On Sep 26, 3:51 pm, james wrote:
For either circuits, bad A and B, to work properly, the D1 diode
current should be ten times the peak instantaineous base current of
the RF power transistor. This type of biasing is good for low power RF
devices. When dealing with large power devices, ie in the 100W and
more class, this is not a good bias as the wasted heat in VR1 and D1
is very inefficient and prone to failure. Also there is no protection
should a voltage spike on the DC supply propogate through. Most
bipolar RF device do not like more than about 4 VDC base/emmiter
voltage. Both circuits have no provisions for limiting the bias
voltage in such a manner to cause permanent damage to the base/emitter
junction.


OK... I don't agree with most of what you've said here... but thanks
for your explanation.