Cheap high current power supply option

Most people like a bargain. Even those who aren’t short of a bob or two, which is clearly evident by the number of locals I see shopping in our local Aldi and Lidl in their designer tweed waistcoats and caps, and frequent visits by royalty to our closest Mole Valley Farmers. So…

I just wanted to highlight a cheap option for power supply sources for radios. Some of you may already be well aware of this, but for those who are new to radio who are looking for a PSU to power their mobile unit at home and are struggling to fund the cost of a new dedicated CB/Ham PSU this could be an option for you.

Repurposing HP Server PSUs

There are many guides on the net if you do a search for ‘HP Server PSU for Ham Radio’, including quite a few how-to videos on YT, so not going to do a massive write up. Just few notes on a very basic one I have done for home in case it helps anyone later on.

I chose to use a lower wattage PSU because I have no need for a 100+ or even a 60 amp output one at this time and consider myself environmentally conscious. The one I chose is specked at just 38.3A output. For those who do need more power the second-hand costs for the higher wattage units are only very slightly more than the low wattage ones.

The PSU has a spares part number of 511777-001. There is at least one video showing this part number PSU being repurposed on YT. However, even though the part number was the same as the one in the video, the model number of the unit I acquired was different, mine being a HSTNS-PR17, not a HSTNS-PD14.



A simple jumper wire soldered across the first and fourth (shorter) connector would not power the unit on. I had to solder in some resistance across them for it to do so.. this trick is shown in a few how-to videos for other HP PSUs (not really a trick if you think about it, it’s needed because the servers these were installed in do not have power buttons directly connected to the PSU, they have a path through the main system board between the PSU and power button on their Ops panel which is another little separate circuit).

The resistor value I used was 480Ω (actually used two 240Ω in series as that is all I had to hand). The output voltage read a rock steady 12.2V which was the right side of 12V for me and well within the upper and lower specs of the 6900n I’ve bought to get back in to this pastime.



I soldered the rig power lead to the PSU terminals edge connector. Interestingly when I measured the voltage at the plug end of the wire before plugging into the radio it was reading a steady 12.3V, so gained 0.1 where I thought I might lose a little if anything. So happy with that.

I mounted inside a discarded IBM tape drive chassis which I had another project housed in last summer. Just held still with a couple of cable ties and one screw so that it was earthed to the case. The gap in the front of the chassis I had previously filled with a couple of perforated metal media bay blanking panels from an old RS/6000 server. It’s much larger than the PSU unit, I could probably fit a couple more in there, and I might fit an additional higher output one along with it at later date.



For those who might be worried about noise on receive, there does not appear to be any. I have a constant high level of background noise as many people do at home now. However, I connected the rig up in the car and the have the same level and sound of noise there too, so no significant noise is coming from the PSU.

For me all parts I used cost nothing, they were being skipped, and I did the little soldering at work. But for most people if purchasing you should easily be able to get a used PSU and resistors from fleabay for under £10 in total. Yes you need a soldering iron, solder and multimeter, but if you don’t have these and can’t borrow them from friends or neighbours, the total cost of buying them new will still make your whole project probably cheaper than a new 30amp PSU and are useful tools that you are bound to use again if you continue with radio experimentation in the future.

Hope my waffle helps someone save a few pennies. Even without doing the internal mod to up it to 13.8V this is a much better option than trying to run your rig off a model train controller or a laptop PSU (yes I tried the former when I started back in the day, I am sure I wasn’t the only one, and won’t be the last).

Disclaimer and warning
These PSUs can pack a punch from the output connectors, be very careful not to short them and that you have a fuse inline with kit you are connecting. The caps inside can also store high voltages even after the mains supply has been disconnected for a while, be very careful what you are touching if performing internal mods to increase the voltage. I do not accept blame for injury to yourself or your equipment, if you go ahead with this or similar project you do so at your own risk.

