Be careful when extrapolating from limited experience.
Clipping is one source of distortion, but not the only possibility.
The definition of clipping is simple: it occurs when an amplifier
output voltage would be higher than the input voltage. The
signal waveform is "clipped" so that the output voltage is no
greater than the input.
Most audio amps are Class A or AB and won't clip except under
extreme conditions. But radio frequency (RF) amps have
many different designs. Class A ("linear amplifiers") have
relatively low efficiency but as with audio amps generally don't
clip unless excessively overdriven.
Not so with Class B and C. By definition these amps have
clipping all the time, but they are used for modes (CW or
"Morse Code," frequency-shift keying, etc.) where it is not
critical to have a pure waveform. The gains in throughput
power are considered worth the tradeoff.
Class B designs are basically lab-only curiosities, but Class C
used to be fairly widespread in ham radio before the advent
of the "linear amplifier" boom in the 1960s. (Actually most
ham amps are Class AB2 cathode-driven a/k/a "grounded
grid" where clipping can occur if the amp is improperly tuned).
The whole trick with Class C operation was to maximize output
while keeping the clipping from causing undue distortion and
interference. In my CW op days I used a couple Class C amps
(known fondly as "boat anchors" because of the size of
the old gear). Here's one I used a few times, the Viking Courier,
which could operate in Class A for voice or Class C for CW:
http://www.qsl.net/la5ki/org/vi/cou.htm
The advent of a new generation of tubes like the 3-500Z in the
1960s and the decline in CW-only stations led to the practical
demise of Class C, although it is now undergoing a boom
in a completely different context for digital transmission modes.
fh
-----------------
>On 12/5/06, Stoddard, Kamal <[EMAIL PROTECTED]> wrote:
>> The difference is with the waveform. Compression/distortion is not
>> (...really) the same as clipping. And generally speaking, they're
>> recognized as being the result of a lack of analogue or digital overhead
>> respectively. You can call it what you want, and in extreme cases of
>> compression, you can get that square wave form (clips), but it'll never
>> sound the same and that's the real reason for the distinction.
>
>exactly, ive never heard any analogue signal "clip" in anything like
>the way of just overdriving the signal into your computer will. by the
>time your analogue signal got that high, it would probably just sound
>like white noise anyway.
>
>tmo
>
