Re: Cell phone noise into opamps

Robert Latest wrote:
["Followup-To:" header set to sci.electronics.design.]
Joerg wrote:

I did build audio gear with tubes, back when even Ge transistors were expensive. Pre-amps, compressors, bigger amps, and one really big amp. That one had six color-TV H-tubes in it. You could make the plaster rain down from the ceiling with a few cords on the E-guitar.

Yeah, I used to have a dozen of those PL519's, too, but never got around to doing anything with them. But they were impressive beasts, and ambundant in Sperrmüll TV sets.

I've never seen a hobby electronics magazine pick up on the idea of putting some of those to good use, but maybe I just haven't looked hard enough.


Well, those tricks weren't published much since everyone wanted to be the guy with the meanest amp. Do a twang on the E-guitar too strongly and a 16 amp breaker would pop, and this was on a 230V circuit.

Later we built RF amps with them. Germany had an odd rule that allowed you to use up to 150W total plate dissipation. What counted was the official data***. PL519 were out because they were rated at 35W. But the old PL509 was rated 30W so you were allowed five. My amp delivered a solid and sustained 1.2 kilowatts (!) clean RF output at 3.5MHz. Measured on a calibrated Bird wattmeter. But we had a guy who pushed it a step further: He built a pulse-modulated version (in the 70's!). His could send the 2kW Bird meter needle into the right peg with gusto.

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Regards, Joerg

http://www.analogconsultants.com/
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