Nice writeup.
I have used them in the past and yes they do work well.
In fact i have sold 2 on the bay in the last 2/3 months and have one old unit on the shelf but not looked at it yet but might just as you have brought the subject up.
Love the pink.

Great posting Neal.

Seems I have a brother in arms with regards to a good waffle
(Do love reading a long posting!)

I've also used similar switch mode PSU's in the past, again like you without any noise interference whatsoever. I like such units in that if they go down they'll not put out a single volt so you know your rig is protected. Get a voltage regulator circuit go in a traditional supply and your rig goes up in smoke! (Even if it has 'crowbar' protection circuits you can guarantee that rig will blow way before the so called protection fuse!) Of course there can be exceptions.

As you say you can find this info about on the old internet but nice to have a write up here on Charlie Tango.

I use a 'proper' Sharman unit nowadays, but it's still a switch mode and considerably smaller and less room warming than a transformer supply. Much cheaper too!

Again, thanks for the posting. Will definitely be useful for some members.


All the best,
Victor

nice post! got myself 1 of this last year for multiple things, and i love this cheap psu. bought 1 at marketplace in holland for only 10 euro`s. for my FT-817 i use a Maas SPS-330 II by the way. also a cheap 1, but with some more options.

I have the HP-DPS800GB (i think). On ebay there is/was a guy selling connectors for it.https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS8umB1YxULR_TctJy-2BsWtnhlQ-uLXbfeoQ&usqp=CAU
I bought such a connector and soldered some, so now i can just put the connector on the spare one i have laying around if this one goes up in smoke.

Also have tried some chinese PSU's for LED strips, but gave a lot of humming spound.

73


Edit: Sorry, it's the DPS600

Just spotted this on the bay.
Thought it was a good idea.
https://www.ebay.co.uk/itm/Yaesu-SP-20-Speaker-and-Power-Supply/164694402302?hash=item26588d24fe:g:oEAAAOSwDMRgIqr6

Well as a retired PSU designer, both linear and switched mode, I would just like to add the folowing (in no particular order) 
 
Using a PC/Server etc PSU from HP, IBM, Lenovo and all major brand makes then they will comply with all relevant safety and other standards so no problem here. 
 
Switched Mode (SMPS) depending on design will only deliver a reliable and stable voltage when correctly loaded.  The OP has found in his case 480 ohms achieves an acceptable 12V.  An oscilloscope would be required to confirm the actual waveform being delivered.  Exaggerated example would be 0V-24V-0V-24V .... = 12V measured on a meter. 
 
For radio kit we are extremely sensitive to both conducted and radiated noise.  This users can judged but a PSU that is OK to power a PC might not be "perfect" for radio kit. 
 
All the above said using "available" PSUs *IS* part of the hobby in getting your setup up and running to your quality, price and noise performance criteria. 
 
So yes go experiment with any PSU but be aware there may be "unseen" stability and voltage variations unless you have checked them thoroughly.

I looked at this as an option a while ago, and was very tempted. Then someone dropped a Astron 50 amp PSU on me in a trade deal. Set it up under the desk, sits there doing its stuff with no noise or problems. Doubt I will ever need 50 amps. But it is large, and a real ball cracker when picked up! Great write up, thanks for the info!

53 Prefect wrote:

I looked at this as an option a while ago, and was very tempted. Then someone dropped a Astron 50 amp PSU on me in a trade deal. Set it up under the desk, sits there doing its stuff with no noise or problems. Doubt I will ever need 50 amps. But it is large, and a real ball cracker when picked up! Great write up, thanks for the info!

Without specific model details then this is a traditional linear PSU with analogue regulation.  For many the typical "bee's knees" of a traditional PSU.  Pretty pure output, no HF switching noise but all this comes at a weight, size, volume, efficiency, heat/cooling requirement, and ..... 
 
Switch mode power supplies are not to be scorned at though.  The real secret/trick is to have an SMPS specifically designed and testes to and for a specific application.  When this is done the designer can cater for and design out many issues associated with general purpose/stock designs.