HSTNS-PD22B DPS-750UB power supply mod

Couldn't find anything on the internet about this PSU, so experimented for myself.
To enable startup i soldered a 330 ohm resistor between pins 33 and 36. In the picture i pointed out the voltage adjusting potmeter. I could adjust it to 12.9V, which for now is fine for me. For 13.xV i would connect a 10k variable resistor between the right or left leg of the pot (anyway the leg which is connected through a resistance to ground) and ground and adjust that until the output reads 13.8 (or a litlle lower if the OVP kicks in at 13.8v). Read at which value the resistor give this result and replace the variable resistor with a standard valued resistor which is the closest to that value.

I also modded a HSTNS-PL19 according to the instructions of French descripton (translate with google) which now outputs 13.4V (at 13.8V OVP kicked in).
I'm quite enthousiast about these PSU's, 750W(about 55A after modding) for about 20€, no interference.

73

Hi Karel,

Interesting stuff there and I see a lot of CB/Ham/Radio users 'converting' or re-utilising such power supplies originally designed for computer systems.

Why not? It does seem like a cheap source of high current power supplies.

However....

Do they contain any sort of power factor correction?

Do they posses a floating zero point rail?

How does the regulation or switching circuitry react in an RF rich environment?
(Particularly common mode issues.)


I know, a lot of radio users may not have even come across such notions glaringly unaware of any sort of issues arising from utilising them for their radio equipment. 

If a low noise floor or lack of mains borne QRM and ultimately protection of expensive radios (especially HF equipment) is a prerequisite then such subjects are worth addressing.

Heck, even a lot of radio equipment suppliers/merchants don't get this one right and will sell anything currently on the market if there is a demand....particularly the 'cheaper' and thus more profitable items.

We all happily lash out the cash for our transceivers, mics, etc. and it doesn't take long before many realise skimping on antennas or feeder systems is a mistake ultimately forking out more cash for 'better' antennas (the one that's popular or got great review scores apparently?!?) along with that fancy coax cable everyone raves on about. 

Not many though stop and think a while about their power supplies which can lead to many chasing their tails with noise issues, throwing that breaker, blaming the neighbours, the wife, the kids and their charging/power adapters. Quite often it's that 'bargain' power supply that's to blame.

I also shudder to think what would happen to the regulation circuitry if RF current comes spewing back into it.


Good power supplies especially for radio transceiver systems are quite expensive....and usually for very good reason.  


Sorry if that sounds like I'm raining on your parade their Karel as I do love a bit of ingenuity when it comes to the radio interest but sometimes it's worth thinking about the whole picture. Especially if we really want to enjoy our radio pursuits.

I wish you well.

All the best,
Victor

Hi Victor,

I've read about the issues you address, found some measured on the net with an outcome of "no problem" or "acceptable" or "solvable". As an argument taking into account the "whole picture" i'm thinking about the demands put on these units when using them as they were meant to be used, stable, reliable, no interference, durability. Concerning price, there is a very big market for computers, datacenters where these psu's are used, compared tho this we are a very small lot of users, and developing qualitative power supplies just for our market takes alot of cost of development which only can be covered by less sales, so a higher price. I think this is the main reason why "Good power supplies especially for radio transceiver systems are quite expensive."

BTW, I think i'll use some ferrite beads, maybe even some capacitors on the output side (a solution i found on the internet)

All and all i appreciate your concerns, but i'm willing to take the risk or have found work-arounds around some of them. Still, thanks for your input, as always.

73

Hi Karel,

None of my points were meant to be an argument towards your good self but express a note of concern especially also for those who may be reading this posting.

If even the manufacturers cannot address the most basic of issues regards power supply design for the radio user then there's not much hope for the end user where such items are typically 'black boxes'. This is very much the case for items that were never even designed for such use in the first place nor contemplated with repurposing beyond original design.

Unfortunately ferrite beads and capacitor 'fixes' are common place even with the manufacturers but still do not address the issue of mains borne interference (particularly the 'Earth' side of things) especially for the radio user. Most of these type of fixes are also usually insufficient when it comes to common mode currents particularly at RF and could wreck havoc with circuitry not designed to deal with such.

I worked long enough in my career as an electronics engineer to see 'marketing' win their arguments based on price alone and other engineers that weren't worth their salt sourcing material that wasn't even peer reviewed. 'Cheap' and 'that'll do' often abounds.

Again, I wish you well.

73,
Victor

Hi Victor,

I'm studying your arguments, since i'm not an electronics engineer(but automotive) and looking for answers on the net.
Concerning the floating zero point i've found that the AC part of the psu must be connected to "earth", if only for safety reasons. The DC "-" should not have any connection to the case "ground". I hope i have that part correct, please correct me if i'm wrong. Just a question, doesn't this lead to a build up of static electricity? I don't like shocks, i've noticed so during modifying the psu's .

 73

Hi Karel,

You're spot on there with your thoughts but there is so much confusion regarding 'grounds' or what some might call 'earth' especially when it comes to RF work.

