which chassis was the best ?

[zenith2134]

The comment regarding industrial Tektronix monitors reminded me of another great brand-Conrac. My RHB19 Conrac was a studio set with a lot of hours on it. a 1975 model, with a Rockwell branded USA made CRT. Its chassis was built almost like a tube set, all metal construction with high-quality PCBs.
It took a minute for the crt grayscale to finalize, but I personally ran the thing for days on end with no shift in performance. Contrast and chroma gain could be jacked up with no bleeding edges. It also had a cool underscanning feature, which would create a " postage-stamp " sized image on demand. Lost it in hurricane Sandy.

On the other hand, regarding the 'tube heat on printed board' debate, I had a '66 portacolor with all its original tubes, bought from the original owner, who claimed it never needed service. The CRT 11SP22 was real weak in terms of brightness, and a member here shipped me a new one. After installing and aligning it, the set produced a fantastic picture, with the original tubes-on-pcb design. No cold joints on that board, and it ran hotter than most tube stuff I've used.