Hello, I'm gonna try and give you all some tips from my experiences with resurrecting/learning how to build a PSU to power air cooled argons.
First a question for Hemlock Mike, where on the tube would you advise hitting with the oudin coil's spark?
I used to weld plastics and we used Oudin coils to test our welds out, I would point the tip along one side of the weld and hold my other hand over the opposite side
and run it along the bead, you would want to do this fairly quickly as the spark wanting to go thru would eventually go thru just like how that will happen on a glass plasma globe over time....!
I have tried my oudin coil on some hard to start tubes and really did not have any luck
I'm thinking another option to an oudin coil would be to use some tin foil taped over an "old school" CRT television's screen, with a wire attached to it.
I don't think them little plasma globes are gonna have enough juice to do what you're trying to do here. Another option might be one of them barbeque grill peizo starters, I'd do a direct connect with one of those somehow.. OR how about trying to use a disposable camera's photoflash cap's juice - or - its trigger coil output.. OR, try a Model-T Ford coil out, I was disappointed that they are not worth much money when I was thinking of selling one
Vintage Ford Model T A Magneto Ignition Coil Wood Buzz Box Dovetailed Logo | eBay
Be creative!@
I'd be worried about zapping the Op Amp'd light feedback board while doing this, if it has one. I know I had removed it when messing around like this, of course this all depends on what method you are going to try also.
The Filament (5-4-3-2-1, Ignition):
On some tubes you can see it and the lovely glow of plasma around it while the tube is running or starting, others you simply cant see it and to get an idea of how hot it is running you would want to peer down the bore or try to see it within the head.
I found that tubes that had a higher cathode voltage (over 2.8VAC) would become harder to startup.
I had built a power supply that I used for my testing/rejuvenation/running/etc, I had tapped into it and used various methods to adjust the filament voltage or turn the filament on and off.
I liked it when the filament was orange with no yellow. On a problem tube I could coax it to ignite sometimes by strategically flicking the filament ON while turning up the anode voltage - or just having it at the right voltage (number of rotations on the ten turn pot, I was not actually reading a voltage) and flicking the switch to ON. While watching what was happening as it striked I could get a feel for what was happening and could vary the Cathode being switched on - or the drive voltage and sort of have some control.
The Filament (-BLASTOFF!-):
OK, She's running now! There may be a beam, there may not be and if so it's a whole 'nother problem
What's important at this point is what that plasma around the filament looks like.
What I would like to see is a nice purple-ish glow, I'm guessing at around 445nm.. with NO little "sparklies" happening. Remember when I said I liked an orange glow on it before ignition is hit? Well, on "problem tubes" if we are into the yellow zone then what might start happening as we increase the drive voltage is these little bright spots would flash along the cathode, more often towards the 2 ends actually, and when things are even worst you would see flare-ups, like quick bursts of fire - OR - sustaining flame-like points.. RIGHT NOW if you see that happening TURN DOWN THE JUICE!! let her idle, let her breath for a long time.. then turn it up again slowly.. after doing this a few times you eventually/usually can attain stability.
It was said in the earlier replies that the person(s?) would start off by running the cathode only, heating up the tube, or point at hand was whether to leave it sit and tick.. my feelings on that are "half and half", On problem tubes I'd sometimes let it sit-n-tick, sometimes for hours
Sometimes I'd have the fan running, sometimes not. I'd usually set it up so if it ignited the beam would hit where I am watching.. by my computer monitor, the tv set etc
If I had the fan running I could use that to my advantage and hear the fan drop RPM's slightly as the current demand increased when ignition was attained (That house I was in at the time had real BAD wiring!) I'd recommend turning the filament voltage down a bit lower if it is to sit-n-tick for a long time, cuz again, I feel it would create problems in startup.
If all seems "GO" and there is still no beam exiting then what I would do first before starting out with a mirror alignment session would be to check out the beam's pathway to see if the filament might be blocking it, on an NECGLG3030 the filament is supposed to be centered around the beam and I had one tube with a sagging filament, I was able to (after crossing my fingers) smack it against the wooden doorframe in the correct direction and in doing so was able to make the filament bend back into place - allowing the beam to pass through it. That tube put out great power, success!
