[Milsurplus] [ARC5] GO-9 Project: Why the Resistor?

[Hubert Miller]

Thank you.
So I surmise this is a greater effect in larger tubes?
Also that this capacitance could vary with variable filament heating, such as filament voltage change?
-Hue

>Hi

The oscillator filament is raised off ground because the filament to cathode capacitance would show up
across C305. C305 is “inside” the oscillator loop. Stray across it will tune the VFO and introduce drift.
Depending on how the tube is made ( manufacturer to manufacturer) this probably varies a bit.

Bob



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