HeNe questions

[ultimatekaiser]

They typically last 5-10 thousand hours depending on size and treatment. Most modern tubes are hard sealed, so they don't wake on any timescale that matters, nor do they have to be run periodically like argons, as the tube is glass not ceramic. A hene tubes life is typically up once the oxide on the cathode is used up, which exposes it to the discharge and causes it to sputter bits of it off creating metallic deposits on the mirrors and around the cathode and causing the gas pressure to drop.

The ballast will usually get hot and the tube usually will get a little warm as you run them and that's normal. While it's running or after it's been run recently don't touch the anode as it will be live.

 

[Sigurthr]

I've had a few EOL (end of life) LHR-05-911 MG 632nm HeNes "die" of old age on me because I ran them 24/7 for years as accent lights. Basically they gradually suck in air (almost not worth mentioning on hard seal tubes) and diffuse out (lose to the atmosphere) Helium. When this happens the starting voltage rises and the power supply is no longer able to ignite the tube reliably, but can run the lit tube still well as long as the tube's rated current was in the lower end or middle of the power supply's output current range. I have a bare tube on my bench that does this... takes more than 15kV to ignite, but only runs 0.7mA hot above rating.

 

[ultimatekaiser]

well...the gas doesn't leave the tube generally...it just gets buried under the sputtering and in the aluminum of the cathode usually. you can tell as it starts weeping from the holes in the front of the cathode, creating silver spots and the output drops. I have a couple end of life greens and they still light pretty well. they're just really weak from age unless you up the current some. every EOL tube kinda acts different. but generally 'tis as you say. the voltage climbs too much and the current drops until the tube drops out and cant stay stable. like an old neon sign kinda.

 

[icecruncher]

If my understanding is correct, its when the voltage gets to a borderline amount to keep the tube running and the tube starts to sputter or spark and do other weird things that significantly drops the life on the HeNe.

I had a 24/7 12" that ran without issue for over 3 years without any issue. That's over 26,000 hours.

Found it one morning sputtering and flickering on and off. I thought maybe the driver died.

I asked Sam and he said it was probably EOL on the tube, just because of time run and that the drivers usually don't go out like that. YMMV.

3-4 hours + on battery would be fun though

 

[ultimatekaiser]

Yep that sounds like an EOL tube. Yes typically the larger diameter tubes are rated 10000 hours, but that doesn't mean that they can't outlast that. Just like diodes it has to do with the treatment. If you turn it on and simply leave it running it will generally run longer than if you're starting and stopping it all the time. Another part of it has to do with whether it's hard seal vs. soft seal, as well as the type of getter and cathode used. I've seen that zirconium and iodine stabilized cathode ones that are rated for over 100,000 hours!

Also Reds have a tendency to last longer than the other colors, as to get the other colors and higher powers that usually fill them at a lower pressure and a little more neon heavy I believe to help with those transitions, which is why they're more pink and appearance. IR tubes are the opposite and show up a bit more golden yellow orange colored like a HeCd to facilitate the longer IR transitions.