A television (TV) receiving system includes a first TV receiver for receiving TV signals in a first range of frequencies, such as are used for cable, VHF and UHF broadcasting including a frequency synthesizer type local oscillator. The frequency synthesizer uses a voltage controlled oscillator (VCO) controlled by a tuning voltage responsive to a first frequency feedback signal. The receiver includes a coupling arrangement for adapting the receiving system for use with an external plug-in unit including a second TV receiver for receiving TV signals in a second range of frequencies, such as are used for direct broadcast satellite (DBS) signals. The second TV receiver provides a second frequency feedback signal. The receiving system includes a multiplexer for selectively coupling one of the first and second frequency feedback signals to the frequency synthesizer for controlling the VCO.