H-713
Senior Member
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- Jan 24, 2021
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The cheapest tubes in my SET amp are the 845 radio transmission tubes. They should obviously cost the most, but since they're radio transmission tubes...
I have been eyeing the Russian GM70 tubes for some real SET hifi.
I'm not aware of the 845 ever seeing very much use in radio transmitters- they were mostly used in really big audio amps from that era. If I remember right (and it's been a while since I studied the 845 datasheet), the 845 is extremely low mu and has internal capacitances that make it somewhat useless for transmitting. I know the 211 did see a reasonable amount of amateur service early on- my tube history is a little rusty, but I want to say this would have been the 1920s or 1930s.
Also, any competent engineer should know that you *never* want to depend on tube or transistor parameters for RIAA equalization. With tube gear, it will vary as tubes are inevitably replaced (though tube replacement is generally not a frequent thing), and with transistors it makes the device a royal PITA to manufacture.