[Amps] old commercial amp

[Ron Youvan]

Bill L. wa4lav Fuqua wrote:

>     I remember seeing an article in QST where someone took an old AM transmitter using 833As and put it on 80 meters.
> What I did not understand is that they did not make any change to the neutralization coil between the plate and  grid circuits.
> It did not have neutralization capacitors. How did they get away with that? That neutralization inductor should resonate with the grid plate capacitance
> at the operating frequency.

   It may relate to the fact that once neutralized with 180 out of phase 
Voltage the capacitance need not vary (for any frequency) as long as the 
input or output tank remains balanced as is used for push pull 
operation.  The tubes capacitance doesn't change with frequency, the 
amount of miller effect feed back does and amount of degenerative 
feedback does and matches it.  Self canceling.
   Or they could have not neutralized the stage and got lucky.
-- 
    Ron  KA4INM -   Every HAM should have at least one desk MIC,
                    it's the perfect place to hang the cans when
                    CW is "arm chair copy."