"Dee Flint" ) writes:

Most CW computer programs are set up so that for transmission you set the
radio to CW mode and then run a line from a computer serial port to the
straight key jack on the radio. Therefore you are using an actual A1A
transmission. Right off hand, I don't know any CW programs that feed a tone
into the mic jack although I suppose there could be some out there.

Dee, N8UZE


On the other hand, there was a time when some commercial SSB rigs
did use an injected audio tone to send CW. Whether or not they
actually sent A1 would have been determined by the purity of the tone
oscillator, and the carrier suppression and unwanted sideband suppression
of the sideband rig.

A more common occurance was RTTY, when AFSK was often used to send
FSK on an SSB rig. (I suppose it was more common since it was
easy to unbalance a balanced modulator and just key a stage for
an SSB rig, especially when it came from the factory that way, while
commercial rigs did not tend to have built in FSK ability and of course
frequency shifting often resulted in slight variation of how much shift
occurred depending what you modified and what you shifted. And of course,
it was easier to inject an AFSK generator into the sideband rig than
mess with frequency determining elements in the rig.) Nobody really
thought badly of this practice, so long as it provided a decent
sinewave.

LIkewise, SSTV always (well maybe not in recent years, I don't know)
be done by modulating an audio oscillator, and then feeding it into
the mic input of the SSB rig.

With good supression of the carrier, good suppresion of the unwanted
sideband, and a pure enough audio oscillator, the only thing that
would be noticed about the output signal would be that the dial
of the transmitter doesn't directly show the transmitted frequency,
since of course the carrier isn't being turned on and off, an audio
oscillator is so it provides an offset.

This is precisely why two-tone oscillators are needed for testing
SSB transmitters. Because only then are you actually modulating
the output. Otherwise, it's just a carrier.

Michael VE2BVW