Looking for a 450V to 500V adjustable power supply for tubes

Alan0354

Super Member
I need finer adjustment than multi-tap transformer. Need to fine tune the operating point.

I think one way is to stack my 0-60V bench supply with the 0-400V supply. Float the 0-400V supply up on top of 60V adjustable supply I already have, to get 460V maximum. That should be enough for all the tube projects. I will have up to 1A of current capability. I can use this all the way to the wood board prototype amp.

But it would be nice to have a 0-500V 1amp supply. It's $680!!! https://www.ebay.com/itm/PLC-AC-220V-to-DC-0-500V-0-2A-Adjustable-1000W-Power-Supply-Regulator-portable/391914472080?hash=item5b3fec4290:g:5uMAAOSw28pZzFQB
 
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I believe a Heathkit SP-2717, IP 17 can be internally adjusted to 500v, but the output cap would have to be replace with a higher voltage type.
The advantage in this type is that filament voltage and bias voltage is also supplied

In the description, this guy states he has the PS running 520v:eek:
https://www.ebay.com/itm/UPGRADED-H...057287&hash=item3af6a1ffd4:g:MTMAAOSwTEJaALxO

I just bought a electrophoresis power supply, that may go to 500v @ 500ma , but the the interweb has conflicting info on this

The unit I purchased for charging caps (forming) on rescued pieces before testing.
https://www.ebay.com/itm/EC125-E-125-Digital-power-supply-cell-gel-electrophoresis-/152771889481?_trksid=p2047675.l2557&ssPageName=STRK:MEBIDX:IT&nma=true&si=lFmFgqa%2FkiSpOsl%2FQ9Nuj4bnODk%3D&orig_cvip=true&rt=nc
I adjusted my Heathkit PS4 to output 450v as the output cap is only rated for that.
 
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I need finer adjustment than multi-tap transformer. Need to fine tune the operating point.

I think one way is to stack my 0-60V bench supply with the 0-400V supply. Float the 0-400V supply up on top of 60V adjustable supply I already have, to get 460V maximum. That should be enough for all the tube projects. I will have up to 1A of current capability. I can use this all the way to the wood board prototype amp.

But it would be nice to have a 0-500V 1amp supply. It's $680!!! https://www.ebay.com/itm/PLC-AC-220V-to-DC-0-500V-0-2A-Adjustable-1000W-Power-Supply-Regulator-portable/391914472080?hash=item5b3fec4290:g:5uMAAOSw28pZzFQB

So you couldn't run straight transformer or the multi tap behind a Variac?
 
Manual regulation.

Most tube amp PS are unregulated anyway, eh?

Guess I sorta presumed it was just for dialing in then it would be taken out.
 
I would worry if one tripped out, it would possibly see reverse polarity across it's output and be damaged.
That's a good point. Nothing a protection diode won't cure.

But I am thinking about the 500V 1A supply that less than $500. Might have to bite the bullet and spend the money.
 
Manual regulation.

Most tube amp PS are unregulated anyway, eh?

Guess I sorta presumed it was just for dialing in then it would be taken out.
That is true, I do have variac, so that's not so bad.

Only concern is safety. You know how it is on the bench, things all over the place and exposed live wires can be dangerous. It would be better and safer to have a small, self contained unit instead of transformer, rectifiers, caps all over the place. Building a separate supply does cost money also, a big ( 1A) transformer is like 500VA, then all the caps, choke..........cost do add up, easily $200 when all said and done.

On my little bench, real estate is of premium. It's a mess as is already.
 
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That's 10 times the current of the Heathkits. Lethal, even the one I bought would kill. The Heathkit was not quite powerful enough to power one channel of my Citation II for testing.
 
That's 10 times the current of the Heathkits. Lethal, even the one I bought would kill. The Heathkit was not quite powerful enough to power one channel of my Citation II for testing.
Yes, I expect the 0-500V 1A supply will be good all the way to power both channels of the prototype tube amp already. I don't have to worry about the power supply, concentrate on the signal path first. That's why the more I think, it's not so bad. Very clean and small.

Building one with transformer and variac is a lot more dangerous unless I put everything into a seal container to shield all the exposed wire, but it's still going to be big......and more importantly, take up too much time to build one..........and is not exactly cheap. When all said and done, it's going to like $200 or more.
 
I got the supply, but the built in safeties prevent using to charge caps, I received the first one damaged, I was able to get it working, it will be the one I experiment on, and apply the changes to the second. The power supply goes to 575v @ 500ma
 
I received the supply, but it has a loose piece inside, I opened it and found one piece of the aluminum heatsink that supposed to be on a bridge rectifier is totally detached as shown in the picture.

HV supply loose piece1.JPG

HV supply loose piece2.JPG

I am writing to the seller to get an exchange. It is too hard to open it up to screw it back on. It's behind the toroid and MOV even if I remove the board out, it's not something I want to take a chance in ruining it at the process of fixing it. I'll update the status.

The packaging design is not good, I took a long look whether it is possible to open it up and tighten the screw, my conclusion is NO.
 
Actually it looks like it would be simple to replace much more so than a return
No it's not. I took a really long look, I literally have to disassemble the whole thing to get to it. Really disassemble the whole thing!!! there are edge soldered pcb in the way, lots of wires going back and fore. Even if I am willing to do it, it's going to be hours to do it and what if I bread the edge soldered board, that will be impossible to troubleshoot without schematic. I don't need that.

It's a lousy packaging, everything is hinging on other things, you move one, you have to move all. The chassis is like a cradle, parts have to be lifted out from the top, no other way. It's not like I can remove the front and back panel and access to the part.
 
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