Porta-Color

The main benefit of the in-line gun arrangement is that it simplified the convergence process, and did not become easily misaligned when moved, thus making true portability possible.

This presents a problem for conventional electron guns, which cannot be focused or positioned accurately enough to hit these much smaller individual patterns.

Paul Pelczynski was the project leader in the conception and production of the General Electric Porta Color in 1966.

[1] General Electric (GE) had been working on a variety of systems that would allow them to introduce color sets that did not rely on the shadow mask patents.

Through the 1950s they had put considerable effort into the Penetron concept, but were never able to make it work as a basic color television, and started looking for alternate arrangements.

This meant that the phosphors did not have to be displaced from each other in two directions, only one, which allowed much-simplified convergence adjustments of the three beams, compared to the conventional delta shadow mask tube.

This change, which allowed vastly simpler convergence measures, together with the use of GE's own Compactron multi-function vacuum tubes led to reductions in size of the entire chassis.

GE continued refining this system, up until 1978, which marked the end of production of vacuum tube type television receivers.

The basic technology, however, was copied into GE's entire lineup as product refresh cycles allowed.

[2] In a conventional shadow mask television design the electron guns at the back of the tube are arranged in a triangle.

They cleverly implemented a single electron gun with three independent cathodes, later branded Trinitron, all of which greatly simplified convergence.