first light: my SP168 actually works!

[Skyko]

I really had no interest in cranking the tube up to maximum power, rather I just wanted to see if it worked and how easy it was to start. I am happy on both accounts. I will leave it to gooeygus and his 3 phase and 265 exciter to run it full blast. Still, at lower wattages, it seems to be running just fine on this switcher and phase converter for the small amount of time I have had it going.

[mixedgas]

[quote=LaserLover;83361]A sagging cathode is physically a sagging cathode. If you crank up the laser tube power too high for too long the cathode filament can sag/bend/distort in such a way that if it sags into the plasma stream within the resonant cavity (between the HR & OC mirrors)


For the record:

too hot she sags , looses emitting material, or burns out.

too cold she just sags.

Tungsten has a butter soft phase at 700-800C. Once you pass 850 C it gets stronger again. And drawing plasma actually chills the cathode, pumping electrons off it removes energy and it gets colder, but that is a secondary effect compared to sagging. A proper cathode tranny self regulates a bit, but you should not push it.

Just right is 1100-1300C, depending on material, barium doping, and manufacturer. Only way to measure is a tube test sheet spec with a ampclamp and rms voltmeter, or a wierd hard to find device called a comparison pyrometer. The pryometer lets you look down the bore through the brewster window and get a temperature, it works on ratios of emitted wavelengths.

Steve




Steve

[GooeyGus]

just for the record, when the little remote interface said 1.1W the laser was doing just under 2.5W We didn't want to take it higher due to the phase conversion, but the artificial leg was holding strong at around 220V

[GooeyGus]

Here are a few pictures.... I'm taking it up to the shop tomorrow and hooking it into the 3-phase so we can really give her the juice. Hey Steve, do you know if there is a current shunt anywhere on the biophysic power supply? Anyway... sorry for the less-than-stellar quality, the pictures of the laser running were taken on my iPhone. The others were on my good camera. In the pictures the laser is doing a little over 2W. I'll get some high quality pics of it running tomorrow

[Laserman532]

not to throw some dog shit in the punch bowl......but...... the cathode appears to be hot shot to hell and back HHHHHmmmmmm- i will be very interested to find what the tube volts measure. That cathode has been through some troubles in his life Oh well, it does start and lase...i'll shut up nao

[Skyko]

You mean the discoloration in the cooling jacket? That is just residue from the water that was left in there. The head only has ~525 hours on it and I really doubt the cathode is *shot* as you say.

[Laserman532]

You mean the discoloration in the cooling jacket? That is just residue from the water that was left in there. The head only has ~525 hours on it and I really doubt the cathode is *shot* as you say.

hours dont mean anythig to me- Ive seen really effed tubes with zero hours on them...any what I meant was Hot Shot- A quick fix for high tube volts, I didnt meant the tube was SHOT...i meant hotshot (ask gooey...I explained it to him on the phone) We talked about the cathode, it appears to be an anomoly from the photograph what I saw Dont be fooled so much by hours on plasma tubes it all depends on what KIND OF HOURS were put on them I think it will go just fine...Good Luck!

[GooeyGus]

Yeah after we got off the phone I had a chance to get a flashlight in there and it looked pretty clean. I think the way the flash lit up the photo made the inside of the cathode bell look black

[Skyko]

Ah ok. Ya I am pretty sure the tube will run just fine on the SP265 since it works so well on the biophysics switcher. I do have some concern for it breaking when something falls on it. Gooeygus likes to stack things up really high next to his lasers

[GooeyGus]

Well I didn't get the laser up and running on the 3-phase today.

We had a lot of issues. The water is a long way away from the outlet. The water is NOT a standard hose outlet, but a 'sink' fitting which is like a 3/8" compression fitting. I got all those issues taken care of and we had the water lines ran and the laser plugged in. It was about 8:00 when we decided it was time to fire her up, got the water running. The problem was that we just needed a length of standard garden hose with the fitting to run to the drain. We didn't have any left so we improvised. We turned the water on and had good flow and everything but we were dripping a bit from the 'water out' line. That's when we decided to call it a night and get the proper hose for tomorrow before we actually turn everything on.

The good news is that the three 'power' lights lit up when we plugged the PSU in, so at least we know SOMETHING works. Haha... tomorrow we'll really find out if this 265 works when we throw the switch on it and give the laser the juice.