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In Reply to: RE: 211 Push pull grid bias posted by Chip647 on May 01, 2017 at 06:14:51
Some data show the 211 anode rated for 100W. I run mine at 80mA @ 1,050V, roughly -50V at the grid. No color shows in the anodes at this dissipation.
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Buy Chinese. Bury freedom.
Edits: 05/01/17Follow Ups:
thanks Guys.
what i have here is a pair of japanese DIY amp that i check out for a friend . he insit that it came with 211 tubes but when i check the bias voltages and it show around -130v on each tube with the grid R of 33k and the amp checked out ok , I draw the circuit and all seem fine except no output signals. the amp using a Tango FW100-8R ( 8K) .
i thinking this amp must designed to use the 845 tubes not 211 . does this make sense ?
will post the circuit if needed .
Unless the circuit is very unusual and the cathodes are negative, that wouldn't be a 211 amplifier. -130V is in the ballpark for grounded-cathode 845.
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Buy Chinese. Bury freedom.
that is what I think too . the circuit is nothing's special . the output tubes cathode grounded . at the moment with the 211 tubes plug in. i don't think they draw any current with the current negative bias of 130v and hence there is no output signal . evident is that before and after that 33k grid R there is no drop in bias Voltages .
am i correct on this ?
Yes, -130V should completely cut off the tube. Below is the chart. With 1KV on the anode, the tube reaches cutoff at about -80V to -85V. You should have no grid current and no anode or cathode current.
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Buy Chinese. Bury freedom.
Edits: 05/01/17
thanks.
that confirm why i have no output signal when everything's else working as they should.
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