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

To: r@somis.org, amps@contesting.com
Subject: Re: [Amps] Fwd: Pi-L In-circuit Adjustment Question
From: TexasRF@aol.com
Date: Sun, 20 Feb 2005 08:51:28 EST
List-post: <mailto:amps@contesting.com>
Hi Rich, here we go with the fly excrement in the pepper again! 
 
.The discussion was about in circuit adjusting a network with an rf  
analyzer/bridge. No mention of L networks, etc. When you connect a resistive  
load of 
the correct value to the input and an rf analyzer to the output of an L  
network or  Pi network , you can adjust for 50 +j0 at the analyzer. As you  
know, 
j0 means no series (or parallel for that matter) reactance is present.  Also as 
you now, that is what we commonly consider "resonant". 
 
Your point about the L and Pi networks not being resonant is mute. We are  
trying to confirm that the network will transform the equivalent plate load  
impedance to the desired output load impedance, 50 ohms in this case. since  
there is more than one solution to doing this and there are obscure 
contributors  
to the network values, there is a risk of screwing up. Hence the need to 
confirm  that the impedance transforming network is working as expected or at 
least 
close  to expected. By observing the values of C1 and C2 we can also 
determine if the  network operating Q is at or near the expected value.
 
Can one expect to set a network in this manner and never touch it again?  
Maybe if the Q was <1 but in the case under discussion, not likely. I would  
wager you a case of your favorite suds though that the PA would fire up  making 
more than 50% of expected power.
 
Resonant or not, I know of no safer, easier or  more accurate way to  cold 
test an output network. Do you?
 
My  Sincere Regards,
Gerald/K5GW
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