Posted by Tnuctipun [ 205.188.116.69 ] on June 04, 2005 at 21:37:50:
In Reply to: 45 power trans/6072A driver tube posted by manualblock on June 04, 2005 at 13:18:11:
Hey-Hey!!!,
Anectdotal evidence only. Stuff like, can't do PP Ultra-Linear because the g2 will overheat. then I hear of many folks rigging it as triode in SE w/o troubles.
I don't see any troubles, the g2 is rated for 20 watts, and that's 30 mA at 666 Volts. ~700 looks like a good OP with an 8-10k a-a load. Figure g2 current at between a fifth and a sixth of the anode current and we're O-Tay....
Run anode voltage too low and the g1 bias will be small in comparison to the filament, and that can contribute to hum if you're not careful.
It is a cool looking valve, and pretty tough in the ratings. Say 600V for U-L rigging with 30% g2 and E-Linear tapping and run 100 mA of idle through the anode and I suspect you'r get a really nice 30 Watts.
I am building with its little brother the 4E27. 65 Watt plate and a 5V/7.5A filament instead of the 813's 10V/5A. Both thoriated W filaments, the '27 is a true 3-grid pentode, and the 813 is a beam-Type. Who knows which will sound better. I am sure either can be harnessed.
regards,
Douglas
Praise the Lord, and pass the 813's!
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