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Old 16th September 2014, 11:38 AM   #1
donovas is offline donovas  South Korea
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Default separate filament transformer for 5u4g?


i use 5u4g for preamp. but hard to get right transformer in korea. so i use
2x 220v secondary transformer for 220-0-220. 1x 5v transformer for filament. this ok? or burn the house?
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Old 16th September 2014, 11:51 AM   #2
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If it is for a preamp and depending on what tubes you use why dont you consider using a 6BY5GA television damper diode for a rectifier?

6BY5GA will deliver 175 mA and the heaters only use 1.6A current @ 6.3V with less voltage drop than a 5U4.

They are also cheap!
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Nigel: "...These go to 11."
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Old 16th September 2014, 12:29 PM   #3
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Absolutely no problem using a separate transformer for the heaters.

As rectifiers regularly use directly coupled cathodes you are actually doing yourself a favour by reducing the interwinding voltage in a single transformer.
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Old 16th September 2014, 01:26 PM   #4
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I find that using one of those 6.3v small filament XMFs & knock down the primary side with a power resistor of 5 to 12 ohms works great for use w/a 5v rectifier.
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Old 16th September 2014, 03:39 PM   #5
donovas is offline donovas  South Korea
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thank you. 6by5ga good choice. but i have 5u4g already

so for plate, two 220-0, 200-0 wired for 220-0(220 and 0)-220 no problem?

Last edited by donovas; 16th September 2014 at 03:42 PM.
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