ATU Receive Only

I like to monitor a range of digital frequencies with the 6700. Have found that activating the ATU on a low band usually de-sensitizes the higher frequencies. This happens even when using two antennas on the 6700. IE 6M slices on a 6M antenna and the HF bands on a HF antenna. If activating the ATU on a HF band the 6M side goes dead. Would like the ATU to be connected in the antenna circuit only when transmitting. I realize this may be a problem for CW and QSK but for all other modes [switching the ATU in and out between transmit and receive] seems possible.