[Amps] Alpha 374A

[Carl]

How would you fit three 800's in place of a pair of 8874's?

Plus the PS isnt rated for even two 800's running anywhere close to at 
full ratings.

The answer to a voltage doubler is yes along with a regulator. Ive done 
that before with good results.

Carl
KM1H



----- Original Message ----- 
From: "Steve Katz" <stevek at jmr.com>
To: "Robert Perdue" <kc0hfl at cox.net>; <Amps at contesting.com>
Sent: Monday, August 11, 2008 2:48 PM
Subject: Re: [Amps] Alpha 374A


> If you're using three tubes, that would require 4.5 Amps at 13.5V for 
> the 3CX800A7s -- an awful lot of current for a voltage doubler.  That 
> would require one hell of a doubler (huge capacitors), and if you 
> could get it to work you'd end up with about 17Vdc, not 13.5V so you'd 
> have to reduce it or regulate it somehow.
>
> OTOH, if you wired the heaters in series, a single 40V, 1.5A 
> transformer would work.  RFP has (had?) one in their catalog that's 
> very small and only $11.95, P/N F-271U.  Maybe they still have that...
>
> -WB2WIK/6
>
> -----Original Message-----
> From: amps-bounces at contesting.com 
> [mailto:amps-bounces at contesting.com]On
> Behalf Of Robert Perdue
> Sent: Monday, August 11, 2008 11:44 AM
> To: Amps at contesting.com
> Subject: [Amps] Alpha 374A
>
>
> Metal work is all done on the 3cx800 conversion now I am on to the 
> filament voltage and need some thoughts. Not much room for an on board 
> 12v transformer so I was thinking about using a voltage doubler using 
> existing 6.3V winding on original transformer. Any thoughts on the 
> best route to take.
>
> 73,Bob
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