Coherent CR-18U power supply (0-100VDC 0-70A)

Hi All

I found a Coherent CR-18U power supply which from the front panel looks like a 0-100VDC 0-70A linear power supply.

It is a unit from 1979 and has a large 3 phase stepdown transformer to 120VAC and the regulation is handled by a massive array of water cooled transistors.

I think this is more for historic purposes and show'n'tell, than ever to get it running again, its not in a good shape.

Pictures of the unit here: File archive | Kaizer Power Electronics


Does anyone know where I can find data for the rest of the laser system? CR-18U did not turn up much on google. Neither does RCA 67339 transistors that there is many of in this unit.

That PSU is for the Coherent CR series argon lasers, there's some specs and further information on this page>> Laser Innovations - CR Series Coherent Laser

These are all graphite tube heads, I'm not sure there's many out in the wild that still function, if any. They were the first sort of commercial argon lasers. Newer designs all use Beryllium Oxide for the bore material, instead of graphite disks.



Your PSU might be worth something to a collector.

Thank you for that link, that answered a few questions

The unit is in such a bad shape that I will not keep it in one piece, the weight and size of it alone makes it unrealistic. I will however salvage the most interesting parts and if someone sees this thread and need parts from it for a identical power supply they have, feel free to ask for it here and I will see what I can do.

I would try to sell it as-is first really, just list in on ebay for a month or something like that.

The power capability of this thing is great, but i doubt many of the parts would be all that practical in current times.

You could probably make a 100 volt 70 amp lab supply out of it, but then again, who has that much current available from a wall socket and wants to deal with watercooling as well?

Benm said:

I would try to sell it as-is first really, just list in on ebay for a month or something like that.

The power capability of this thing is great, but i doubt many of the parts would be all that practical in current times.

You could probably make a 100 volt 70 amp lab supply out of it, but then again, who has that much current available from a wall socket and wants to deal with watercooling as well?

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Yeah ... anything modern is a much more efficient switching design, rather than the big linear passbanks seen on these.

Could maybe part it out? That or someone with a head may be interested just to have the whole set for display/restoration. Bob Hess?

Holy crap! Look at all those ancient condensers, the bank of TO-3 transistors. I haven't seen anything like this in a very long time, and on top of that, it has led a very hard life.

paul1598419 said:

Holy crap! Look at all those ancient condensers, the bank of TO-3 transistors. I haven't seen anything like this in a very long time, and on top of that, it has led a very hard life.

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I'll just leave this here...

Exactly! And they are RCA transistors! When was the last time you saw an RCA transistor? :thinking:

It did indeed have a a very long life, but a hard ending.

The large 3 phase transformer had damages to its insulation, so that alone was a reason to just let it get scrapped.

I salvaged the meters, some electronics/transformers and the water cooled heat sink, but even much of the standoffs with copper wire, base resistors etc was damaged from rough handling.