The switch-mode power supply design has replaced the ferro-resonant transformer
(Class-A) product used in the telecomms world. A rectifier putting out 100 amps
at negative forty-eight volts weighed-in, let's say ten years ago, at roughly
300 pounds.
A 100 amp switching module weighed thirty pounds five years ago, and the ones
we are installing nowadays weigh twenty pounds apiece.
The solid-state devices need less heat-sink mass and there are fewer demandds
for iron-core transformers and chokes. The newest modules are called ARGUS and
they weigh about 23 pounds and put out a clean 100 amperes, DC at +24 or -48
volts.
However, the PA design for high power as discussed herein sounds redolent of
the 5-tube AM receivers of forty years ago where one side of the a.c. line was
directly connected to the chassis and the power plugs weren't polarized like
they are today. I wouldn't want to be on a DXpedition using a switch mode amp
with one side of the chassis possibly hot, in a tent, in the rain, etc., etc.!
Hal Mandel
KA1XO
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