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Re: [Amps] filament transformers

To: Paul Decker <>,
Subject: Re: [Amps] filament transformers
From: Alek Petkovic <>
Date: Sat, 16 May 2009 07:08:26 +0800
List-post: <">>
Go for a larger one as the "off the shelf" 
transformers most likely are NOT rated for 
continuous duty at the nominal 3A or 4A. In other 
words, they'll probably cook when put into service as a filament transformer.

73, Alek

At 04:40 AM 16/05/2009, Paul Decker wrote:
>Hello builders, My amp continues to grow. 
>Â  I'm trying to pick out a filament 
>transformer, such and easy task.    The amp 
>is based on a 3cx800a7 which requires 13.5V +- 
>0.6V at 1.5A.    I was thinking that a 14V 
>transformer would work great.   Ideally, I 
>would like to build the amp with the option to 
>eventually be expanded to a pair of 3cx800's 
>rather than the single.   This would mean I 
>need 3.0A On digikey , they have a 14V 3.0A 
>transformer http ://search. digikey 
>.com/scripts/ DkSearch / dksus . dll 
>?Detail&name=237-1279-ND and a 14V 4.0A 
>transformer http ://search. digikey 
>.com/scripts/ DkSearch / dksus . dll 
>?Detail&name=237-1094-ND So my questions are:Â 
>Â  Â Is it acceptable to use the higher current 
>rating in the single tube version of the amp? 
>  Would current inrush be an issue?   Is the 
>3A version enough, should I get the 4A version 
>or something even larger?  Or, is there 
>something else I should be thinking about using? 
>thanks, Paul, kg7hf 
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