Sorry guys...below is the message copied and pasted from Alpha!!! We use an IC-746 for daily testing of 99 amps (same specs as the 91B). It has been in use for over 2 years and we have not had a failure of the amplifier keying circuit in the radio. I don't have any info on the 756 radios, however. Have a great day, because if you don't someone else will!!! 73, Steve, NX1G