I recently pulled my 300 back out and turned it on to discover it was dim. I can switch to the different modes and the illuminator turns on. I turned it on and off a few times plus tried a new battery. I titened the screw on the ajuster and the thing came on full power. I turned it off then back on and the tube only cuts on for a short second and then cuts off. I have since reinstalled the knob on the switch several times with no luck. It looks like the switch has a threaded base for some reason. However, I can not find any sort of service manual. Guess this is what I get for buying something that isnt a pvs-14 or other common product with manuals out the arse. Anyone else work on one of these?

I hate to say it but it sounds like the fault is the tube... Like perhaps it is going to air or something... :(

Almost sounds like he has some voltage bleed off like a crack in the potting. Are you comfortable pulling the tube out so we can talk you through a couple tests ?

Yeh, no problem taking it apart if it works. Will be a few days before I can sit down and mess with it though. I am kind of wondering if it is the switch. If I mess with it in that on position it will stay on longer. Weird.

Lets hope for a bad connection or cracked solder joint, switch failing..etc.  

Where did you purchase?(new?)
Any warranty left? I would hate for you to start tearing it open and void any warranty you have left.

Good point Wes. I did not even think to ask if it was still under warranty. I just assumed it was not. Hopefully it is just a bad switch but it seems to me more is going on.

Nah not under warrenty, I got a kliller deal on Ebay with some other stuff. Turns out that it seems to be a simple problem. At some point the battery contacts became coroded. I noticed the issue while screwing and unscrewing the battery cap would cause the tube to light up. I am slowly and calmly cleaining it.

Ok so I take that back... i have cleaned the threads and it still flashes. Every now and then I get it to work and then when I cut it off and back on nada. I have taken it down to the tube... now what?

Koga , Try applying 3 volts to the tube in a dark room from a fresh CR123 battery. If the tube still flashes then we know it is tube related. If not we can dig further into the housing to find the issue. Just make yourself a couple leads off the battery with some jumpers or wire. If the tube does not flicker then we know the issue is in the housing.

Thx, for the help. Did not get to mess with it last night because the wires are really small and I had a couple of beers (bad idea to mess with tiny wires.) Messed with it a bit tonight but it is slow b/c the wires are really thin and afraid I will cut them removing the insulation. Been using the smallest aligator clips I can find but the combination of holding the battery, holding the tube and doing it in the dark is difficult. I keep either dropping the battery or touching the clips together and that is when I dont ground the clips out on the housing. I will have to mess with this more later. I am encouraged doing a search of the net it seems easy to either find a new housing with switch or a new tube. I am kind of hoping it is the housing bc I really like the looks of those ultralite injection molded housings. Speaking of which, the switch in this thing appears to be crap. There is a series of resistors that look like I purchased them from radio shack and soldered them together. I did not do much with my pvs14s in the military as far as pulling them apart but the ones I did see did not look like this nightmare inside.

Did some more work with it tonight. I wound up clipping the clear and red wires. It doesnt work so what do I have to lose? I stripped the heat shrink at the solder and connected both wires. At first no dice but I saw it flicker as I moved the stuff around. I found the trick. I wiggled the black wire and each time it wiggles the tube lights up. I guess the thing is soldered to something inside the metal housing but what? How do I pull it out. Dont worry I am not afraid to break anything bc the bitch is already broken. Worse case scenario I can sell the housing.