>
>For the benefit of readers trying to learn something, read inserted
>snippets below :
>
>
>> >
>> >Rich Measures wrote:
>> >>>>? There is more than one way to figure Q.
>> >>>
>> >>>Evidently - like to tell us your definition?
>> >>>
>> >>? I don't have one. Eimac defines Q as the ratio between RL and the
>> >>reactance of C1. None of the Eimac formulae can be used without choosing
>> >>a value of Q - as defined by their definition
>> >>.
>
>EIMAC defines nothing with those formulas. The formulas are public
>domain. They're parrotted in EIMAC's book, just like they are in all the
>other handbooks. EIMAC has not done anything original with Pi network
>design. EIMAC is not the author of these formulae.
>
>>
>> ? There are nevertheless two ways to define Q.
>> >
>
>WRONG. There is one definition of Q.
? Isn't there a loaded Q and an unloaded Q?
>There is more than one formula for
>calculating Q and it varies with the circuit under consideration. The
>formula for Q printed in the "sacred" EIMAC book, for Pi networks, is
>incorrect. It is also incorrect in any other book that uses the same set
>of formulae. (Note that it is the correct formula for the Q of the C1
>capacitor, but not for the network as a whole)
>
>> >>>The definition I'm using is Q = XL/Rs, where Rs is the transformed
>> >>>effect of all resistive components, when made to appear in a series loop
>> >>>with L.
>> >>>
>> >>? A definition which does not work with Eimac's formulae.
>> >>
>
>Already stated, "EIMAC's" formulae is incorrect. Newcommers should
>ignore all future references to the so-called EIMAC formulae. Refer
>instead to the ARRL handbook, 1995 and later editions only. Earlier ARRL
>editions have the same flaw as EIMAC. The same is true of all the ORR
>Radio Handbooks.
? Agreed. . And how much improvement do the new, improved formulas
afford the user? Ian calculated 5.57 uH. I calculated 5.06uH using the
old, less than perfect formulas. .
>
>> >I still can't believe I'm reading this!
>> >
>> ? You can read it on pages 35, 36, and 37 in *Care and Feeding of Power
>> Grid tubes. Q is used in all three formulas. Q is not calculated. Q is
>> selected by the designer.
>> >
>
>Q is selected by the designer in the corrected formulae too...no
>difference. However, Q is used to calculate the values of C1 AND C2 in
>the corrected formuale...not just C1 as in Rich's EIMAC book.
>
? Agreed.
>Anyone with a copy of EIMAC's Care and Feeding..., should remove pages
>35, 36 and 37, and deposit them on Bandini Mountain (forget where I heard
>that one).
>
? I can't unless I get Alzheimers.
>>
- - However, the real issue here is not the less than perfect accuracy
in the old Eimac formulae.
>
- cheers, Phil
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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