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Subject: Shorted Turns in RF Tank Circuits
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Date: 03/16/00 at 1:20 PM
Posted by: Mike
Way back in my ham radio days I recall that a common method of switching frequency bands in a high power RF amplifier is to short out unwanted turns of the final amplifier inductor by switching a series of taps. The L/C circuit is often in a "pi" configuration. Once the required turns are shorted out (via a rotary switch), the plate capacitor must then be tuned for minimum plate current and maximum output. Well, I have two questions concerning this... 1. Why don't the shorted turns overheat, and overload the amplifier? 2. Why short out the unwanted turns, instead of simply switching taps on the inductor?Thanks!
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