Coherent I90 - Sagging Filament - Help required please?

[Laser Wizardry]

" 15 characters"

[swamidog]

i have seen that "experimental power supply".. i'm a little scared to be around it, even when it's not plugged in. ')

...experimental power supply that had less than a dozen components, but the night it died seems to actually have been a loss of coolant incident involving a bypassed flow switch and an alcoholic laser operator......

[Laser Wizardry]

" 15 characters"

[mixedgas]

We don't talk about that design, (EM... ER... Coherent's project "HI-LITE"* reduced cost laser system, for those old folks who know how one works..) While it works well, the "Hi-LITE" clone lacked certain basic features to protect the tube, such as negative feedback. My newer 21 component version is much better, features adjustable current and tube protection. The 21 component design fits in the head, under the tube, too.

45 amps!, What were you THINKING? We'll talk about your improper attitude to such a nice 7-8 watt tube later. It must have been doing 10-12 watts!

Karl's supply had the factory ferro-resonant constant power cathode transformer, so it was not a design error causing the sag.

Funny thing, they let version one pass through security because I explained EXACTLY what it was. It got cross country on a flight before some one decided to open it at the local distribution center. It was the local PD rummaging through FEDEX with FEDEX's permission that opened the box. I did have it built in a "Highlight" rack chassis, it looked perfectly commercial before being "FrankenSteined".


Bulk Tungsten cathode alloy is unique. It has phase changes with respect to temperature. So first its brittle at room temperature, gets soft when barely glowing, then gets tough at operating temperature.

* As for High-Lite , it is a novel way to run a tube without a linear passbank, thus making the laser very affordable... But if you do it wrong, or ignore the fill system warning light, you can end up with a dead tube.

Steve.

[142laser]

I ran an old Laser Ionics 10 watt laser with a broken bore segment upside down for a year or so...it would not discharge right side up as the bore was blocked. The worst part was the look of it.....feet in the air dead.

[LaserCo]

I have 'fixed' a sagging filament on a NEC GLG-3030 (small aircooled head like an omnichrome 532) by smacking it on a doorframe with a guestimated angle and force.
It moved the filament perfectly into position where the beam passed dead center on-through it again

[mixedgas]

I have 'fixed' a sagging filament on a NEC GLG-3030 (small aircooled head like an omnichrome 532) by smacking it on a doorframe with a guestimated angle and force.
It moved the filament perfectly into position where the beam passed dead center on-through it again

While I applaud your effort, smacking a I90 is probably going to result in holding a jagged, baseball bat sized chunk of ceramic pipe. The Alumina is strong in compression, not shear. The thought did occur to me of heating the cathode to the "soft" region, and dropping the head in the right direction a few times, but if its the support and not the cathode itself that is bent, well.... I imagine the results would not be pretty. Besides, one man's small drop is another man's "Bungie Jump".

Smog, I have a few spare, small, cathode transformers without the constant voltage feature, however they do weight a bit, and its not a small pond....
I think they are worth about 5$ in scrap metal.... Let me know if you want one before I use it as an anchor for a small Kayak. You would hook it to a variac and under drive it.

Steve