[Andrea1951]

I have to disagree! Typically Fast drop in power (one to two days) is tube. Slow (weeks ansd months) drop is mirrors and lens. It sounds like you need to check the 90 degree mirror at output of the tube, and/or the lens in the isolution tube that goes through the back wall of the table chamber. If your not suppling enough suction in table chamber, you may be loosing laser penitration because the smoke raising from the cut, filters the beam. That too would slowly clog up and appear to reduce laser power.

[Exsecratio]

Hi Andrea,

There is a little more to it usually,following is just a small sample,

Instant loss of power without any arcing:

Power Supply Failure (Fuze, voltage regulator etc)
Flow control meter
Door interlock

Power instant loss with Arcing:

Dead tube with volts taking path of least resistance to earth.

Power reduction over time:

Hours:

Water temperature

Days:

Dirty mirrors
Dirty lens
Dirty tube beam coupler

Weeks:

Slow degradation of tube due to age, gas permeation of the walls, electrode erosion inside tube.
Slow failing of power supply high voltage side.

Sadly it's usually impossible to say with certainty what is causing any given change unless a number of variables are taken into account.

Dude,

At risk of upsetting a few RECI diehards the tubes are indeed very good but do tend to suffer from a honeymoon period where they punch well above their weight, yes it's true they can last 10,000 hours but over that time you will find your 150 watt tube will slowly end up performing like an 80 watt tube. A good quality 100 watt will often outperform a RECI over time, sure on spot test the RECI will come out top but that isn't always the best or most accurate view of them.
I'd rather have an 80 watt tube that gives me 70 to 80 watts over 2 years than a tube that starts at 130 watts and after 3 months is down to 75 watts. It means changing files and cutting speeds and all that takes time,time costs so saving money by having a life of 10,000 hours may not actually be the best economy after all once you add in all the fiddling with speeds and feeds as the tube degrades.
Also note a bubble in the mirror chamber of the tube will have no more respect for a RECI than it will a Yingpong Ltd cheapo tube that costs 50 bucks.It will still kill both of them equally well
For reliability RF excited systems are the way to go IF you can stand the running costs of regas or replacement.

best wishes

Dave

[DLDude]

Where would be a good place to purchase a high-quality 80W laser tube that would fit our Rabbit? I'm not sure we're quite ready for RF, but we do value quality if it will reduce headaches over time.

[Exsecratio]

I'd be looking at one of the 3000 hr tubes in all honesty, they are a little better quality but don't have the niggles of the very cheap stuff. The 1000 - 1500 hr tubes are really the basic Chinese junk so you need a make that sits around the 3000 advertised hours and a different make to the el chepos.
Its a really hard call, sometimes you will find tubes that are 1500's sold at 3000's at inflated prices.
The coletech tubes seem to be good and last up to 3 to 4000 hours if you don't cook them. (Ebay)
Go for a full length tube though, part of the problem with Reci's is they gain power through volume and not length when laser generation is really a product of the length of the tube and not so much the gas capacity.
Full length tubes tend to give smoother power delivery whereas stubbys tend to go for grunt rather than finesse
Remember though many tubes are produced by the same companies and just rebadged for distributors, check out the claims and look for a seller with reliable feedback on the model you want. Cole CNC in China seem pretty good and thus far I've had no problem with their stuff. (a LOT cheaper than branded RECI's as well)
I'm sure there will be 10 or so distros running amok here telling you their tube is the best but as I don't work for a tube maker or distributor I have nothing to gain whatever tube you buy

best wishes

Dave