Which pair shares the whip antenna through the diplexer?

• A. VU1 and FM1
• B. VU1 and FM2
• C. FM1 and FM2
• D. VU2 and FM2

Answer: (A)

A diplexer lets two radios on different frequency bands share one whip antenna by keeping their signals in separate paths. In a typical setup, one input port of the diplexer is fed by a VU transmitter and the other input port is fed by an FM transmitter, with the whip connected to the diplexer’s common antenna port. This arrangement lets both transmitters access the same antenna without interfering with each other, because each signal is confined to its own band by the diplexer. FM units on the same band wouldn’t use the diplexer to share the antenna, and pairing two FM units or two VU units wouldn’t involve the two distinct input ports of the diplexer that are designed for different bands. So the pair that uses the diplexer to share the whip antenna is VU1 and FM1.