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On 11/15/2010 03:49 PM, amdx wrote:
On the webpage http://www.crystal-radio.eu/engev.htm the author diagrams a crystal radio with Rp as the losses in L1 and C1. Then he goes further and loads L1C1 with an antenna, this reduces Q by 1/2. He then adds we can calculate the value of Rp as follows: Rp=2.pi.f.L.Q (Q Unloaded). My question; Why does he do all further calculations with Rp rather than 1/2Rp, since the Q of L1C1 is reduced to 1/2 by the antenna loading. MikeK From what I read, I guess: 1. He works out the optimum match between antenna and LC tank. 2. She investigates the optimum match between LC tank and load completely unrelated to 1. OTOH, I would be glad to find a reference on how to accurately derive the proposed equivalent circuit of the diode detector at low signal levels. Pere |