[Amps] power supply for larger solid-state amps

Scott Townley nx7u at arrl.net
Fri Jan 27 19:53:40 EST 2006


I would like to use my SGC-500 in the shack from time to time so my 
attention has turned to a suitable power supply.
This amp runs on 13.8VDC and about 70-80A.
On the commercial side I suppose I could run a pair of Astron 50 or better 
in parallel but that would set me back >$500.
Or I could get a deep-cycle battery and float it with a 35A supply but 
that's $200 (this may well be the optimum solution though).
As it happens I have a 10VAC, 100A transformer (actually it's 
dual-secondary, and each secondary is marked 10V/100A) and a 1F (or 
1,000,000uF) capacitor that the audio nuts use in their cars.  So I'm 
thinking I can build it myself...capacitor input filter would be 14.1VDC 
max which is fine for the amp.
One question is:  what to use for rectifiers?  It seems that only Schottky 
devices are suitable, since they have the lowest forward voltage 
drop.  With a full-wave bridge that's two diode drops right there, I might 
be lucky to get 12VDC out of the whole bit.  I can find a few stud-mount 
Schottky devices for not too much money ($20 or so for a whole bridge 
worth), but they will require a bit of heat sinking.
Any suggestions before I press on?  Is 10VAC just too close to the fuzzy 
edge for a 13.8V amplifier?  1F should be enough filter capacitance, is 
there some reason those audio stiffening caps aren't suited for filter 
service?  (They don't quote any peak or surge current ratings)
TIA,

Scott Townley NX7U
Gilbert, AZ  DM43di
http://members.cox.net/nx7u 




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