[AMRadio] RE: negative cycle loading

[W7QHO at aol.com]

Brett,

Are you using the three diode circuit at   <
http://www.amwindow.org/tech/htm/3diodeka.htm>?
If so, this thing will clip all negative peaks that cross the "keep alive" 
level.   How abruptly would depend on the internal impedance (i.e., stiffness) 
of the keep-alive supply but would give essentially the same effect as clipping 
in the PA by crossing the zero line. This is where your splatter is coming 
from.   Give the circuit at <http://www.amwindow.org/tech/htm/3diode.htm> a try. 
  I've had good results with this setup adjusted to give up to 200% in the 
positive direction without overmodulating the negative side.   For the resistor, 
I've found a value around the load impedance presented by the PA works well. 
You must use a scope to adjust this scheme.

Good luck.

Dennis D. W7QHO
Glendale, CA


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