"amdx" wrote in message
...
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

I received a reply to my question from the webpage author.

"In the formule Rp=2.pi.f.L.Q , I use the Q of the coil in the right-side
part of circuit diagram 2.
This Q is halve the value of the coil Q in the left-side part of circuit
diagram 2.

I consider the right side part of diagram 2 to be a new unloaded circuit,
with it own unloaded Q.
With unloaded I mean here "not loaded with diode or loudspeaker".

Maybe one might say; it's not unloaded because the antenne is connected"
But as you see in circuit diagram 2, in the right side part, there is no
antenne anymore.
It's just a new LC circuit with it's own Q value, wich we are gonna load
with diode and speaker.

The calculated value of Rp is the value which the diode sees, in the
situation with the antenna connected"