CRT needed for my CTC53

[Tony V]

Hi Gang,
I just purchased an RCA CTC53 color portable and need a 18VBDP22 or equivilent. Its the typical low voltage focus (Einzel gun) CRT that was popular in RCA portables of the early 70's. If any of you have one to sell or know where i can buy one from, please let me know.
I thought i had gotten a good deal for $5 especially when i got it home and it played. I had just finished doing a badly needed convergence job and adjusted the vertical height and was sitting back watching it, making sure it didnt develop any problems before i put the back on. After about 30 minutes of playing time the raster went extremely dark. I looked in the back and saw the picture tube neck glowing neon purple. Needless to say i unplugged it immediately. I put my crt checker on it and got no readings except for filiment continuity. The filiments still light but other than that it has no readings. I turned the set back on with crt socket unplugged and hv arced like crazy off of the tube pins like it would if it had gone to air. Since the filiments still light it has me scratching my head since i've never encountered this particular problem before. Can anyone explain if anything else could have caused this besides the CRT going south and why would this have happened so quick? It had a nice picture just before this happened and had good drive on all three guns with good color,brightness and focus. The picture was good enough that i didnt even think of putting the tester on it before it conked. Any advice or suggestions would surely be appreciated.
Thanks,
Tony