Video of Class D/E AM transmitter modulated 200%

Does “shutting the carrier off” cause splatter using a Class D modulator and a Class E PA? See the surprising results…

Pretty obvious I’m no cameraman, but thought you might like to see reception of the AM transmitter, modulated 200% positive, on a run-of-the-mill receiver.

Note the S-meter leaping about to the modulation and the detail on the spectrum scope. No splatter! Audio bandwidth is limited here to about 5k/cs.

Although this TX has the capability of negative peak limiting, I chose to *not* use it for this experiment. FYI.

Thanks to the BBC World Service for the test!

It’s a bit dark, shaky, etc, but you get the idea…

The old-timers rule about not shutting off the carrier — does that apply to AM using a modulation transformer only? Or is this a pecularity of the Class E? Or the fact that its a series modulator?

If you have any thoughts, let me know…

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More stuff on the AM transmitter here