I have always wondered if Hallicrafters was responsible for much more than
we give it credit for. Originally, SX meant that it was a Hallicrafters
with a crystal filter, which was the deluxe model.

I think Hallicrafters became the model for manufacturers in Japan, and some
of the early Japanese radio successes used X in their model number. Then,
when cars came out, many had X or SX in the name. Perhaps these model
numbers can be traced back to the success of the Hallicrafters line?

73, Colin K7FM Newberg, Oregon