In electrical as well as electronic circuitry we obviously have a 'return' path to complete the circuitry and in the past was called the 'common' as in common return path. As you may be aware some cars in the past utilised a positive 'ground' with respect to the common or chassis connection but nowadays a 'negative' is more likely to be used. The 'chassis' was used to save on extra wiring required in cars and in electronics circuitry of old a similar method was used. (PNP transistor electronics usually had a positive 'common' but as silicon NPN devices became more prevalent a negative 'common' was used instead.) Neither have any regards as to a true 'ground' or 'earth' and is simply the return path to complete the electrical circuit.

Nowadays in electronics there is a 'gound plane' on the printed circuit boards usually denoting the negative connectivity or common return. Unfortunately the use of metal components either for RF shielding and/or a metal chassis work plus the use of the word 'ground' has caused much confusion from thereon.

With the words 'ground', 'earth' etc. everyone mixes them up regardless of whether that's an AC electrical safety ground, DC common return path, etc. and once you throw in an RF 'ground' for good measure it all becomes much more complicated than it should first be. When you consider that both AC earth or 'ground' as well as DC component negative paths or 'chassis' are utilised together most take the simple path of connecting it all up and usually for good reason on the safety front.

With power supplies and especially so with switch mode technology 'filters' are usually placed on the front of them and often 'bleed' off noise from their circuitry to the 'earth' connection....seems sensible but now you have all that noise traveling along your 'earth' wiring. (What's especially bad is some manufacturers save their pennies and hence make more profit by missing out these filter components altogether!!) As this technology became more prevalent we all now suffer from a very high noise floor RF wise. Hardly surprising with every piece of wiring becoming a transmitting antenna for all that hash.

Start throwing in RF 'earths' whilst ignoring such safety aspects as 'ground loops' with other electrical 'earths' or ignoring 'neutral bonding' utilised with PME wiring and noise would be the very least of your problems. In fact shockingly so!

I know, it's all complicated isn't it and hence why so many get it 'wrong' even amongst so called design engineers and manufacturers. What hope or chance do we as hobby enthusiasts stand?

As radio enthusiasts we scan the airwaves for piddly little signals in the hope of communicating with each other, usually through an invisible 'smog' of other RF emanations. We can help ourselves by not introducing more 'smog' into our vicinity and be a little more careful with our selection of voltage sources to power up our radios. Some do this by dispensing with 'noise' boxes altogether running linear power supplies (not always helpful as modern 'linear' regulators also utilise 'switching' techniques to save on heatsink costs) batteries and even dispensing with items such a computers...which is difficult when using digital modes or electronic logging. Yet others strap multiple ferrite materials onto everything wiring wise in good hope of alleviating such noises. Others still 'give up' the hobby altogether believing they'll never get past those troubles at all which is a shame.

There are fixes for our good selves and many have written articles or presented ideas for 'cleaning up' our shacks to good stead. Many utilise them including myself especially when you've suffered regular 'birdies' on your radio whilst spinning that VFO dial or the dreaded parallel lines seen on a waterfall whether with a radio equipped with such or through software for FT4/8 etc. Some of the problems are not all that visually/audibly obvious and hence why we keep an eye on our 'noise floor'.


Forgive my waffle up to now Karel but I do know that others may be reading and so all of this is not singularly directed at you but in an effort to provide information overall.

With all those problems mentioned I'd rather not utilise a 'black box' that was never envisaged to be used in an RF rich environment and lord knows how many thousands of hours a 'server' or computer power supply system would have been used for before we get our grubby mitts on them.

Static? Now you're on a whole different kettle of fish regards electricity with many utilising 'earths' on antennas to prevent noise or lightening arrestors for strike protection. It shouldn't be such an issue with a power supply though. (Even the word 'static' has multiple uses and most refer to that for 'shot noise' or picking up the background cosmic radiation....that 'schhhh' noise we hear on the radio.)

Be careful with 'shocks', one may kill you one day....those capacitors in power supplies can hold a voltage for quite some time (especially when 'designers' miss out bleed resistors!) and can be kicked out at quite some current through conductive meat-bags, notably ourselves.


It's been fun Karel, my poor old fingers have had a good workout and in the end it's up to you what you use to enjoy your radio. If a cheaper power supply is your only affordable option to power up your radio then who am I to stop you. Just be aware of some of the problems that could/can arise.

All the very best to you,
Victor

Thanks for explaining Victor. The not liking shocks comes from a trauma in my youth when i peed on an electrical fence.  
All in all i'm quite satisfied with the Yaesu on 40, 20, 2m and 70cm. As you might recall i had a lot of QRM on 11m, which now also seems present on 10m, but not on the other bands. I spend most of my time listening now, learning proper ham etiquette.

73

Ouch! Made my eyes water just thinking about that!  

Glad to hear you're enjoying your Amateur Radio activities there Karel.  

QRM hunting can be the bane of our lives and I still have much on the 11m band but fortunately seem to have cured my woes up at 10m. From what I can see on a local web-sdr they seem to suffer similar so must be something in my area.

I really do hope to catch you on the bands one of these days Karel as it would be great to put a voice to your name and get you in the logs.

73,
Victor