On 27 Sep 2006 15:52:43 -0700, "Telstar Electronics"
wrote in
. com:

Frank Gilliland wrote:
Vcc
|
|
|R|
|R|
|R|
|
______|_______
| a |
_|_ _|_
\ / D1 \ / D2
_V_ _V_
| |
| |
__|__ __|__
___ ___
_ _


1. Measure voltage at point (a) with respect to ground.

2. Heat D1 with a soldering iron. Watch voltage drop.

3. Let D1 cool. Watch voltage go back up.

4. Heat D2 with a soldering iron. Watch voltage drop.

5. Let D2 cool. Watch voltage go back up.


Thus endeth electronics lesson for today.

Ok, that's just what I thought you'd draw. I claim this is useless and
won't work right. If you hook point "A" up to the base an RF device...
it'll do exactly what I described before. Either the base-emitter diode
will be on... or the other diode will be on. If the plain diode is
on... you have no current in the base of the transistor. It will be cut
off... and you have no bias at all. If the base-emitter diode is on...
you'll have some bias... but the tracking diode is off and can't do
anything. How in the world will that track anything, in either case.
Answer: It won't.


Well, you just proved your foolishness by:

(1) contradicting the engineers at Motorola and other transistor
manufacturers who use diode biasing in the test circuits for nearly
every bipolar RF power transistor ever made;

(2) proving that you have never actually measured the open-base
voltage of a bipolar RF power transistor (hint: it's less than logic
would dictate);

(3) failing to understand that a bipolar transistor is a CURRENT
amplifier, not a VOLTAGE amplifier;

(4) demonstrating that your internet education didn't include the
basics of semiconductors -- specifically that the Vf/If curve has a
slope greater than zero;

(5) ignoring the fact that those "parallel" diodes which you thought
were "puzzling" were actually in series and used as temperature
sensors for a seperate bias regulator circuit; and

(6) posting your technical ignorance and inexperience in a public
forum where it can be read by any potential buyer of your amp.

So what's next from you, Brain? Some vague, Skippy-esque excuse about
how it's "part of a bigger picture"? Will you pull an Eitner and deny
the facts based on a claim of omniscience? Or will you just go back to
your same old fallacious argument that anyone who has never built a
cheap CB amp doesn't know squat?

The circuit works. If it didn't work for you then either you screwed
it up or didn't understand its function. I'm guessing both.