12000 series bias question

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rock213
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12000 series bias question

Post by rock213 » Fri Mar 31, 2017 11:23 am

Hi, going to bias my 12000 series, I believe I read to bias to 35 in full power mode, could anyone recommend the bias setting in variac setting thanks?

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neikeel
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Re: 12000 series bias question

Post by neikeel » Fri Mar 31, 2017 3:50 pm

Generally bias around plate voltage rather than absolute figures

Stock 12 series output plate voltage is 490v

so 70% x 25w is 17.5watts

17.5/490 is between 35 and 36ma per tube

What do you measure plate voltage to be at you chosen variac setting (I guess 90v?)

work on that.
Neil

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