class d amp in 73 ham radio magazine 1964

[DF96]

Originally Posted by KatieandDad

Class D used to only use the peaks of the output waveform, useful for SSB Radio Amplification, useless for audio.

No. SSB needs a linear amp, so usually Class B. I have never heard Class D used for anything other than the switch-mode amplifier used for audio and modulators.

Class D could be used for SSB as part of an EER system, but that uses a different principle so the Class D amp still operates in the normal way we understand today.

Class D should not be regarded as the next one after Class C. Instead, it should be seen as the first of the switch-mode amps: classes D, E and F. E and F are only used for narrow-band applications such as RF or fixed-frequency energy conversion.

[jackinnj]

Jim kyle wrote the "VHF Antenna Handbook" -- i still have a copy around here as i worked 6m and higher when i had my technician class

[phase_accurate]

The oldest circuit of a class-d amp that I have seen so far was from WW2. It was using tubes and it was inteneded to be used as 400 hz inverter (i.e. driven by a 400 Hz oscillator rather than an audio source). Can't remember the carrier frequency though.

Regards

Charles

[KatieandDad]

I'm not a radio man so I stand corrected.

[Ian Finch]

Originally Posted by unclejed613

......the article was by K5JKX. he mentions articles in Wireless World by D. R. Birt and K. C. Johnson, and a jun 63 Audio magazine article by George F. Cooper.
edit: maybe somebody else will have better luck, i have come up with zippo searching for the above authors or articles..

Maybe D.R. Birt was this one? AES E-Library A Motion Transducer for Low-Frequency Loudspeakers

[flg]

I'm thinkin ClassA is biased to work with the full waveform.
ClassB Uses only 1/2 the waveform but as we all know a complimentary style audio amp produces an output of the full waveform. It is effectively biased at zero.
ClassC however is only using some portion of the peak of the signal. Usefull in transmitters but useless for audio.
But, what do I know, I'm a dog