[Amps] wide band amplifier ??

[Dan Sawyer]

This is a follow up after an additional experiment. I disconnected the 
source RF circuit (C board) from the driver amp and replaced it with a 
50 Ohm signal generator. The driver amp output was clean across the 
band, however there was feedback into the source on 15 and 20 meters.

How can the output impedance of the RF source board and in the input 
impedance of the driver amp board be estimated from the circuit?

Thanks - Dan

Dan Sawyer wrote:

>All,
>
>This question is regards to a 3 to 30 MHz 'driver amp' in an SB104. If I 
>disconnect the input from the driver amp and examine it, the input is 
>clean. However when the input is connected to the driver it appears as 
>though there is feedback from the amp into the input circuit at some 
>frequencies. The driver amp itself is a push-pull grounded emitter NPN 
>configuration. 
>
>The driver amp output is not consistent across the band. At the high end 
>and at the low end the amp seems fine. However in the middle the output 
>is clipped. Is this a characteristic of the basic design or is it a 
>symptom of something else?
>
>Thanks - Dan
>
>
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