Test & build a power supply for HeNe Laser tube LG-3217 Toshiba

[Hypernoika]

Hi everybody!

This morning, I bought on a street market located on Mexico City a HeNe Laser tube LG-3217 form Toshiba.

I always dreamed about building a HeNe laser, and now I have a great opportunity to do it

There is only one question : Never I worked with laser tubes HeNe technology. I have experience working with HT generators, I worked with neon and fluorescent tubes, plasma speakers with TV flybacks transformers, Tesla coils... but nothing around HeNe.

Here there are shoots of the tube, I don't know if it is good or bad...

I read the HeNe laser tube need around 1000VDC with low amperage to start... I check this really rich website and the schematics : Sam's Laser FAQ - Complete HeNe Laser Power Supply Schematics

This HeNe tube have a 2-3mw output power as I can see.

A 12VAC input voltage should be good for me, better than a 110 o 220VAC input. So I checked this power supply : SG-HM1

Sam's Laser FAQ - Complete HeNe Laser Power Supply Schematics

I think it is a good power supply, and in the future I can use it with other types of HeNe tubes! So it is very interesting to build one!

So basically my questions are:

- As as you can see in these pictures, the HeNe tube looks good? The stain of metal colour down the getter is good or bad?
- Do you think the SG-HM1 power supply is a good option for this tube?
- Where I can found the flyback transformer used in the SG-HM1 power supply?
- Is there a simple working scheme to test this tube, wich is working on 110VAC? (using chaining voltage doublers Voltage doubler - Wikipedia, the free encyclopedia) or something like that who can match with a HeNe Laser tube LG-3217 form Toshiba?

Thanks for advance for your help!

Regards

Axel.

 

[bloompyle]

Unless this tube is only about 4.5in (115mm) then you will need far beyond 1kV. Most need upwards of 2kV or more.

You also need a pulse of a very high starting voltage of several kV. Most of the larger tubes need upwards of 15kV. This pulse is only a few ns long.

However, and this is a technique you'll also use if you ever DIY a laser tube. You can use a tesla or oudin coil to start it, and use the constant output PSU for the duration of the run.

Tube health? Looks good. You want a metallic getter. When it turns an off white or clear, you have a problem.

Unfortunately, you picked a non-name brand tube. This is likely made by MG or Hughes, so I'd need to know the dimmensions in mm to know exactly what you need.

As far as the electronics ..... I'll pass that on to someone else before I burn your house down .......

Good luck!

 

[ultimatekaiser]

It looks similar to the melles griot 8-10" cavity. I might chide an estimate at 1500VDC @ 6.5mA with a 75K ballast with an 10KV start? Assuming its good. These come from an old laserdisc player. I think they do about 2-3mW if memory serves.

the electrode coming off near the mirror mount that attach to the 'can' inside are the cathode attachments, and the other one is probably the anode since the mirror mount is glass. seems like a cousin to my brewster window tube.

 

[Sigurthr]

If you've still got a flyback or a solid state coil (CW preferably) you can use them to power the HeNe tube as well, with no ballasting required. Just observe run times and keep in mind it isn't good for the tube. Easy way to check to see if it will lase though.

 

[bloompyle]

It looks similar to the melles griot 8-10" cavity. I might chide an estimate at 1500VDC @ 6.5mA with a 75K ballast with an 10KV start? Assuming its good. These come from an old laserdisc player. I think they do about 2-3mW if memory serves.

the electrode coming off near the mirror mount that attach to the 'can' inside are the cathode attachments, and the other one is probably the anode since the mirror mount is glass. seems like a cousin to my brewster window tube.

I can respect this estimate.

6.5mA is fairly common on tubes around 8-24". You'll see 6.5mA a lot for some reason. Output could (based on size alone) be anywhere between 1-3mW, though based on age, 0-3mW

Though the voltage may be a bit low. Underpowering a tube is just as bad for the tube,a s it is the PSU. The tube could flicker, not being able to maintain an arc. PSU's don't like this very much.

I'd recommend a 1.75kV - 2.0kV PSU. If you can find a variable PSU that covers a range from 1.5-2.0kV, even better. They exist, but are harder to find.

Also, to be honest, as humbling as it is .... I know next to nothing about pairing resistors to tubes, so I'd go with the advice above.

 

[ultimatekaiser]

I agree with bloom. If it is in good shape and what I think it is, it could run 1400-1700VDC with a 75K ballast. My brewster uses what seems to be around 1500-1600 and is 10.5" cavity measured mirror to the middle of the brewster window. Depending on the bore size I'd expect around 2-3 mW of red if it was fresh. (My brewster does 5+ with a good mirror and up to a whopping 45-60W intracavity!)