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ECF801 Triode/Pentode any useful application ?

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There are some Triode/Pentode combinations like ECF801 / 6GJ7 in which the two tube systems share a common cathode.
Are there any known applications where both systems can be used in a circuit ?
audio, power supply or whatever ?
I mean aside from their original purpose as oscillator/mixer in a frequency changer or using just the triode or the pentode separately ...
 
The fact that you can't get the Redford symetric doesn't surprise me.
I don't like that circuit.
To use the ECL801 as a paraphase splitter try it like this.Didn't build it but looks promessing.
Mona
 

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Yes, floating paraphase, I guess.
I like the split cathode resistor, makes it easy to match non-equal tubes.
Modifyed it a little, hooked up the pentode in triode mode. All I had to do is to change the upper cathode R to 220 and the lower R to 470 ohms. Et voilà - symmetric outputs.
Not that I need a phase splitter right now, but good to know ... maybe some day ...
 
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