Greetings AMP folks, from Japan !
I have no experiences to use DC to 813 but I am
using DC for 211(GE's VT-4C) with thoriated-tungsten
filament for my home brew stereo amplifier. I applied
the reversed polarity to each 211 (Right/Left channel)
and every half year I swap 211 tubes at Right/Left channels.
The power source of the filament is simply bridge rectified
from the secondary windings of the transformer.
I think inrush current harms the filament if low impedance
power supply is used, such as switching power supply.
'73 de JA2DHC, Kazuo Ohashi
e-Mail: ohashi@ny.airnet.ne.jp
Packet: JA2DHC@JL1ZND.11.JNET1.JPN.AS
Webpage: http://www.ny.airnet.ne.jp/ohashi/
"Randall D. DuCharme" wrote:
> Greetings,
>
> I was toying with the idea of running the filaments DC in an 813
> amplifier I'm starting. I was just told today that if I did that I'd
> have to reverse the polarity on the tubes periodically or suffer
> shortened filament life. Is there any truth to this? Is this something
> unique to the 813, something in common with all thoriated-tungsten
> types, or some sort of strange Halloween prank? I've never heard of
> this.
>
> Many thanks!
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