pi network is on the verge of degenerating into an L network.  

  C1 & C2 are so similar that unless you tried using the 150 or 200 ohm values you probably wouldn't notice the error in the real world.

  The 250 ohm entry with Q=3 is correct.

73 & Good evening,
  Marv WC6W



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