This camper van of mine comes with a radio that goes up to only 90Mhz. I miss my CBC station at 104.9Mhz. I suspect the Japanese use a different spectrum for FM. Is there any way to tweak the radio to the North American spectrum, or just get a new one?

Get a new radio that does 88 - 108.

The Japanese FM band goes from 76 - 90 MHz. It's one of the few places in the world that has this range of frequencies.
Why, I don't quite know.

You can buy a thing called a band expander, which plugs inline with the antenna feed to the radio. They do work, to a degree, but it's not the ideal solution - and trying to remember what station is what when the numbers are all screwed up is no fun.

Better to invest in a decent head unit that has the complete frequency range.

The existing radio can't be tweaked, especially if it has a digital tuner.

It's good know there's such thing as a frequency expander. I never knew that before. Thank you again Hiace4x4 for sharing your knowledge.
I think it will worth my while to try this gadget before giving up for a new radio. I don't really care if the displayed frequency is off. I don't change stations that often anyway. As long as I could tune to CBC with clear reception, I am happy.
Sam

Most of the time you will get clear reception.

Some of the issues that band expanders suffer from are co-channel interference and intermod distortion.

For the laymen, this basically means that from time to time the radio will sound like crap, depending on where you are!