Smallest all tube portable?

[maxhifi]

As the title says, I's like to tap into the knowledge available here to find out what some of the most compact all tube or hybrid TV sets produced were. I am aware of the 8 inch RCAs from the mid 50s, but they despite having a small screen, are not light. I am also not that interested in owning a transformerless set with a metal cabinet, for safety related reasons.