Ladies and Gentlemen,
I frequently contribute technical knowhow to a CB trucker's forum
(before you press delete please read on). The question came up
concerning my assertion the single final transistor amplifier, typical
in CB transmitter output circuits, operates as a Class A amplifier since
the modulation required is AM and sometimes SSB, both being amplitude
style modulations, and both desiring of good linearity in the
amplification (at least I think so).
I know for sure CB output circuits are not push pull since they have
only one power amplifying transistor.
Some are suggesting the less than 180° Class C amplification method is
what CBs use. I understand this requires a good tank circuit to
complete the sine waves, but is supposedly inappropriate for amplitude
style modulations like AM, DSB and SSB. Various resources suggest Class
C is fine for CW and FM.
I am sure by now you are saying "That's interesting John, really, but
what does this have to do with Elecraft?"
Well, I suddenly remembered some advertisement for an HF Ham Transceiver
that offered Class A mode in its output circuit for some improvement in
some parameter. Funny thing is I guess I thought Ham Transceivers
always used either Class A with a single device or, perhaps, Class AB or
B in a push-pull arrangement.
What I need to know from Elecraft and/or any of you is:
- What is the final amplifier class (A, AB, B or C) used in, say, the
KX1, K2 or K3?
- Is it actually possible to use Class C with an amplitude modulation
scheme like AM, DSB and/or SSB?
- Is the final amplifer in the KPA100 Class A?
- Do most Ham Transmitters utilize pairs of power devices in a Class AB
or B in a push-pull arrangement?
Hopefully this will fine tune my EE knowledge of circuits and make sure
I have not missed something I should know so I can continue to represent
the ham community well when offering advice to the other radio groups.
Thanks for your help.
John
KX4O
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