What device converts the RF input and output of a transceiver to another band?

The device that converts the RF input and output of a transceiver to another band is a transverter. A transverter takes signals from a transceiver operating at one frequency (or band) and converts them to a different frequency (or band) for transmission or reception. This is especially useful in amateur radio, where operators may wish to access bands that their current transceiver does not support directly.

Transverters typically operate by mixing the incoming RF signal with a local oscillator frequency, effectively shifting the signal to the desired band. This allows for the expansion of available frequencies for communication without needing separate transceivers for each band.

Other choices like high-pass filters and low-pass filters are designed for frequency selection but do not convert frequencies between different bands. Instead, they allow signals of certain frequencies to pass while attenuating others. A phase converter primarily deals with changing the phase of signals, which is not relevant to frequency conversion in the context of radio communication. Hence, the transverter is the appropriate answer for its function in enabling operations across varying amateur radio bands.