I am using a 10/vt25 as the input/driver tube for another 10/vt25. From the RCA 10 data sheet average plate characteristics indicate that -5 volt bias and 150 volts plate the current consumption should be 10 ma. So I use a large 4 ohm resistor in series with the filament. Filament current is 1.25 amps, so my bias voltage s/b (4 0hms)(1.25 amps)=5v.
I have a B+ of 380 volts and I need a voltage drop of 230 volts @10 ma so I use 23Kohm resistor. R=230volts/.01 amps = 23kohms.
When I hook everything up I get 176 volts on the plate and current is 8.9 ma. Obviously not 150 volts, 10 ma @-5v. Any thoughts on why such a discrepancy between actual results and those predicted from the plate curves? TIA for any responses I'm really at a loss over this one.
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Topic - Filament bias - vetmedrobert@gmail.com 13:01:05 08/05/17 (23)
- Anode resistor value - andy evans 02:41:30 08/06/17 (1)
- RE: Anode resistor value - vetmedrobert@gmail.com 09:15:30 08/06/17 (0)
- 10Y Filament bias circuit - andy evans 02:23:46 08/06/17 (9)
- RE: 10Y Filament bias circuit - vetmedrobert@gmail.com 08:09:18 08/06/17 (8)
- Heaters in series? - andy evans 08:15:04 08/06/17 (7)
- RE: Heaters in series? - vetmedrobert@gmail.com 09:04:24 08/06/17 (6)
- RE: Heaters in series? - Caucasian Blackplate 10:13:59 08/06/17 (5)
- RE: Heaters in series? - vetmedrobert@gmail.com 10:27:13 08/06/17 (4)
- RE: Heaters in series? - Caucasian Blackplate 11:07:57 08/06/17 (3)
- RE: Heaters in series? - vetmedrobert@gmail.com 11:51:39 08/06/17 (2)
- RE: Heaters in series? - Caucasian Blackplate 19:22:32 08/06/17 (1)
- RE: Heaters in series? - vetmedrobert@gmail.com 20:41:36 08/06/17 (0)
- RE: Filament bias - vetmedrobert@gmail.com 16:53:55 08/05/17 (7)
- RE: Filament bias - Thomas Mayer 04:54:42 08/06/17 (6)
- RE: Filament bias - vetmedrobert@gmail.com 07:10:01 08/06/17 (5)
- RE: Filament bias - Caucasian Blackplate 09:38:39 08/06/17 (4)
- RE: Filament bias - vetmedrobert@gmail.com 09:55:30 08/06/17 (3)
- RE: Filament bias - Caucasian Blackplate 10:04:34 08/06/17 (2)
- RE: Filament bias - vetmedrobert@gmail.com 16:12:15 08/06/17 (1)
- RE: Filament bias - Thomas Mayer 23:55:26 08/06/17 (0)
- RE: Filament bias - Tre' 14:35:08 08/05/17 (2)
- RE: Filament bias - vetmedrobert@gmail.com 16:46:46 08/05/17 (1)
- Oops - Tre' 17:08:11 08/05/17 (0)