Hacks.

[sureshot]

Not posted for a while, but had to share this as its positive and simple and i've had one running for about 3 months.

Ok i was given a couple of xbox 360 psu's and as a non gamer thought about the 12 volt hack for radio use. As some are aware its an smp psu so the risk of noise was on my mind, but my 175 watt unit is stable and quiet.

Although i have not tested output ripple it must be low i would imagine. There is no transmision noise in use on radios or amps with in its max current rating.

The unit i'm using has 14 amps on the 12 volts output, although not 13.80 volts it powers gear just fine. Most know high current psu's are expensive, and this is such an easy hack i though i would share the positive results, if your electrical savy give it a go your be impressed with it.

On a final it is a mains voltage unit on the primary so if your not sure get help or don't attempt it. Always play safe with electricity. But very easy to do and super stable high current supply.

[Lumiya]

Having no interference when transmitting near the PSU is totally different from connecting it electrically to the PSU. From experience PC style supplies tend to shut down with the connected rf at high power though for cb use might be fine.

[kr0ne]

From experience PC style supplies tend to shut down with the connected rf at high power though for cb use might be fine.

If you spend more than £6 on the PSU this won't be an issue...

I know Sureshot has made a few PSUs from PC power supplies and I (along with many others) use server supplies with no issues whatsoever.

[DX-Digger]

A very good idea, the only thing that concerns me is Protection! No not a featherlite!
Over Voltage and Current!
Mind you if you are capable of modifying such power supplies then I am sure you could add a protection circuit!
Last thing you want is the psu failing big style and taking out your expensive radio's connected to it.
Protection is better than the alternative.
Cheers Mark

[Lumiya]

As long as you don't get rf in the PSU you will be fine, but with no filtering and the simple fact that you're using a common earth if rf does come back down the co-ax it will cause issues. Mind you I was using vhf @ 80w though HF didn't trip it till about 150w. These were decent supplies from a proliant when I used to be Compaq certified many years ago before I retired from IT.

[theham]

depending on the switching ic used on the xbox 360 psu it may already have over-voltage and s/c protection

for those who like to have a dabble with electronics this is a good read on converting old pc power supplies for radio/bench use

http://www.qsl.net/vk4ba/projects/ps.pdf

remember though, most of the switch mode power supplies will rectify mains voltage without a transformer, so there will be 300VDC+ across the large caps, watch your fingers

if you do have any old pc power supplies to hand, remove the yellow/white toroids out of them, they will make decent DC chokes

[cjay]

Another good PSU in a pretty, desktop friendly case is the one used for the USFF Dell Optiplex SX270 and 280, the ones used for USFF 745 are good too.

12V 18A and as low as a tenner delivered.

[cjay]

depending on the switching ic used on the xbox 360 psu it may already have over-voltage and s/c protection

Having repaired SMPSUs for a living, I've yet to meet one from any piece of equipment that didn't have overvoltage or overcurrent protection. Some are crappily designed and go bang if you don't load them but they're rare now, most are stable with no load or will shut down if you don't load them up.

[kr0ne]

As long as you don't get rf in the PSU you will be fine, but with no filtering and the simple fact that you're using a common earth if rf does come back down the co-ax it will cause issues. Mind you I was using vhf @ 80w though HF didn't trip it till about 150w. These were decent supplies from a proliant when I used to be Compaq certified many years ago before I retired from IT.

If you have high levels of RF spewing out of the DC power connectors of your radio, or making it's way back down the co-ax, through the case of the radio and into your PSU via bonding to your home's protective earth then there is something very wrong with your station and I would wager that far more than your radio PSU is being adversely affected...

Why is it that so many people head for the hills as soon as you mention the words SMPSU?

[Lumiya]

So you think that all the rf power magically vanishes from your antenna like those who believe in the mythical 1:1 with absolutely no returning rf???

With no rf filtering even a few watts can overwhelm the switching regulator hence radio switch modes have the filtering as standard.

I wasn't suggesting that you can't use one as a radio PSU but there are limits to using one and every situation can be different depending on power/freq/antenna/..etc

[kr0ne]

I quote:

Having no interference when transmitting near the PSU is totally different from connecting it electrically to the PSU. From experience PC style supplies tend to shut down with the connected rf at high power though for cb use might be fine.

[Lumiya]

Yep which I did say High power might be a problem. I'm all for homebrew and have made my own fair share of PSUs though these days I don't have the test gear I used to have, but I was just pointing out that a PC/console PSU is not an rf protected device so there may be consequences.

Now excuse me as I'm due back up a ladder with my torch as I have a stubborn cobweb that is being a pain in the ar$e to tune and this girl will not be beaten

[theham]

If you have high levels of RF spewing out of the DC power connectors of your radio, or making it's way back down the co-ax, through the case of the radio and into your PSU via bonding to your home's protective earth then there is something very wrong with your station and I would wager that far more than your radio PSU is being adversely affected...

Why is it that so many people head for the hills as soon as you mention the words SMPSU?

there are many stations out there that have problems with RF in the shack, to have it 'cured' by having an earth. except it isnt cured, you've just given it somewhere to go. either feed your balanced antenna with balanced feeder or make sure you have a good RF choke at the feedpoint of the antenna. then youll need NO rf earth in the shack. it all goes to pot with end-fed antennas though, but they should be wiped from the face of the earth as the devils spawn

SMPSU's can be noisy buggers, but there are some very easy methods to cure the noise. put the PSU in a earthed metal box, ferrites or salvaged yellow/white toroids on the DC leads and all will be as quiet as a mouse

[kr0ne]

Yep, or simply spend more than £6 to begin with and purchase a q-u-a-l-i-t-y product...

[ClydeBuilt]

From experience PC style supplies tend to shut down with the connected rf at high power though for cb use might be fine.

If you spend more than £6 on the PSU this won't be an issue...

I know Sureshot has made a few PSUs from PC power supplies and I (along with many others) use server supplies with no issues whatsoever.

Who is 'SureShot' ?
Not from Ireland by any chance is he?