Did the
Nauen alternator really sound that clean, i wonder?
Hue,
I took my cue from SAQ the Alexanderson alternator station still
operating in Sweden. Recent recording HERE.
This is accomplished by keying the alternator field coil. I
assume Nauen did something similar.
The Poulen-arc transmitters, on the other hand, could not be keyed
on and off. There was a relay that pulled the tuned circuit off
frequency in the key-up state, resulting in an FSK signal as in
the demo. The trick there is to zero-beat the key-up freq.