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The big international shortwave broadcasters used to routinely run 250Kw or even 500Kw but at about 85-90% modulation. The would run the modulator tubes for a certain time then swap them out to the RF amplifier section and install new tubes inthe modulation stage. This was for economic reasons BIG tubes are expensive. They wanted the sheer power of the carrier to overcome fading and interference while realizing that 85-90% modulation was more than adequate to reach their audience. Tubes operate much harder in class B audio service than in class C RF service.

[QUOTE="Captain Kilowatt, post: 679093, member: 39"] The big international shortwave broadcasters used to routinely run 250Kw or even 500Kw but at about 85-90% modulation. The would run the modulator tubes for a certain time then swap them out to the RF amplifier section and install new tubes inthe modulation stage. This was for economic reasons BIG tubes are expensive. They wanted the sheer power of the carrier to overcome fading and interference while realizing that 85-90% modulation was more than adequate to reach their audience. Tubes operate much harder in class B audio service than in class C RF service. [/QUOTE]

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