Bias clamper for class C amplifier

[paulmdrdo]

Good day everyone! I'm reallly having a hard time understanding why the output of the negative clamper used to bias a class C amp is a smooth sine wave.
Because from what I have read the Base-Emitter diode of the transistor is on for the value of the input above 0.7v. If it is on then, shouldn't the output be flat when the input is above 0.7v?

 

[KlausST]

Hi,

It still is an analog part...which causes increasing current, no ON/OFF.
And there is some series resistance...

Klaus

 

[paulmdrdo]

Hi,

It still is an analog part...which causes increasing current, no ON/OFF.
And there is some series resistance...

Klaus

What do you mean by no on/off? I'm still confused. The base-emitter is supposed to be conducting(ON state) when the input signal is near its peak. Otherwise the diode will not turn on.

 

[KlausST]

Hi,

It is not zero_current / zerhm, it is not hard ON/OFF, it is soft somehow. The closer you go the the 0.7V the softer it looks like. If you have a 10V input you will rather recognize it as hard clamp.

It may be considered as OFF at 0.55V.
But then it will slowly become conductive.
Depending on the device you may consider it at 0.7V as ON ...or even at 1V not fully ON.

Klaus