Mark,
I googled for MC60 manual and extracted the portion you need. See below.
Pat, K9JAU
Microphone Preamplifier
You can use this microphone with any KENWOOD transceiver. It has been
designed especially for FM and SSB mobile transceivers. You can
control the preamplifier
using the MIC AMP IN/OUT switch on the inside of the base of the transceiver.
First renove the base of the microphone, then slide the switch to the
IN position to turn the preamplifier ON. With the switch in the OUT
position, the preamplifier is bypassed and the batteries are
disconnected. To conserve battery power, turn the preamplifier OFF
when it is not in use.