He's asking for legal options and as a ham it's probably not in our best interest to suggest anyone flout the FCC rules as arbitrary as they may be.So, not exactly what you are picturing, but there are plenty of HF rigs that can do all of that. I have an Icom 706mkIIG that can transmit UHF, VHF, and HF. It can also transmit and receive AM signals, which is key for communicating with CBs. Now, it is set up from the factory to only be able to transmit on approved Ham frequencies, but with a little research, it can be turned into a true "all in one radio." If one was to do that, the only thing that the radio is lacking is one lower power setting--current low power is 5w IIRC, and I'd like to be able to transmit on 1w.
Short answer is that there are ways to do what you're after and stay on the good side of the FCC. Commercial manufacturers have in the past and do now sell essentially an open chassis and you put in radios that meet whatever needs you have.I do wish there was a (legal/reliable/quality) option for one radio to operate on CB/GMRS/HAM frequencies.
I understand the way the law is written prevents this, unless they were considered different “radios” packaged in the same “housing”. Antennas would obviously be different as well, I use FRS/GMRS after doing my research which I have no issue with communicating with others in my party. In my neck of the woods though, you’re more likely to hail a stranger in the event of an emergency on CB, but I didn’t want a 4-5’ antenna on my car. A quick connect would be a simple solution when needed.
I’m picturing a CB, GMRS, and HAM “radio” (all sold individually with different model #’s if legally necessary) packaged inside a single housing with one 12v power supply, a 4 way switch to power up the various “radios”, a single mic/handset like the Midland MXT275, and 3 different antenna connections on the housing. Any reason this wouldn’t be possible/kosher?
The basic premise Motorola and Kenwood currently use is you have a front panel used to control multiple RF decks. The RF deck is the radio as far as the FCC is concerned.
Bear in mind that these radios cost several thousand dollars to assemble for one band so the economic justification is going to be tenuous even for ham radio. Having perhaps 3 RF decks and a control face would be tremendously expensive. I think like $5k sort of painful. I just doubt anyone is going to be willing to spend more than $100 for a CB radio or even an FRS or GMRS.