I've got two analog, NTSC, mini (3-6 inch) portble (13.6 volt) color TVs, a Sony KVX370 Indextron (4"), and an Action 5503 (6"), whic is similar to a Roadstar 5503. Both are currently working apparently as designed.

B&W they are just fine. But color renditionis terrible. After recent repair by
Andy Cuffe (dead power chip) the Indextron is better than it was.

But the color is awful. There is no way to get all hues correct at
all saturations. I did not try adjusting the Sony, since I haveno board extenders, and had to leave it to Andy. I did thismorning adjust all
the controls I could find on the Action .. there seem to be only two
internal ones, which are CRT bias adjustments for R and B (I think!).
They improved it a bit. This set seems to be a Trinitron like CRT and
uses a Mitsubishi M52303ASP one-giant-chip works. The user controls
on neither really work like the old fashioned ones did.

So the questions: Does anybody know WHY they are so awful?
Does anybody know of similar ones that are actually good?

At one time I had a tiny "RCA" portable ATCS-NTSC set that had fine color both in ATSC and NTSC. I broke it and the replacement, a Digital Prism brand one, actually gets good reception on my patio and has excellent color, but its ATSC only. LCD of course.

There was no reason that the old ones could not have been good color.

I'm not goign to be any help here, but I am curious what kind of display is in the Action 5503.

I have the same Indextron also repaired by Andy about 10 years ago and it came back great. But lately it is fading again with a washed out picture. Andy fixed a lot of cap leakage damaged traces and all of the caps but something is failing again. The CRT beam focus (beam landing adjustment) is the critical starting point. Get a red screen all red. They are like a reverse version of a striped vidicon color camera of the 80's. Get the beam landing to start. Below is my Indextron on the left next to a Sony KV-5000.

My other micro set is a Panasonic CT-3311, a 2.6" color CRT and great for the first hour. Then the dreaded vertial collapse. A great pic when it is live. Stay tuned.

I'm not goign to be any help here, but I am curious what kind of display is in the Action 5503.

The Action display is an extremely ordinary Trinitron type tube, 5.5
actual display diagonal.