Hi there, Wouldn't the MARS mod render your KX3 unusable under the new FCC advisory note relating to the ability of equipment to transmit out of amateur bands?
I'm guessing you are referring to the FCC taking on Baofeng regarding violating the rules concerning commercial sales of "type accepted" equipment. There is no prohibition against amateurs possessing or using equipment capable of out of band transmissions; the prohibition is against actually transmitting where they are not authorized. The MARS mod does not affect amateur use of the equipment within amateur bands. US amateurs are free to design, build, modify and operate their own equipment as long as the equipment meets FCC emission standards. That's why kits can be sold without going through the "type acceptance" approval process. The kit isn't a radio until it is assembled, and then it is up to the individual amateur to make sure his equipment complies.
But, some time ago I read the NTIA (the agency that regulates US Federal frequencies) had ruled that MARS members had to use equipment that complied with NTIA regulations, which did not include modified amateur equipment. I am not a MARS member and I don't know how that played out. The NTIA regulates Federal government frequencies, including military, and the FCC regulates civilian frequencies.
Wally