Every time I key the mic the radio screams like feedback and no keyup on the bands

SOURCE: Lost channels in a galaxy 66v cb radio

as far as the transmit frequency changing while you have the mic keyed this is normal, the transmit frequency is a little different than the receive, as far as the lost channels go you need to check the galaxy website and check to see if thier is any fixes listed. if none is listed then you can send the tech's a e-mail and tell them your problem and they will advise you on what to do.

SOURCE: no cb channels no audio no recive

If you have no channel display or CB operation, it sounds like a blown voltage regulator that supplies power to the CB PLL circuit.

SOURCE: When mic is keyed, TX light illuminates but power meter does not

make sure your s/rf switch is in the right place on the radio is the most common problem i have found

SOURCE: cobra gtl 148 seems to have no power til i push on mic connecter.

cobra 148 shows no wattage output on external meter but does show good modulation.

SOURCE: Radio squeal.

Check it with the external speaker unpluged, turn the mike gain down a little at a time, until it does not squeel. ..hope this helps..