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[AMPS] construction of parasitics

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Subject: [AMPS] construction of parasitics
From: (2)
Date: Tue, 24 Jul 2001 07:00:09 -0700
>Hi Skipp,
>I have a serious question, and I think the answer would be of great 
>use to many people.
/\  Quite possibly not to those who read AMPS without a filter, Mr. 

>> So I did the proper math home work to figure out 
>> the coil inductance values for my suppressors which 
>> were right in line with Rich's paperwork. My math 
>> and testing came up with inductance values about 
>> 85 to 95% of the suppressor kit values.
>Can you share the formula you use in determining the amount of L 
>and R required to stabilize an amplifier?
/\   There is nary a magic answer or esoteric formula. 
-   In "Parasites in Transmitters" (1935) Mr. G.W. Fyler said that adding 
resistance to parasite-resonant circuits is the cure.  Determining how 
much resistance is largely a trial and error process aided by educated 
guesswork and pervasive glitch* protection.     

>I can use a series of measurements to determine the approximate 
>value of R and L in most cases, but I've also found many cases 
>that require testing of several PA's to optimize suppression. A 
>simple formula would certainly save work!
/\   First off, one needs to realize that roughly equal currents need to 
flow in L=supp and R-supp at the anode's VHF resonant freq.  Secondly,  
the electromagnetic fields of R-supp and L-supp need to be perpindicular. 
  Thirdly, adjust L-supp to cause R-supp to dissipate maximal heat at 
-  But alas, I know it is definitely difficult to teach old dogmatists 
new tricks.

* American Heritage Dictionary:
 -  "Probably from Yiddish glitsh, a slip, lapse, from glitshn, to slip, 
from Middle High German glitschen" ...
-  WORD HISTORY: Although in retrospect glitch seems to be a word that 
people would always have found useful, it is first recorded in English in 
1962 in the writing of John Glenn: ³Another term we adopted to describe 
some of our problems was ?glitch.¹² Glenn then gives the technical sense 
of the word the astronauts had adopted: ³Literally, a glitch is a spike 
or change in voltage in an electrical current.² In this very passage we 
see how the word moved from its narrow, technical electronic sense to a 
more general sense, even if the astronauts were not necessarily the first 
to extend the meaning of glitch. Since then the word has passed beyond 
technical use and now covers a wide variety of malfunctions and mishaps.

-  R. L. Measures, 805.386.3734,AG6K,  

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