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[AMPS] Tetrode Maths? Grid Terminations

To: <amps@contesting.com>
Subject: [AMPS] Tetrode Maths? Grid Terminations
From: 2@vc.net (2)
Date: Wed, 6 Jun 2001 22:12:38 -0700
>
>
>I am building a single 4cx400 amp, i am just about finnished with this 
>project but need some help on the grid termination.
>
>Reading Measures web page it seems that 12.5, 50, 200, and 450 ohms seem 
>to be the practical choices. Assuming I require about 30 volts drive on 
>the grid, i was trying to calculate the drive power.
>
>Using square root P X R  ,,i calculate that it is 20 watts into a 50 ohm 
>load, or 5 watts into a 200 ohm load or 2 watts into a 450 ohm load. This 
>does not include the voltage doubling or tripling effect of the matching 
>toroid transformer. In the case of the 200 ohm load and the voltage 
>doubling transformer i would only require 1.2 watts(square root P X R X 
>200 ohms X 2 for a voltage doubler)  In the case of the 450 ohm load that 
>would equate to 500 milliwatts using a voltage tripler.
>
> What i would like to know if this is the correct way to calculate roughly 
>the required drive power based on the required grid volts. I am using a 
>QRP 5 watt transceiver otherwise i would just use 50 ohms and be happy.
>
>Thanks
>Byron

/\  For peak volts calculations, I use peak watts, not RMS watts.  For 
instance, 5w RMS = 10w-peak.

cheers, Byron
>
.

-  R. L. Measures, 805.386.3734, www.vcnet.com/measures.  
end


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