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12V-100AMP Supply for $20.00!!

unit_399

EL CAPO
Jun 17, 2008
2,087
2,888
273
ALEJANDRIA, COLOMBIA SA
Many CB and Amateur operators (Moleculo, for one) are replacing their hi-amperage linear power supplies with switching supplies because of their light weight , relatively small size. and lower cost per amp.

Mainframe computers have utilized high amp switching supplies for several years, and many of these supplies are now showing up on the surplus market. Last week, I purchased an HP mainframe supply from a surplus outlet in Medellin. This particular supply is rated at 12V-74Amps (110vac input) or 12V-106Amps (220vac input). The supply was "reconditioned": i.e. - cleaned, and run at maximum output (94 amp draw) for 12 hours. It measures 6"W x 4"H x 8"D, and weighs about 4 lbs. The cost was 49000 pesos (approx $22USD). Like PC supplies, this unit is "hot-pluggable", meaning it won't turn on unless it's connected to the mainframe. When I mentioned that I was going to use it to power some of my radio equipment, the store's tech showed me how to hot-wire it by connecting 3 pins on the plug together. He also showed me how to adjust the output voltage, and set it to 13.4vdc, which is the max the supply will do.

I tried it out today, and it easily powered my 5-pill TX600 to 800W peak with negligible (.15V) voltage drop.

The plan now is to build a housing with a voltmeter, ammeter, external voltage adjust control, and some high amp connectors. I also need to change the cooling fan to something quieter. I'll post some pics of the finished unit in a few weeks. 73s.

- 399

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Ok, me likee! I want one of these! Where can I get one? Heck, I'd buy 3-4 of them! If I could find something in the 120 amp area, that'd be ideal. I'd put on in my X-Force amp I run. The current supply is about 80A and it's gets stressed at times on SSB.



~Cheers~
 
I often look at these but wonser about hash (static levels) produced in the recieve after hookingf these up. I know amaritron, MFJ and other companies have filtered thes and Im thinking one of those big capacitors for mobile or car audio setups would possibly filter some of this out.

Im thinking with these other companies taking time to figure out filtering and spending a few dollars extra to filter their supplies to eliminate the hash noise other supply companies computer and radio companies alike will follow suite.
 
That was gonna be my next idea rf chokes. I remember someone telling me that those big capacitors would possibly filter some of that out. I didnt understand that theory but figured oneday Ide try it since I have one of those big digital readout caps here.

I am wondering with those capacitors what the best thing for hookup would even be because I would think that the cap would be charged at shutdown and wouldnt that power backfeed into the power supply or whatever else is in line? How would a person set this up safley to bl;eed it off?
 
I often look at these but wonser about hash (static levels) produced in the recieve after hookingf these up. I know amaritron, MFJ and other companies have filtered thes and Im thinking one of those big capacitors for mobile or car audio setups would possibly filter some of this out.

Im thinking with these other companies taking time to figure out filtering and spending a few dollars extra to filter their supplies to eliminate the hash noise other supply companies computer and radio companies alike will follow suite.

I checked out the supply from 26.065 to 28.305 with the antenna disconnected, and didn't hear any hash noise from the supply. I have no way to test any of the other amateur bands. Connected the antenna ... same result-

To be certain that an external cap discharges after shutdown, just put a bleeder resistor across it.

- 399
 
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