It's a finely-balanced design. The driver is a 500-Volt tube with 1200 Volts on the plate. By rights it should go poof the first time it's keyed. Had a memorable conversation with an "engineer" at Wawasee Electronics many decades ago. Asked him how they get away with that. He explained that keeping the screen grid at 120 Volts DC or so was what made it possible, along with a zener that biases the driver tube near to cutoff. The big tubes have zero bias, which makes them more sensitive to a low drive carrier. Good thing, since the AM carrier has to be turned way down in the driver to keep it from cherrying up and failing too soon. The 3-500Z tubes tolerate zero bias in part by keeping the anode supply at around 2400 Volts. And by keeping the carrier below 150 Watts or so.
It's a hot-rod design. Things we do to it are meant to minimize seized rings and dropped valves. But push it too hard and you'll wrap it around the tree at Dead Man's Curve.
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It's a hot-rod design. Things we do to it are meant to minimize seized rings and dropped valves. But push it too hard and you'll wrap it around the tree at Dead Man's Curve.
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