Computer PSU for Radio PSU

[KD9KSO]

I was wanting to get an external power supply for my new Kenwood that is arriving soon, but I wasn't paying $150 for a Kenwood unit. In fact I didn't have to pay for one at all. I have several obsolete towers here and pulled a PSU from a P4 Dell that has long been retired.

The 12VDC rail provides 16A which is about ten times what I need for my handheld on high power.

I clipped all of the connectors off, eliminated the 5VDC and 3.3VDC rail wiring, then bundled the ground wires and the 12VDC wires together and soldered them together. I installed a mounting tab for the backs of the banana jacks and mounted them on a plastic plate screwed to the cabinet to isolate the current from the case. I also used the grey wire to drive an LED indicator that is lit when output voltages are correct. The green wire gets attached to chassis ground to keep the PSU from shutting off when not connected to a MB in the computer.

Works great and didn't cost a nickel to make.

 

[jhooten]

Take 5 volt rail to some USB connectors next time to let you power a bunch of usb devices at once.

 

[KD9KSO]

Don't need it. I have three Lenovo laptops going with 12 ports available.

 

[majoco]

How much RF noise does the inverter in the power supply make - that will be the next question....

 

[KD9KSO]

I don't have a scope to find out and the radio isn't here yet. I have a disc cap across the 12V inputs so I hope that will take care of it.

If I had another barrel connector I could find out using a mobile scanner but no luck.

Those banana jacks are now insulated with heat shrink too.

 

[needairtime]

Currently I'm using one of those little open frame 40W 12V SMPS for powering my radios. I bumped it up to 13.8V for the heck of it.

I'm using it on my VHF/UHF car radios and they seem to sound okay, I can't really discern any additional noise compared to my linear bench PSU or a battery. (Note that alternator/brush and ignition noise is something that these radios need to deal with, so maybe SMPS isn't that bad.)

Only trouble with the 40W PSU is that when it comes time to transmitting, this isn't enough; I may have to end up using a regular computer PSU as well eventually.