[Amps] Fwd: Pi-L In-circuit Adjustment Question

[Bill Fuqua]

At 11:11 AM 2/23/2005 -0500, you wrote:

     Ok that is fine. For reasonable values of Q the "1" is on the order of 
variables you have no control over such as tolerances, parasitic 
reactances, variations in tubes etc. That is why I simplify things to 
Ri/Ro=Q^2.  Ri being the High-Z. end of the L network. Maybe it would be 
better to say Rhi/Rlow=Q^2. For a Q of 10 the difference is 1 percent. Not 
something to worry about in terms of SWR (1.01:1.00).  I have used a Q of 
10 because the output network not only is used to match impedance but to 
reduce harmonics.
For a single PI network you will probably want a Q of 20. So the "+1" even 
becomes less significant.
     For those that have tried the amplifier resonance test, the apparent 
shift in resonance most likely due to the change of input impedance shift 
of the input of the amplifier as you change the tune capacitance. You may 
notice a change in the grid current or exciter to amplifier SWR as you 
change plate tuning capacitor.

73
Bill wa4lav

>
>Hi Rich,
>Before getting into this discussion too deeply, are we all in agreement  that
>the fundamental parallel to series equivalent and series to parallel
>equivalent mathematics are correct and accepted by everyone?
>
>Specifically:
>
>Rs=Rp divided by (Q^2+1)
>
>Rp=Rs multiplied by (Q^2+1)
>
>Q in a parallel circuit= R divided by X
>
>Q in a series circuit=X divided by R
>
>Xp=Rp divided by Q
>
>Xs=Rs times Q
>
>Rs=series resistance
>Rp=parallel resistance
>Xs=series reactance, + for inductive, - for capacitive
>Xp=parallel reactance, + for inductive, - for capacitive
>
>Stopping at this point for now. Any disagreement so far?
>
>73,
>Gerald/K5GW
>
>
>
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