when using 2 hb units.,I read an article that said to reduce interference,when using dual beam transducers,is to put 1 unit on 200 khz and the second unit on 83 kHz.My question is ,on the HB 798 ,when you turn off the 83 or 200.,does the HB turn off the transmitter or receiver.ie: does the unit keep transmitting and just not process the the returns?