K7ITM wrote:
.. See the link I gave above.

Well, admittedly I was taking it a bit out of context, but my posting
was a response to Walter's "Do really believe that there was a
transmitter in the 1920's that could deliver
500 kw?"

I think the operative word here is "deliver", by which I would mean
"radiated into the far field". Dissipating half a megawatt in the
system is impressive, but not necessarily as a transmitter.


And the answer is, yes, I do. Maybe not valve-based, but
more than one transmitter, and capable of modulation as well:
apparently Poulsen arc transmitters were FSK, since they couldn't be
keyed on and off.

One scheme was to change the resonant frequency of the antenna (via taps
on a coil), which was the frequency determining part of the system, the
arc providing a negative resistance characteristic for making an oscillator.

And apparently the alternator based transmitters
could be keyed at up to 100wpm. I'm pretty impressed with what the
radio engineers of that era were able to achieve.

It IS very impressive, but whether they could *radiate* half a megawatt
is sort of a good question.

Consider for comparison the ELF transmitters in Michigan..several
Megawatts to radiate less than 10 Watts

Or Project Sanguine, which was soemthing like 800 MW to radiate a few watts.


I know of several Tesla coils that have average power inputs in the
hundreds of kW range, but they don't radiate a whole lot, even with 20+
meter sparks as an antenna.



Cheers,
Tom