The Contemporary Research QDA4-45 is an amplified RF combiner that can switch between one or four inputs, with adjustable amplification up to 50 dB. </p><p>Designed for QMOD HDTV applications, the QDA4-45 can receive an RF feed from QMOD modulators or QCA9-33 Active Combiners. Inputs can be switched between one or four inputs, with selectable gain. <br /> <br />The compact QDA4-45 mounts two across in a single rack space using CR RK1 and RK2 rack kits, and can be mixed with QMOD HDTV modulators using the same rack kits. The units are wholly designed and manufactured in the USA.</p><p>This unit includes a universal rack mount kit, which is a combination of the RK1 & RK2EZ that will allow you to mount the unit into a 1RU or 2RU slot in your Rack right out of the box.</p>