Server converted power supplys.

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Re: Server converted power supplys.

Postby sureshot » 11 Sep 2016, 02:05

So its time I put together a variable test load for these monster power supplys. I can't or don't need a load of linear amps for testing, and its to expensive.

I thought lamps, but that's ok for a 100 watts testing etc any higher get daft with lamps. As I first attempt I'm going to use 50 watt aluminum clad resistors. I figure if I use 10 x 4.7R 50 watt resistors I will get a shade over 300 watts at 12 Volts, and each resistor will be disapating a little over 30 watts each. Rather than fixed load I was thinking switched divisions of 50 watts using toggle or rocker switches via high current relays to take the increasing load, up to the maximum.

I did think I might take this up to 500 watts for load testing these units, but can't see much call for that higher current rating. Might be wrong on that though. Now just to look out for a donor heatsink that will handle 300 watts maximum load, and using 120mm fans for cooling.
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Re: Server converted power supplys.

Postby sec1223 » 11 Sep 2016, 07:30

Should be a good build
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Re: Server converted power supplys.

Postby sureshot » 11 Sep 2016, 10:46

sec1223 wrote:Should be a good build

Hopefully.. For those units I can get up to 13.8 Volts or close to it, each of the 10 4.7R resistors will be disipating a shade over 40 watts each. But most units voltage will be somewhere in the middle on voltage. Just need a modest scope now to see how clean the outputs are under varying loads.
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Re: Server converted power supplys.

Postby sureshot » 29 Mar 2017, 00:42

Been a while..
A couple of 750 Watt psu's, plan is 24 Volts, floated an HP DPS 1200, picture with the drill box, note the nylon machine screws and stand offs. These replace the steel ones to float the output, this avoiding tripping the other unit. AC ground stays intact. The other pictures are the 750 Watt donors for the 24 Volts series project. Just light testing first, raming it up over time.

Some more progress as it comes.
Had to keep images small, larger ones won't upload.
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Re: Server converted power supplys.

Postby sureshot » 29 Mar 2017, 00:43

You'll have to rotate your phone / tablet / pc etc.
No don't rotate your pc lol. Just how it posted them.
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Re: Server converted power supplys.

Postby sureshot » 03 Apr 2017, 20:22

Still some tests to do under load, but that's a 1200 watt dps and a 750 watt dps hp floated on the output. They maintain the AC ground, in series I've loaded up to 100 watts for a few hours. Its only a light load. Not having put together a resistive test load gadget yet. Final test will be to load it up with 300 watts to see if its stable over time, that's about 25 Amps. The 750 watt units like those in the picture above are a bit more tricky to mount with nylon machine screws. There is not much room to manoeuvre around in there. When i get two wired up in series with a high load I'll post pictures showing voltage and current, a pair running in series.
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Re: Server converted power supplys.

Postby sureshot » 10 Apr 2017, 11:28

Loaded up with 5 x 50 watt halogen lamps, i can only measure up to 20 Amps on the red meter. Image is the best quality i could upload. I tested maximum load of 7 x 50 watt halogen lamps. That's 350 watts, but in real terms it would be less due to losses in cable and lamps. It runs very mild warm. When it does get warmer the fan ramps up, from cold the fan is silent. All good. That's a 460 watt unit in the picture, i would think the 750 and 1200 watt units would run high powered Amplifiers all day long. But that had 7 x 50 watt lamps on it continously for over three hours. Very impressive for its size. The 460 and 750 units only need a single jumper link, same pins as the 1200 watt hp dps.
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Re: Server converted power supplys.

Postby sureshot » 10 Apr 2017, 11:51

To come will be a pair in series loaded up with respective series lamp loads. Just waiting on more machine nylon screws washers and bolts, this to float the output.
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Re: Server converted power supplys.

Postby sureshot » 10 Apr 2017, 21:04

Tried the 1200 dps unit up to around 350 watts +/- losses in lamps and cables. A 30 Amp terminal block melted, replaced it with higher current direct connection and took it to 500 watts in 50 watt lamps. Very cool and quiet at this level, the fans operation seems very linear in terms of speed. I noted case temps very low.

