Conserving our good CRT's

[earlyfilm]

Originally Posted by kramden66

i do have an interesting 16GP4 that reads way high on the emissions and cutoff is good but to get a decent image it needs a brightner and the ion trap has to be pushed as far forward as possible , its touching the focus magnet , my only guess here is that it was rebuilt but not properly.

Mike,

Per the Tung-Sol data sheet

http://tubedata.tigahost.com/tubedat...27/1/16GP4.pdf

16GP4 and 16GP4C use 23 Gausses ion trap
and
16GP4A and 16GP4B use 35 Gausses ion trap

Could be you have the wrong strength magnet if it is a replacement CRT

James

[ChrisW6ATV]

Originally Posted by Username1

I think its beam current, or cathode current (excessive brightness) that kills them....
Anyone know if old airline terminal screens had anything special about the crt's?
Those tubes had to run at higher than home living room brightness..... Were they special....?

I still support some CRT displays in airports (and have been doing so for over 30 years), and I am not aware of the CRTs being more "heavy duty" than standard tubes. Some of the monitors I work on have been in service themselves for over 30 years, but few likely still have their original CRTs, though it is possible. I have done rejuvenations on many of them, and it often gives the tube new life that can last for years.

Originally Posted by earlyfilm

I scrounged an old 6.3 volt transformer from my junk box and wired the CRT to be on 100% of the time... We used this set operating the filament at its rated voltage and always on when the set was off for about 10 years!

Earlyfilm's technique is the key to the CRTs lasting for decades in airports. The monitors are almost always on 24 hours per day, and when I shut one off for repairs, it can take 5 minutes sometimes to even see visible light on the screen afterward, but after 30 minutes they can look nearly new and stay that way.

I also agree that it is the cathode/beam current ability that limits the life of CRTs, not the heat (as decided by the heater voltage). Monitors that are used at high brightness and contrast settings have always had their tubes fail sooner than those we could keep at lower settings.