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In Reply to: RE: How long did you run them in before hitting them with high voltage? posted by PakProtector on February 24, 2017 at 04:19:10
When I first put new to me MV tubes in my system, I run them for about 30 min. Then I hit the high voltage switch to light them up. Yes the ones that are shielded show less glow.
But keep your eyes open for the earlier 866 tubes with no shield, sometimes on eBay or some tube dealers, they really have that beautiful full blue glow.
I just got some ( in the mail ) nice early 872 tubes with no shield, as well I have an early Deforest type 872 tube with no shield and they are very sweet.
Also addind a choke to the the plate of the 866 tubes does 2 things, it makes sure they each get the same current, also the best thing is the sound quality improvement with the choke on the plate. With the 866 type tube I have used anywhere from 60 my at at least 500 ma, to 1 h choke. The triad 320 my at 500 ma does a very nice job and are very reasonable cost.
A very good improvement with the choke on the plate.
I had only one failure. It was a Taylor glob, and I ran heater power for an hour. When I ran AC through it, cathode coating would get blown off in little sparks. Not sure what had happened; by the time an hour was up, the bottom of the envelope was goated in Hg, and the rest of the glass was clear...
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
I have had a number of rectifiers that the cathode coating came off. But they still worked well afterwards. I have a number of 249C tubes like this.
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