The Model 550 Linear Signal Summer hosts seven inputs and allows the user to select up to four to be summed in the composite output. ON/OFF and signal level control is provided for each of the four selected signals. The signal level of each selected input can be varied from +3 dBm to -30 dBm (50 Ohm load), in 0.1 dBm increments. The composite output provides unity gain. 

Signal selection, level control and On/Off are software selectable via the front panel or remote control bus. The Model 550 is a 3.5” chassis supplied with non-tilt slides.