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.

On Wed, 26 Sep 2007 16:10:23 -0700, Telstar Electronics
wrote in
. com:

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.


Your vocabulary also needs help, Brian. Here, let me rephrase what you
said but with the correct verbage:


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


There..... that makes more sense.

On Wed, 26 Sep 2007 16:10:23 -0700, Telstar Electronics
wrote:

|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.
|-------------

Brian

Believe what you want, but there are basic principles of electronics
that you can not deny. Also try and read spec sheets. They don't put
maximum base emmitter voltage in them for the pure heck of it.

james

wrote:
They don't put
maximum base emmitter voltage in them for the pure heck of it.

james

That's what us CBers do first, right James?