Connection to my radio with the 1200 watt units causes some raised noise in S points. But my antenna is close to my radio, I'm fairly confident on an outdoor antenna things would be better. The 460 and 750 watt units didn't create any adverse noise. I've not got a big linear amp at the moment, but I'm sure these would work a treat. Any feedback on others uses of these hp dps series units welcomed. Or any other mod's youve tried !
Still have to give the 24 Volts two in series a try.
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Re: Server converted power supplys.

Postby Admiral » 18 Apr 2017, 21:03

Just for the record, I was hunting about for a PSU to fire up my old Kenwood TM/V7 as I needed a few watts on a certain frequency, anyway, forgot that I had bought a PSU off of you sureshot, hadn't even opened it, well got it out tonight 8 months later and it's neat, very quiet, and didn't murmur banging 50w-60w out on VHF, a crude calculation in my head thinks about 12-14 amp pull. I've completely forgotten what it is supposed to do, but obviously a lot more than 15 amps. Cheers and beers.
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Re: Server converted power supplys.

Postby sureshot » 18 Apr 2017, 21:54

Admiral wrote:Just for the record, I was hunting about for a PSU to fire up my old Kenwood TM/V7 as I needed a few watts on a certain frequency, anyway, forgot that I had bought a PSU off of you sureshot, hadn't even opened it, well got it out tonight 8 months later and it's neat, very quiet, and didn't murmur banging 50w-60w out on VHF, a crude calculation in my head thinks about 12-14 amp pull. I've completely forgotten what it is supposed to do, but obviously a lot more than 15 amps. Cheers and beers.

You didn't buy it off of me Admiral, I've never sold a single project to anyone. If i remember previous posts it was sec123 that sold you one. There are reasons i wouldn't sell to anyone. But projects you build and use yourself are fine. My posts are references for others competent in Electronics to try for themselves. And any future mods i do i for my use only. Glad to see you could make use of one Admiral.
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Re: Server converted power supplys.

Postby Admiral » 18 Apr 2017, 22:05

Ah, okay, well then thanks sec1223, I finally got around to using it and runs like a charm, if you still remember your spec from 8 months ago sec1223 then I'd be interested to know how far I can push it.
And on my particular VHF set there was no noticeable extra noise created from this thing on NFM either, it always was an S1 on standby and still is.
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Re: Server converted power supplys.

Postby sureshot » 18 Apr 2017, 22:13

If anyone would like any more information on converting high current server power supplys, check out the RC forums threads. There are many with stacks of info you can trawl through. Although i still modify the odd unit, i rarely use them past testing. I've boxes with smps and linear psu's going back over six years of tinkering. There are plenty of references on youtube as well. You'll find some smps will work fine, but others can be electrically noisy. For the RC guys noise is no problem, but for radio use its an unwanted pain in the butt. But there are a lot of quit ones out there. Sellers on ebay have got wise to people wanting them for alternative use, and sadly that's reflected in the price there asking. But if you know or have a friend in the IT industry !
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Re: Server converted power supplys.

Postby sec1223 » 20 Apr 2017, 10:26

Admiral wrote:Ah, okay, well then thanks sec1223, I finally got around to using it and runs like a charm, if you still remember your spec from 8 months ago sec1223 then I'd be interested to know how far I can push it.
And on my particular VHF set there was no noticeable extra noise created from this thing on NFM either, it always was an S1 on standby and still is.


they are 82A@12V, so probably 65-70A@13.8 at a guess
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Re: Server converted power supplys.

Postby Admiral » 20 Apr 2017, 15:58

sec1223 wrote:
Admiral wrote:Ah, okay, well then thanks sec1223, I finally got around to using it and runs like a charm, if you still remember your spec from 8 months ago sec1223 then I'd be interested to know how far I can push it.
And on my particular VHF set there was no noticeable extra noise created from this thing on NFM either, it always was an S1 on standby and still is.


they are 82A@12V, so probably 65-70A@13.8 at a guess


Jesus H. No wonder my 55w NFM didn't even turn the fan on, didn't realise it was that meaty, or forgot, cheers dude, it's a very tidy and pro conversion job too, looks very neat :thumbup:
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