Power supplies

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53buick
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Power supplies

Post by 53buick »

Hi All,
I am just setting up my station in anticipation of passing my Foundation shortly.
Being into radio for many years I am quite savvy with most of this but just want some opinions please on the PSU.

I have a few power supplies around the place but I am thinking the best option should be to run the radio from a battery and then trickle charger the battery up BUT reading around it says that the radios perform better at 13.8V than 12V (for obvious reasons).
So this means the batteries are not the perfect source albeit the quietest source.

So, do I run the power supply at 13.8V with a battery in circuit too so the higher current spikes will be absorbed?
Or do I just find the best Linear supply and use that or are the newer SMPSU's quite immune and quiet now especially if we fit filters on.

I wont be running power as I will only be foundation qualified so I don't need much current but I am pre-empting passing further exams through 2021 if I can.
:)
not wanting to redesign my power stage multiple times, get it right first time ideally.

your thoughts please.
Spence
Alan Pilot
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Re: Power supplies

Post by Alan Pilot »

Best bet is something around 25/30 watt future proof.
I run a linear but many run switching without problems.
53buick
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Re: Power supplies

Post by 53buick »

Hi Alan,
You mean 25/30A I guess.
I have a 40Amp "Fusion" Switched mode power supply that seems quite quiet apart from the annoying noisy fan (which I am currently trying to redesign) and I have just ordered an old vintage 20Amp linear PSU that is convection cooled.
It is only the current spikes that I am concerned with as I can't imagine ever needing 30Amp steady state current.
Running 10W on HF with an FT450 is drawing 6.4Amps which is higher than I expected tbh and into a dummy load on FM it is drawing 18Amps, very high in my opinion.
I guess with optional extra's I would be better off with a smaller separate linear supply too.
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Re: Power supplies

Post by Alan Pilot »

Don't know where "watt" came from lol.
My 30A linear had a noisy fan that soon got changed for a silent computer fan.
I run my Yaesu FT991A along with a MFJ-993B Tuner and 2 small LED strip lights on mine.
It sounds like you have plenty of power to hand already.
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Re: Power supplies

Post by Auldgeek »

You might wish to consider purchasing and modifying a Server Power Supply. For under £20, you can have a 13.5 volt 100A supply.

I modified an HP 1200W server supply a couple of years ago. As stock, it will only provide around 12 volts but a simple mod and you have around 13.5 volts.

You can spend more and tart it up in a case with V/A meters, multiple outputs & cooling fans like I did but it's not required.
I've just ordered a 2nd unit to muck about with.

If you want something off the shelf, the older linear supplies with passive cooling tend to be the best but there's some really decent SMPS around. Go for the biggest capacity you can. You will eventually need it. I've a few supplies, all powering up various bits & bobs.
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Re: Power supplies

Post by DX-Digger »

While you are considering which route to take, one option that should be high priority is an overvoltage protection circuit fitted in the psu. (crowbar circuit)

Using a 12V car battery gives no protection to short curcuit until the fuse pops, this could happen quite late and damage the radio circuit, not all modern radios have a fast acting protection diodes and as I am sure you have seen, many a fuse wrapped in silverfoil etc, (not saying you would ever do that) but
I have seen it done inside Yaesu and kenwood radios, I kid you not.
Have a look on this website it gives you info on adding crowbar protection and fan mods for the EP925 930 psu's
https://pa0fri.home.xs4all.nl/Diversen/ ... 925eng.htm

The above linear psu's are still available from Nevada etc.

Anyway just something you may want to think about as it gets overlooked until it is needed then the damage is done.
Had my psu go overvoltage to 20Volts, so a lesson learned here.
Cheers Mark
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Re: Power supplies

Post by Auldgeek »

DX-Digger wrote: 16 Dec 2020, 14:44 While you are considering which route to take, one option that should be high priority is an overvoltage protection circuit fitted in the psu. (crowbar circuit)

Using a 12V car battery gives no protection to short curcuit until the fuse pops, this could happen quite late and damage the radio circuit, not all modern radios have a fast acting protection diodes and as I am sure you have seen, many a fuse wrapped in silverfoil etc, (not saying you would ever do that) but
I have seen it done inside Yaesu and kenwood radios, I kid you not.
Have a look on this website it gives you info on adding crowbar protection and fan mods for the EP925 930 psu's
https://pa0fri.home.xs4all.nl/Diversen/ ... 925eng.htm

The above linear psu's are still available from Nevada etc.

