What to feed a green hene tube?

Hi,

I have a green hene tube that has been sitting on the shelf for ages here...

It is about 2 feet long, has no markings (but someone has put a hand written sticker on it saying 2.2mw).

It looks like the typical Melles Griot design tube, and has that conductive tape thing attached to the anode and taped along the tube length (this helps with starting, I think...)

Question: How should I feed this puppy? I have just picked up a couple of hene laser supplies, a JDSU model 180T-3100-6.5 (3.1kv out, 6.5mA), and a Melles Griot 05-LPM-340-065 (1.70kv - 2.45kv; 6.5mA).

Without knowing the exact tube spec, is there a way to know how best to feed it? What value series ballast resistor should I use?

Cheers,

Pete

That's a big tube.. I don't know if those PSUs will work.

I'm not a gas laser expert (you want either Daguin or LSRFAQ) but I don't think you need any external components other than the PSU.

If in doubt, ask Steve Roberts aka LSRFAQ.

Both of the PSU's MAY work, but I'd go with the 3.1KV for getting it going initially.

Is the tube removed from its housing? That "strip" taped to the tube is the anode lead. It is there to carry the power to the end of the tube that is away from the rear. If it is still in the housing, you connect the +- to the wires out the rear. If it is out of the housing (bare tube), you attach one lead to the rear and one lead to the front.

You do NOT need to solder the leads to the tube. At these voltages, just wrapped, clipped, or even just lying on the end will work (while you are experimenting). Connect the leads, mechanically, for your finished build

It will run hooked up "backwards" but the output will be lower and it may "flicker." It will also be damaging the cathode so you do not want to run it backwards for long.

Without "knowing" what the tube actually is, you will have to experiment a bit with the ballast. I'd start out with ~68K (ohm). Increase it if it "buzzes."

Many of these older greens have lost helium (and gained oxygen). If you can get a plasma and it doesn't lase, the gas mix may be a problem. I have an older Lasos green in which the plasma is almost "white" (no output). I may make a lamp out of it just to show the difference in plasma color from my lasing green Hene lamp

Peace,
dave

Since I've been taking and posting pics of the argon monster, I figure I'll post a few of this tube...














Cheers,

Pete

Definitely not an MG tube(Unless they have greatly changed the design), the end with the blue wire should be the cathode. MG tubes generally use a 70k ballast.

Solonar said:

Definitely not an MG tube(Unless they have greatly changed the design), the end with the blue wire should be the cathode. MG tubes generally use a 70k ballast.

Click to expand...

Siemans/Lasos/Optolectra whatever they are called these days
made that. A rare German made grene....

You can tell a Siemans because its diameter is always much smaller for a given tube length, and by the way the glass is wrapped over the kovar toward the mirror stem. Also by the mousey grey color of the kovar.

I'm thinking 56-68K Ballast, adjust ballast for best power with no hissing/flickering and with easy starting. The output power will saturate and fall off as you decrease ballast, and as current increases. Keep the ballast R within a inch or two of the anode to avoid HF oscillation. I'd back off a bit from the peak power current, as lifetime runs as roughly I raised to the 2.3 power for a gas discharge tube running in glow. But the lasing I range is narrow, too.

I'm thinking 6.5 -7.5 mA or more for that monster.

Enjoy, Grenes have some of the highest quality laser beams I've ever seen.

Would you please shoot a pic of that distorted ring at the tube end of the cathode under the kapton tape, I'd love to learn what that is...

Solonar, having worked on the line, will end some of my and Sam's SWAGs, I'm sure

Steve