Originally Posted by DaveInDenver
This is the legal part I don't understand. If you read Part 95, Subpart E about the specifications for CB, it seems like any ham radio would have no trouble meeting the requirements. The bandwidth, sporadic and radiated emissions, sensitivity, etc. for CB is far less restrictive than what's possible with our ham radios. Ham radio is covered by the Part 97 requirements and since hams are expected to tinker, the actual technical requirements for ham are different. It's perfectly legal for you to modify and build your own gear for ham. You can take a CB radio, modify it for use on 11m and there's nothing wrong with doing that, perfectly within your realm as a ham. But I think once you do that, the radio is no longer technically legal to use on CB. So I guess my comments are only talking out loud, since ham rigs are not tested to Part 95. It seems the radios themselves should more than meet the technical requirements laid out (and naturally it would be up to the operator to make sure to use the proper transmitter power for CB). It's all moot because it's not legal to use it.
I kinda preached this in the Ham class I did for the club last fall. You're correct, as a ham, part of the hobby is to tinker. So could someone get all funky and build a radio with two different VFO's in one box, one for CB and the other for VHF, sure! Would the FCC question a radio at 4 watts PEP that is transmitting on the CB frequencies, probably not in a hundred years. Bruce(WØDW) made reference at the ham class to actually using a modified CB rig on 10 meters and it worked well using 3 watts of power. Correct again, according to part 95, it would no longer be a "type-accepted" CB radio. Is someone somewhere using a ham radio for both CB and VHF? Probably. Can anyone just go down to Radio Shack or HRO and buy a radio that does this? No.
Folks who are not in "the know" think that CB and VHF are relatively the same thing because the antennas are realtively the same height, and the radios are in a similar case. What remains a mystery is that to have that CB radio work at the same level as a 5 watt VHF rig you would need a much larger, much more effecient antenna than what is commercially available not to mention not as pratical to mount on a bumper.
The channels up to (IIRC) 23 use dual sideband AM. After that, 24 thru 40 MAY use single sideband (SSB) but most radios use AM for the entire band. VHF and UHF more commonly operate on FM, but some folks also use SSB. When used efficiently, AM gives a much richer, full signal partly because you are using the entire carrier to transmit the signal. SSB uses only half that carrier, so the same power carries further.