With the HTX-100 that aint happening. Not unless you are willing to track down a CPU from one of its more flexible cousins, and track down someone with the skills and equipment to solder a surface mount IC chip.
The magnum 257 is basically the same radio, but will work on CB as well as ham. The only other difference is the SSB filters on it, the HTX-100 uses a narrower filter. There was a few more variants of this chassis, such as the Optima Yeticom everybody's raving about.
There was also a FCC accepted version of this radio made by midland, expandable to operate all the way to the top of 10 meters, but without the FM mode. Those are rare, and cost just as much as an export.
The reason the HTX-100 can be had for as little as $50 is Radio Shack had a policy where they would impose major penalties if one of their vendors supplied them with a radio that could be converted for CB use.
Believe me, I looked into converting the HTX-100, even found a supplier of chips, but the cost to have them burned was well, more than you could just buy a Magnum 257.
