1) Remove all the power to the modulator when connecting or removing cables.
2) Connect a HDMI cable from the DVR / NVR (or other video equipment) to the HD IN of the MOD300.
3) When combining the RF signal of a TV aerial and the MOD300, connect the TV aerial coax (f-connector) to the RF.IN port.
4) Connect a coax (f-connector) to the RF.OUT port direct to a TVs aerial socket or to a distributor to multiple TVs.
5) Connect the 12V DC power supply to the MOD300, then re-tune the TVs.