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

To: <amps@contesting.com>
Subject: R: [AMPS] L-Pi net...downside?
From: measures@vc.net (Rich Measures)
Date: Wed, 4 Aug 1999 04:39:07 -0700


>
>> >>?  the dip you see with a dipmeter coupled to a Pi-network is not on the
>> >> operating frequency.  
>> >
>> >Now there's a new definition that's not in any of the
>> >textbooks............not a very scientific one either, if I may so, Rich.
>> >
>> ?  Do you believe that a Pi-network is resonant on the working frequency,
>> Peter?
>
>Careful Peter, it's a very special dip meter. It can also measure Q, 
>and the anti-resonant frequency of a control grid just by placing it 
>near the socket leads.

?  I am familar with control grid resonance.  For the 3-500Z, this is 80 
- 90 MHz.  What is  anti-resonant frequency of the control grid, Tom?.  
>
>According to Rich's magic grid dip meter, a pi-network isn't ever 
>resonant. 
>
>Phew!!
>
?   RL = 2000 ohms.  R out equals 50-ohms.  Freq = 7.00MHz.  Q = 10  
Therefore, C1 = 2000 ohms/10 = 200 ohms.  From calculation, C1 = 114pF, 
C2 = 562pF, L = 5.06uH.   Since C1 is effectively in series with C2, 
C-net = 94.8pF.  The resonant freq. of 5.06uH in parallel with 94.8pF is 
7.266MHz.  

-  cheers, Tom


Rich...

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


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