I have a 148 gtl.. when you tx, there is a loud high pitched tone at the receiving end(receiving radio)...and it is garbled...tried switching radios and when I tx the 148, the other radio had the same high tone, garbled rx??

How far away are they? It sounds to me like they are in the same room???

If so, you are getting feed back. CB's are not meant to be that close. As well, the also would raise another issue. Are their antenna's hooked up?

CB radio's need a CB antenna or you can damage the radios. The radio energy will not leave the radio and burn up the transmit section of the radio.

the both need an antenna, and the antenna needs to be tuned.

Also, if you are operating them close like that, you can also damage the receive on the radios.

also, when 2 radios are too close, it over loads the receive circuits on the radio ant thats why its garbled.