What says the group? Do we saturate in Class C or not?
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In order to get any semblence of efficiency, the drive waveform should drive
the stage from near-cut-off to near-saturation, somewhat like a switch.
However, depending on how hard the sinusoidal input signal drives the "Clacc
C" stage, the conduction-angle and thus the duty-cycle of the output (before
filtering) will increase or decrease, resulting in variable output power in
the load.

Joe
W3JDR


"Tim Shoppa" wrote in message
oups.com...
wrote:
I'm reading David Rutledge's excellent "The Electronics of Radio."

In Chapter 10 -- Power Amplifiers, he discusses Class C amps and says,
"In addition, if we drive the transistor clear to saturation, using the
transistor as a switch, the dissipated power can be greatly reduced,
because the saturation voltage is low. This is Class C
amplification..."

I'd always throught that in Class C, while you'd operate the device so
that it was cutoff during most of the cycle, but not saturated.

Is this just a different definition of Class C?

I checked back with SSDRA and EMRFD, and didn't see anything about
driving Class C amps into saturation?

What says the group? Do we saturate in Class C or not?

Saturation is itself a somewhat mushy point. There's a V_sat specified
on the datasheets but the actual definition of saturated is entirely
application-sensitive. As a practical matter as you add more base
current you will go further into saturation (up until you melt the
base-emitter junction and then all sorts of wacky things ensue).

Choice of drive level and output level and load impedance in a Class C
amplifier certainly will in many cases put the device into saturation.

Tim.