Users should be aware that this switch as it comes from the manufacturer does
not GROUND unselected antennas. Nor does it GROUND antenna ports when it is
powered down. You must open the relay case and carry out a modification as
instructed in the operators manual. The mod involves soldering a short jumper
from the center pin of the UHF connectors to a pad on the circuit board. This
pad is the mounting point for one terminal of the changeover relay for each
antenna port and provides a ground connection when the port is NOT selected and
also when the power to the relay head is turned off.
I recently acquired one of these switches from an estate sale and noted that the
operator had not carried out this mod. He had been using the unit for a number
of years with multiple coax runs that were "floating".