Anyway just something you may want to think about as it gets overlooked until it is needed then the damage is done.
Had my psu go overvoltage to 20Volts, so a lesson learned here.
Cheers Mark
It's a good shout and definitely something a lot of folk overlook and that's why some of the current crop of China crap supplies are very dangerous. My old linear supplies have over volt & over current/short circuit protection, as does the HP server supply I use. As you've shown, it's easy enough to add & definitely something to consider before you hook up a £2000+ radio, as they don't take kindly to +20v shoved in to them.
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Re: Power supplies

Post by gmham »

Auldgeek wrote: 15 Dec 2020, 19:09 You might wish to consider purchasing and modifying a Server Power Supply. For under £20, you can have a 13.5 volt 100A supply.

I modified an HP 1200W server supply a couple of years ago. As stock, it will only provide around 12 volts but a simple mod and you have around 13.5 volts.

You can spend more and tart it up in a case with V/A meters, multiple outputs & cooling fans like I did but it's not required.
I've just ordered a 2nd unit to muck about with.

If you want something off the shelf, the older linear supplies with passive cooling tend to be the best but there's some really decent SMPS around. Go for the biggest capacity you can. You will eventually need it. I've a few supplies, all powering up various bits & bobs.
What model do you normally go for , like the idea of 100a psu ! Have a 12v HP model one here that I bought of a fellow amateur and it’s been modded. Got a 24v psu here as well to run a 24v linear but could do with a larger amperage version. Don’t seem to see many 24v high amperage ones ?
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Re: Power supplies

Post by Auldgeek »

gmham wrote: 18 Dec 2020, 17:02
Auldgeek wrote: 15 Dec 2020, 19:09 You might wish to consider purchasing and modifying a Server Power Supply. For under £20, you can have a 13.5 volt 100A supply.

I modified an HP 1200W server supply a couple of years ago. As stock, it will only provide around 12 volts but a simple mod and you have around 13.5 volts.

You can spend more and tart it up in a case with V/A meters, multiple outputs & cooling fans like I did but it's not required.
I've just ordered a 2nd unit to muck about with.

If you want something off the shelf, the older linear supplies with passive cooling tend to be the best but there's some really decent SMPS around. Go for the biggest capacity you can. You will eventually need it. I've a few supplies, all powering up various bits & bobs.
What model do you normally go for , like the idea of 100a psu ! Have a 12v HP model one here that I bought of a fellow amateur and it’s been modded. Got a 24v psu here as well to run a 24v linear but could do with a larger amperage version. Don’t seem to see many 24v high amperage ones ?
It's an HP DPS-1200FB. Easy to get up to 13.5 Volts & will supply a huge amount of current.

I've a 300 Watt 70Mhz am to build & that's a 48 Volt supply but I'll sort something out in due course.
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Re: Power supplies

Post by gmham »

Cheers mate will look out for one of those and if you do come across any 24v large amperage power supplies at a decent price please do let me know.
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Re: Power supplies

Post by Auldgeek »

gmham wrote: 18 Dec 2020, 18:27 Cheers mate will look out for one of those and if you do come across any 24v large amperage power supplies at a decent price please do let me know.
Will do John. What spec you looking for as a 24V supply? You could use two of these supplies to get you to 24 Volts but there's work to be done. Pretty sure I have come across an interweb article on how it's done. The supplies for led lighting are available as 24 Volt but you need a reputable brand with proper filtering.
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Re: Power supplies

Post by gmham »

Thanks drew, probably 24v 30 amp or so.
To be honest modding my own stuff is something I try not get involved . Appreciate you could link two together but for a 30 amp supply would just try pick up the one single unit.
Appreciate if you could keep any eye open for a cheap but still decent quality unit .
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Kenwood TS711e
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Moxon antenna for 10/20 mtrs

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Re: Power supplies

Post by Auldgeek »

gmham wrote: 18 Dec 2020, 22:40 Thanks drew, probably 24v 30 amp or so.
To be honest modding my own stuff is something I try not get involved . Appreciate you could link two together but for a 30 amp supply would just try pick up the one single unit.
Appreciate if you could keep any eye open for a cheap but still decent quality unit .
No bother. I'll let you know if I see anything suitable. :thumbup:
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