Tube DIY Asylum

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RE: Filament bias

Posted by Thomas Mayer on August 6, 2017 at 04:54:42:
Hi!
The 'old' data sheets are accurate. The curves usually refer to the midpoint of the filament and are taken with AC filament. If you apply DC filament voltage and raise it with a filament bias resistor to 5V, your actual bias is more like - 8.75V.

Anyways there are tolerances between tubes so not every tube sample will bias down to the same exact mA value at the same op point

BR

Thomas