Monday, March 18, 2013

CHEAP POWER SUPPLY

The other day I acquired a OKLA 500-ATX 500 watt computer power supply.  I did a little research  as I was wanting to build or modify this for Ham Radio.  What I found is that it is possible and relatively in expensive to modify this model.
i began to rummage through my electronics tool box for a 10 watt thermal resistor, a on /off switch, 2 330 ohm resistors. Then I went to radio shack for the binding posts,a chassis mount fuse holder, and 2 LED's.

Now to make this unit produce power it needs to see a need.  That's where the thermal resistor comes in.  I connected 5VDC to it and other end to ground. next I found the supply power lead (sp) on my unit its the grey wire. and located the power good (pgs) lead , on mine its the purple wire.  I connected each wire to a LED. the other end of the LED 's through a 330 ohm resistor to ground.  Then found the wire labeled on/off on the circuit board, on mine its the green wire and connected it to a on/off switch, and to ground.

Next I mounted my chassis fuse holder, and binding posts, then simply soldered the 12VDC wires (on my unit its the yellow wires) through the fuse holder and to the binding posts I wanted to use for 12VDC. then I connected the 5VDC (on my unit its the red)wires to a binding post. Then connected the black ground wires to the black or ground binding posts.

that's it!!  I secured the necessary wiring, sandbar resistor, and eliminated unnecessary wiring. put it back together and tested it. first verifying the supplied voltage and then powered a IC-208H V/UHF radio on the air at 5, 10, 25, and 50 watts.  reports were a flawless clean signal!