A few years back I bought a couple of Kenwood PMR's off ebay. They worked well, and I was pleased with them, until I tried to use them with other PMR radios...
Turns out they didn't have the right coding or some such, and while I could hear PMR radios, they couldn't hear me. Don't think it's something you are going to come across, but thought I'd mention it incase you get tempted by something on ebay...
J
The Kenwoods you have could in all likelihood be programmed (with the same programming cable and free software mentioned in this thread) to be bang on the PMR channels and correct CTCSS codes. If you could hear others, but they couldn't hear you, the chances are that you were just transmitting on one of the 8 main channels with no CTCSS code, but they had CTCSS coding switched on. Either that or your TX (transmit) and RX (receive) channels were programmed on different frequencies/CTCSS codes. Don't bin the radios! 20 minutes with a £3 cable will sort them....