Bottlehead Forum
General Category => General Discussion => Topic started by: Deke609 on August 09, 2020, 02:49:43 PM
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I am just putting together what will hopefully be the last Mouser order for the Kaiju rebuild. And since I'm going "all out" I figure I'll get some nice Vishay 1%, highly temp stable 1K bias resistors for the 300Bs. I've gotten into the habit of automatically choosing non-inductive wirewound resistors - figuring that inductance in a resistor is a nuisance best avoided. But for a cathode bias resistor, where I want a constant current through the resistor to maintain a constant voltage drop, maybe inductive is the way to go?
Any thoughts on that?
cheers and thanks, Derek
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Inductance in a resistor can be a big problem when you have high frequency signal passing through it and the inductance in the resistor makes the resistor appear to be a much higher impedance value at those high frequencies. In a cathode biased 300B amp, the cathode resistor has a huge cap across it, so there's nearly no signal current passing through the resistor, so a little inductance isn't problematic.
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Many thanks PB. That makes sense. I forgot to take into account the role of the cathode resistor bypass cap in maintaining a relatively constant voltage bias. So I think I'll just stick with non-inductive out of an abundance of caution.
cheers and thanks, Derek