CRT decay

< Don't CRT filaments degrade with use? I've seen this on other < workstation monitors from Sun and HP, typically ones that were used as It the common characteristic of all valves (tubes) with heated cathodes that over time emission will decay and gain(brightness) goes away with it. < big-ticket item, the local TV repairman had cylindrical devices called < "boosters" that could be inserted in the circuit between the plug on < the back of the CRT and the set's CRT socket to extend the life of a It got back some emission for a while but the overvoltage generally killed the tube. < dim picture tube. I don't really know what it did, but I suppose it < was something like a step-up transformer for the CRT filament voltage. That was it's exact function. Poor emision is something I really haven't seen in years on CRTs. Thats due to improved materials. Burnt phosphor is more common. Allison