[Amps] filament supply d.c. or a.c.

[d.cutter at ntlworld.com]

Working on an army battery set back in the '70's I wondered if polarity would make a difference; I thought that one end would be more biassed than the other wrt grid, but when I reversed the polarity, it made no difference.  Not sure if this is the same effect of which you speak.

David
G3UNA


> 
> From: "Roy" <royanjoy at ncn.net>
> Date: 2008/02/13 Wed PM 04:55:57 GMT
> To: <amps at contesting.com>
> Subject: Re: [Amps] filament supply d.c. or a.c.
> 
> Asked,
> 
> "Looking for reliable information regarding filament supply to amplifier
> tubes. What are the pros and cons for  D.C or  A.C volts."
> 
> 
> Definition of 'filament' indicates a directly-heated cathode. In this case, 
> using DC causes a variable voltage gradient across the length of the 
> filament, acting as a variation in bias at an infinite number of points 
> along its length. This has a number of ill effects. With indirectly heated 
> cathodes, AC or DC is just fine.
> 
> 73,   Roy    K6XK
> 
> 
> 
> 
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