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FS - Searching a home for a pair of Lasos 7890A argon heads

HIMNL9

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Hi, dusting off some centimeters :p of dust from my shelf, i found back a box containing a pair of Ar-Ion heads, Lasos model 7890A.

Those units have a sad story on their shoulders :p ..... they came from a set of 6 old Agfa D-LAB units, that was trashed almost 2 years ago from a big photo company ..... the sad part was that the peoples that trashed them, had already mangled and smashed almost all the units before i found them, including a lot of very professional optics, just for recycle the metals :cryyy: , so i got to save only 3 tubes and one PSU (no remote nor anything other, they wasted also the fiber optic cables cutting them for see if they was copper, damn them) ..... i already sold one of them with the PSU a year ago, so now i have these 2 doing nothing other than rest in a box collecting dust on that shelf.

I took some quick pics of one of them (i was in hurry), if someone want more specific pics, just ask, and i post them in the next days.

I don't know too much about this specific model, only that are multiline "glass bell" units with main tuning on 514nm, and that was produced specifically for Agfa D-LAB serie (a digital printing photolab) ..... they was made for stability, more than for power, so probably you can't get too much from them, maybe 10 or 12mW, mainly in the 514nm wavelenght (if i recall correctly, the 454 / 457nm part was barely 2 mW, and the rest also less) ..... They have their original cable and fan, and over the shutter slider, at open aperture, there's a second slider with an empty hole and a second hole with a polarizer filter in it (in the minilabs they was used with the polarizer in the path, probably without it, you can get some more power, but i don't have a compatible PSU, so cannot test anything) ..... the last time i tried them, before sell the one with the PSU, they was working, but consider that now is at least a year that they don't become turned on ..... does some gas laser expert (*cough*Dave ?*cough* ..... :D) know what they can worth without the PSU, actually ? ..... and also, there is someone interested to buy one of them ?

Please consider that i'm in Italy ..... i can ship oversea, but shipping oversea from here can be a real pain you-know-where, for shipping fees with this weight ..... anyway, i'm cleaning up my messy shelfs (i just realized i have too much lasers around :p), so probably in the next weeks some other things can pop up for sale ..... ;)
 

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ElektroFreak

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No matter.. if they're gas-intact hitting them with a oudin or tesla coil (if you have access to one or the other) will likely get them to fire if they've sat too long.. It might take a few tries, but it's been known to work. Once you run them for awhile they should be easier to start. Those tubes look like they're in nearly new condition, if not new.
 
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HIMNL9

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I looked inside and there's a 10.000 hours mercury time-counter, it say 5000 hours (but it's connected to the fan, not to the tube, so it just mean that the fan was powered for 5000 hours, and the fan was probably always on, also when the tube was not in use, in the minilab, so i have no ways for know how much really the tube itself was used).

In the meantime, i have found some other informations about these tubes, in internet ..... they was rated for work at 10mW of 514nm, with a secondary emission of 4mW in the 454/457nm, with polarized emission ..... also if the sticker on the tube say "max 200mW" of power ..... i'm not sure if this is related to the maximum power that the tube can handle, or if is a generical indication, i only know from documents found on internet that the 7890A Rev.01 units was specifically produced for the minilabs Agfa D-LAB.2, .2+, .3, and Kodak RP30, and that they was regulated for emit a total of 14mW in the minilabs ..... maybe they was using a high power tube in low power mode for have more emission stability in time ? ..... not sure about this, anyway, so i consider them 14mW units, independently from that what the sticker say.

As i've said, the last time i've turned them on, was almost a year ago, and all the 3 was working ..... then i sold one with the PSU, and from that time, i had no ways for use them again, so they remained in the box unused ..... i know that argon tubes needs some periodical firing for keep the efficence, but don't know if a year stored can have caused any degradation.

I don't have a tesla coil at the moment, but i can easily build a low current HV unit in the next days and try to see if they fire up ..... and yes, they looks almost new, they was closed in the box and not got too much dust.



EDIT: just found this datasheet for the 7890 serie, is the more complete that i've found til now.
 
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diachi

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How much are you wanting for one? I've *always* wanted an argon with a glass bell, just so I can see the plasma glowing! :D
 

diachi

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You can either use a step up transformer or find a PSU that is 110VAC. I *think* ( been a while since I've been around much ) that a JDSU 2211/4 PSU will drive one of these as long as you keep Itube at 8A or less.
 

HIMNL9

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I'm trying to find a "hobbyst" quotation for these units ..... don't want to throw them away, but also don't want to ask exagerate cyphers .....

Any gas laser experts that know how much can worth this particular tube, without PSU ?
 




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