R: [AMPS] L-Pi net...downside?

[Rich Measures]

>
>Rich says:
>
>	>?  When an L-network is resonant, it is a dead short, Peter. 
>
>Rubbish. Twaddle. WRONG!!! Do the mathematics of series parallel transforms.
>
€  If the reactance of the inductor is equal to the reactance of the 
capacitor, the L-network presents a short to the generator.  What is the 
impedance of a series-resonant circuit?

>> > The Eimac definition of R/XC1 is one.  The other definition of Q is a 
>>> lot more complicated and gives a different result.  I use Eimac Q.  I am 
lazy.  
>
>That's an approximation that applies only to the complete network and falls
>over at low values of Q. It may be one you can get away with - it doesn't
>mean that it's right.
>
€ Are Ian's calculations acceptable to you?.  

>	>> Further, you have not yet given a rigorous definition of
>resonance
>	>>capable of  being modelled mathematically. 
>
>>  equal and opposite reactance - - which does not mysteriously
>>disappear whenever a dipmeter is brought near.    
>
>Only applicable to very simple circuits, and the 'resonant' frequency that
>it gives is not the resonant frequency that we want - which is where the
>correct non reactive load is presented to the PA tube.

€  We have a simple Pi-network.  We will connect correct RL and Rout 
resistances to the ends of the Pi-network.
>
>>?  The advantage of the dipmeter is that it obviates prestidigitations.  
>
>Reinforces misconceptions about technical matters.  

€  Mr. Rauch groused similarly about the intrinsic evils of dipmeters 
when I discovered that a directly grounded grid had a slightly lower 
resonant freq. than when it was instead grounded through a series 
capacitance.  
>
-  cheers, Peter


Rich...

R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  


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