[Amps] Alpha 374A

[Steve Katz]

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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