push-pull El34 bias question - Page 2 - diyAudio
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Old 7th June 2012, 12:39 AM   #11
cancon is offline cancon  Canada
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Thanks for that note, fmb, that is good to know. We're talking EL34's, BTW...not sure if that changes your response? Also by 10mA of screen current for both tubes (thus 90mA) I take it thats 5mA per screen?

I changed out the 39K bias resistor for 25K and now I can hit 80mA half-way through the bias pot's swing.
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Old 7th June 2012, 05:10 PM   #12
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Quote:
Originally Posted by cancon View Post
Thanks for that note, fmb, that is good to know. We're talking EL34's, BTW...not sure if that changes your response? Also by 10mA of screen current for both tubes (thus 90mA) I take it thats 5mA per screen?

I changed out the 39K bias resistor for 25K and now I can hit 80mA half-way through the bias pot's swing.

My mistake that was a typo, I did mean to type EL34 not EL84.
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Old 8th September 2012, 04:33 AM   #13
cancon is offline cancon  Canada
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Didn't know if I should start a new thread... here goes. Building a bias tester with 4 tube bases. I was wondering if it safe to use a 125V 0.3A rated rotary switch for selecting between test bases (2 poles, 4 position) for switching both cathode and plate. I'm thinking that even though there is no current draw in this scenario (simply measuring with a DVM), 500VDC will stress the switch...Should I jump up to a 125V@5A rating?
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