HGM 5 - new toy for me, if I can get it to lase!

[eyceage]

Check out the postscript at the bottom of this page re:reviving an over-pressured tube...

http://www.electricstuff.co.uk/argonlaser.html

[buffo]

Thanks for the info. I'd read that page a while back while researching an unrelated problem. Honestly though, I'm not quite ready to take such drastic action. (Might try the telsa coil trick though, if I can locate someone close by that has one.) I'd really just like to find a spare tube for this thing...

Adam

[buffo]

Sorry to drag up an ancient thread like this, but I thought I'd finally close the chapter on this laser.

Last weekend I carried this laser to Jacksonville (or should that be "Jags!onville" ) and had David Zurcher look at it. He has a hand-held Tesla coil that will ionize just about any tube. (In fact, on smaller HeNe tubes he can actually get a beam when using this thing to excite the tube!)

Anyway, we sparked and sparked, but the tube never responded. So it's not just high pressure, it's all the way up to air. (shit) This makes the tube nearly worthless. (A re-pump would likely cost several thousand $$$, and because the cathode has been powered while the tube was at air pressure, there may be other residue inside the tube that would adversely affect future operation even if a re-pump was sucessful.)

So I suppose I'll keep my eyes open for a deal on another tube that will fit in this beast. The PSU seems to be in good shape, so I might get lucky. (Still no word back from Steve Roberts about that 903 tube, though if that deal ever comes through I'll be all set!)

Adam

[The_Doctor]

Ouch. Testing with a plasma discharge can work to try to see clues to pressure and gas constitution, but actual sparks can penetrate glass or ceramic. I destroyed a small multimode HeNe tube this way. I had previously tested one with the same device (pulsed coil gas ignitor) and not had any trouble, it ran for years since, but this second time I was careless, arcs hit the wall of the outer tube near the metal to glass seal, penetrating it. It was up to air within minutes. My guess is that yours was already up to air, not damaged by this latest test, but maybe a similar earlier event might have done it. Arcing and glass tubes is BAD, if the arc goes anywhere it is not strictly intended to go.

[DZ]

Ouch. Testing with a plasma discharge can work to try to see clues to pressure and gas constitution, but actual sparks can penetrate glass or ceramic. I destroyed a small multimode HeNe tube this way. I had previously tested one with the same device (pulsed coil gas ignitor) and not had any trouble, it ran for years since, but this second time I was careless, arcs hit the wall of the outer tube near the metal to glass seal, penetrating it. It was up to air within minutes. My guess is that yours was already up to air, not damaged by this latest test, but maybe a similar earlier event might have done it. Arcing and glass tubes is BAD, if the arc goes anywhere it is not strictly intended to go.

They are also pretty useful for starting a high pressure head, but you do have to be careful about hitting the glass as your right, I have heard that it can cause problems. The HGM 5 that I tested has a tube very similar to the tube in a 60X, just much longer. You certainly don't want to hit the glass stems with the coil, but instead hit the bell shaped metalic end. The other unit we tested does not have glass at all except for the hard sealed optics. The coil that I use is an Electro Technic BD-10A. They can be found on ebay now and then and usually go for about $75. I was lucky and found one with a buy it now for $25! Since my last one died, I couldn't pass up the opportunity to get one cheap!

David