A CW amplifier can be designed to run class-C but to be keyed in such a
way as to pass through the linear portion of the amplifying device's
curve when a CW element is starting or ending, in order to preserve the
shaping.
A simple example is the tube-type amplifier that has just enough fixed
bias applied to allow a small amount of plate current to flow (class
AB), with a grid resistor that provides the rest of the bias as a result
of rectified grid current as the drive ramps up. At full power the tube
is running class C with bias way beyond cutoff.
Good 1950's technology that can be made a little more sophisticated and
applied today!
73,
Vic, 4X6GP/K2VCO
Rehovot, Israel
http://www.qsl.net/k2vco/
On 27 Jul 2015 07:32, Alan wrote:
> CW would be another mode that would not need a linear amp I think.
No, CW requires a linear amplifier. CW is not constant-amplitude - the
amplitude changes every time you open or close the key. A class-C
amplifier would mess up the key shaping, causing key clicks.
Any true FSK or MSK signal should not be bothered by a non-linear
amplifier. The only caveat I can think of is that the amplitude of an
AFSK signal may have some ripple on it to the extent that the passband
of the transmit crystal filter is not flat. But I doubt that's a
significant issue.
Alan N1AL
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]
