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Author Topic: Computer Power Supplys for Ham Radio  (Read 4419 times)

« on: November 23, 2001, 10:53:32 AM »

Does anyone know about any information on using Computer Power Supplys for Ham Radio?  Bill

Posts: 3

« Reply #1 on: November 23, 2001, 01:41:17 PM »

There are some good things about using a computer power supply for ham radio, but mostly bad.
First, computer power supplies (I'll use CPUPS from now on) ARE highly regulated, have excelent RF rejection, and are readily available. But that doesnt make them good for ham use.
First, the voltages you get are 5vdc and 12vdc. Most newer ones do NOT let you vary the voltages. Even if you have one of the older ones that has a way to vary it, it usually only goes from 11-13vdc. As has been pointed out on this board (I think I read it here) if you operate your radio at 12vdc and transmit for any time you could be pulling too many amps, and end up burning out your radio. NOT worth it. Remember, your car is 13.8vdc, pretty consistently.
Second, most newer CPUPS do NOT have a direct on-off button. Yes, you can probably figure out what the sense pin is, but because of the above it's still not worth it.
Third, even if you ARE willing to use the CPUPS at 12vdc for your radio, you need to get a pretty big one to do a decent sized radio/amplifier. My big PCs 300W CPUPS is rated at 10 amps on the +12v, max. It would cost about $50 new. Being as a 12ampcontinuous, 14 amp peak 13.8vdc regulated Pyramid PS is less than $70, and WILL work right, you're much better off just getting that.
I HAVE read somewhere (again, I think somewhere in the eham baords) that it was suggested that you could get several old CPUPS, and serial connect the 5vdc's to make 15vdc. Trouble with that, the 5vdc's are usually VERY low amp taps. You muight get enough for an HT, but not anything bigger.
I suppose if you really wanted you could get two CPUPS and serialize the 12vdc's to get 24, then get a realy big voltage regulator and crank it down to 13.8, but that's an awful lot of trouble for something that stil may burn up your radio. And you'd be limited by the most restrictive amp rating. The nice 13.8vdc PSs will NOT burn up your radio!
BTW I just went through this over the last two weeks, and ended up buying a pyramid two days ago.
I AM building a remote "head" for the PS, with volt and ammeters, just so I know. I like meters.
Now my question - If you're going to be operating an HT that takes 1.5amps, and an amp that takes 10 amps, should you have one 12 amp PS or a small one for the HT and a large one for the amp? I'm thinking one big one that does both (which is what I chose,) else you could get a voltage differential where you dont want it.
hope this helps!

Posts: 984

« Reply #2 on: November 23, 2001, 01:45:33 PM »

    Computer power supplies usually consist of more than one voltage output and generally of small amperage. For instance: 12VDC3A, 5VDC5A, 5VAC1A. If you are going to use or do use a QRP radio, then the 12VDC portion may work for you. Remember also that some computer power supplies are dirty which is why we hear them when they are near our radios. If you can find a power supply that works, has the current requirement you need and is far enough removed from your radio or is clean, then use it. Good luck.

Posts: 3746

« Reply #3 on: November 23, 2001, 09:49:59 PM »


Here is a link to an article that may be of interest to you.

August has written an article on using older computer power supplies to power ham radio equipment.

73 james

« Reply #4 on: November 24, 2001, 02:25:07 AM »

Thanks James, that was just the type of info. that I was looking for. I have so many of those old Power Supplys lying around, I was wondering about what to do with them. Thanks everybody else for the effort they put into my question. 73's...Bill
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