Another Ion Laser Question.....well maybe a couple....

[Electroncloud]

Hi Folks,

Just picked up two Spectra Physics 164s. One is an Argon the other is a Krypton. Anyway, they are both the old style with the blue and black painted cabinets on both heads and the power supply. The model number does not show a '-0x' suffix after it on the serial number/model number stickers like the later versions did. Like model 164-09 or something. Only got one power supply with them and it's the older Spectra Physics 265 without the "master" key switch and the white front panel instead of the black panel. I'm going to guess these are from the early 1970s. Can't be much later than 1975 or so.....

The tubes in both heads were replaced back in the 1990s, sometime around 1997 or so. I tested both tubes with the Oudin coil and they are definitely NOT up to air! The cathodes look very good, no black or white powder around them at all. They both show a violet/white discharge with the coil.

My first question is, since there is no -0x suffix after the model number on the aluminum identification stickers, and the new tubes in them do not have the original Spectra-Physics stickers on the tubes, how else can I identify which tube is installed in these heads? I cannot image that they would have deviated too far from original.....but maybe?

Were the earlier versions only 28 or 30Amps instead of the later at 38? Were the early lasers mixed gas?

I guess I need someone who knows the serial numbers and how they would have been and to go from there?

Any help would be great!

Thanks,
Andy

[mixedgas]

Did you look on the tube sticker where the ash number normally is? Its not on the PSU case, its on the tube. On the Krypton power supply is there a small region of the current meter with a four colored band ? (red-yellow-green-blue) Hopefully Laserman532 chimes in shortly, he worked at the factory.

Can you shoot me a pic of the tube stickers and the glass cathode end bell?

Rebuilt tubes from one typical rebuilder have no stickers.

I can tell what is installed optics wise from the coatings, but I would have to be there to do it.

If there is no number on the tube you have to assume you have lower maximum bore current.


Steve

[Electroncloud]

Hi Steve,

No, there aren't any stickers on the cathode end bell of the tubes. The power supply meter only shows a green band with a "fill" line.....that's it. There aren't any other color bands on the meter to show fill level for Argon or Krypton gas like on the newer style supply meters.

It does say on the front power supply panel that 30 amps is maximum current though. But I'm still not sure which tube is actually installed in both of these heads to know for sure? I'd hate to over drive them, if they are still good.

I'll see if I can post some photos.

Thanks,
Andy

[mixedgas]

28 amps is not going to hurt them.
There is no way to tell without the stickers.
You have to assume you have the smaller tube. That is all you can do.

Assuming you have inspected all the head wiring for safety, cleaned out any mouse's nests etc, and have (with the power off) checked the passbank transistors for blown fuses, all you can do is light them up.
Disconnect the little connector to the fill solenoid in the head before you do. In case the optional autofill board decides to malfunction because the tube has not ran in such a long time.

Turn the current knob three quarters of its rotation and if you have a magnetic field knob, set it about half way. Press start. Do not initiate a fill by turning the key too far.

Do you have access to a manual?

Steve

[Electroncloud]

Steve,

Not for this particular style. I have some notes when I was in college when I last used a 164 to pump a 375 dye laser, but that was long ago. That laser I could run to 38 amps, I could get 6.5W out of it with broadband optics installed.

Looking at the tubes closely, there are some numbers written inside the tube on the white ceramic portion. Not sure if that would be the ash number or not? Here are couple of photos I've attached of both end bells.






I'm not sure if there is any calibration to anything inside the power supply, incase there is a problem there. A manual that covers that type of info would be nice.....maybe some schematics even. Yup, I'll have to check the pass bank first and I'll check the flow switches as well....just in case! I understand it uses the voltage drop across the tube to know what the gas level is inside the tube. Seems straight forward. Doesn't look like either tube has the pump feature for krypton specifically, like I've seen in some other literature.

Since I'll have to get another 265 power supply for the other head, was there a difference with the Krypton style power supply? Or did they just use the same power supply and have a meter on the front to just show the level for Krypton or Argon? I suppose the krypton style supply would have had the features to operate the pump, if installed. Doesn't look like there was a difference here though for these earlier units.

Both these heads have the Litro prism for the rear mirror installed. The "argon" head has the air gap etalon installed as well, although I'm missing the bellows between the etalon and rear mirror block. Also will need some O-rings for the other bellows.

[mixedgas]

Pull the rear mirrors. Aim a incandescent flashlight at the mirror at near normal incidence. Reflect the light onto a white card. It becomes obvious what you have to some extent, unless you have specialized optics, which are rare. There is no way to tell from the markings on the isostatic pressed BeO core.

There is very little difference between the PSUs, it does not adapt to different heads.
One version has a slight interlock difference, but it wont kill anything to interchange.

Steve

[Photonbeam]

When I worked in final test at Spectra Physics in the mid '70's, I remember that tube processing dept. didn't know what the plasma tube would be until after it was built and tested. Then it was labeled as a -07, -09 or whatever. I've shipped -09 spec 18W argons doing as little as 19.5W or as much as 25-28W. Back then, building plasma tubes was a black art. When someone in final test would blow up a power supply and kick off the breakers for the building, the glass lathes would stop and work in progress would be ruined. They finally got tube processing on a separate electrical service. Whoever blew up a laser had to display a small plaque above his workbench that said "Dept. of Arcs and Sparks" until the next tech blew up something, then he got the sign. Lotta fun! Good luck with the 164's - hope you get them working. If you can just get them to start...

[Laserman532]

deep in the cobwebs of this old brain...

the -09 version would operate at 38 amps and produce around 6 watts, specd at 5w
the -08 was a 34 amp version (i forget spec)
the -07 was at 32 amps (i forget spec)
the -06 was 28 amps (i think 4 watts)
the -05 was the UV version with the quartz windows

The plasma tube would have been designated as a 073 -XX (meaning -06 - -09 depending on how well it produced on the test station with standard optics.)

Plug that sucker in and push the start button and see what happens...it will either not start or it will...

[Laser Electronics Ltd]

Hi Andy
If this helps, the rule for all the Spectra 070 tubes is as follows.
The 070 series was developed for all the small frame Ar and Kr ion lasers that Spectra Physics produced from the 70s onwards, the additional numbers that were added gave the bore diameter and bypass capillary size.
This also equated to the output power, ie an 03 designation would be a 3 watt tube with the corresponding bore diameter, the smaller the bore the better beam.
The pictures you posted look like the tubes have been re gassed and reworked, the tell tale is the glass off point of the fill pipe, if you look carefully they differ, on an original tube the glass pinch off is longer and annealed.
The operating tube currents don't really differ that much, the Ar version should run at 30 amps tube current (max) and the field control (magnet at max) should give you 235v Dc measured between anode and cathode on the tube.
The Kr version should run at 32 amps and with the field control set midway the tube v between anode and cathode should be 242 v for optimal output.
The 164 version of this laser was designated for scientific use whereas the 168 version was shorter on the resonator.
Hope this helps.
If you need any more info drop me a message.
Clive.