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Filament Bias Resistor
Filament Bias Resistor
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Old 15th April 2016, 04:30 PM   #1
sfox7076 is offline sfox7076  United States
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Default Filament Bias Resistor

Does anyone have an opinion on whether it would matter if the resistor used for filament bias needs to be non-inductive. This design uses a 6 ohm resistor at 35W or so. I could do 3 Mills 12 Watt, 18 ohm in parallel or a Dale 50W 6 ohm silicone covered wire wound. Any thoughts on that?
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Old 15th April 2016, 04:35 PM   #2
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
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It needs to be the correct value to get the voltage right. Inductive, non inductive, carbon composition, metal oxide. makes no difference. when induction is concerned unless there is no decoupling capacitor and it is for RF amplification, because the induction it too low to make a difference.
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Old 15th April 2016, 09:42 PM   #3
Enzo is offline Enzo  United States
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And it is for the heaters, not the audio signal path. My heaters don't worry too much about frequency response.
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Old 15th April 2016, 10:04 PM   #4
sfox7076 is offline sfox7076  United States
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That was my logic, but wanted to make sure. I have some Dale wire wound 50 watt resistors and wanted to make sure that I could use them even though they were "inductive". I am running DC on the filaments and thought it would make no difference.
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Old 22nd April 2016, 06:19 AM   #5
Ludwig Haus is offline Ludwig Haus  Australia
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Quote:
Originally Posted by Enzo View Post
And it is for the heaters, not the audio signal path. My heaters don't worry too much about frequency response.
actually its for the filament which is the cathode in a DHT, so it is 100% in the signal path
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Old 22nd April 2016, 06:48 AM   #6
Enzo is offline Enzo  United States
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Ah, then you are privy to details of his project that I am not. I have no idea what circuit he is building. I had assumed for discussion he was planning for the very common DC elevation of heaters for hum abatement.
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Old 22nd April 2016, 03:36 PM   #7
sfox7076 is offline sfox7076  United States
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Right. Filament Bias is for a DHT and is connected directly to the cathode. I am going to start with vitreous enamel wirewound resistors. They are inductive, but I can always change to non-inductive if it matters.

Last edited by sfox7076; 22nd April 2016 at 03:53 PM.
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