The Apex DT-250 CECB has a flaw that will cause it to go to NO SIGNAL when there is a signal still present. the flaw is in the back of the box, the ANT IN port has nothing to keep it from being moved around if one's connecting the cables up and can literally become disconnected from the tuner inside if one disconnects or reconnects often enough. what needs to be done is use a small nut that you can get from a satellite/cable supplier that they use to hold the faceplate to the cable ports in a home. it goes around any standard RG coax screw-on type port and can be used to make the Apex ports more strong and keep them from breaking off inside the box.
My Apex suffered that malady and required a day with a soldering iron to reconnect the tuner to the port inside and then a nut used to keep it held to the box and not break loose. just thought i'd pass it along.