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Originally Posted by vortalexfan
OK so a little update, I dug out an old B & K Precision DynaJet 666/606 Tube Tester that a friend of mine gave me and I used that to test some of my tubes in my TV including my 1B3GT tubes.
Apparently the most crustiest nastiest looking 1B3GT tube I had in my tube stash which was a Sylvania 1B3GT tube turned out to be the best 1B3GT Tube I had in my stash and all the other ones (including the one that was in the TV when I got it that was marked "VEE" on it that I thought was actually the best tube of them all) turned out to be bad.
The B & K DynaJet 666/606 Tube tester puts a load on the tubes as if they are in circuit when testing the tubes so you get a real world test result as to whether or not the tube is actually good or not so the test results are more accurate.
The interesting thing is that the B & K Tube tester tested the crusty looking 1B3 tube as being almost NOS in the Quality Test and the Grid Emissions test showed no Deflection at all, and the other 3 tubes that my Sencore tube tester tested as "good" the B & K tester tested them as bad including the 1B3 tube that was marked "VEE" on the base (which the Sencore tester tested it as almost NOS).
So it seems I may have found my new go to tube tester...  
Also when I put the Sylvania 1B3 tube into the TV the screen's brightness and contrast improved greatly and is now even brighter than it was previously and the weird focus issues that were going on with the contrast and brightness controls being rotated cleared up significantly as well.
I still need to adjust the vertical and horizontal size and linearity yet but I think Its definitely an improvement over what it was previously.
See picture below for what the picture looks like now with the good 1B3 tube in it. |
Pix looks a bit washed out and it looks like neck shadow is bugging you but otherwise not bad.
As a fellow B&K 606 owner (of roughly 17 years) I can tell you it is a good tester, and also tell you that no tester will give comprehensive real use case testing of HV rectifiers and sweep tubes....it makes a good guide to what is not worth installing but sometimes actually swapping tubes is the only way to find one the set likes.
One small nit to pick: you called the face mask for the CRT a shadow mask... that is incorrect. A shadow mask is a screen mesh found only inside the glass envelope of color CRTs. A shadow mask is placed roughly 1" behind the phosphor such that the electron gun beams must pass through its holes to hit and illuminate the phosphor....the shadow of the shadow mask prevents the beams from landing on the wrong color dots and in unphosphored screen area. You will never see a shadow mask in person unless you smash a hole in the glass of a color CRT.