220 MHz amateur radio boasts of a long and colorful history, affording it a special place in the hearts of amateur radio enthusiasts. 

Conceptually, amateur radio repeaters are not too different from public safety devices (fire, first response, police) or those in use at federal, business or military services. However, they are often assembled (power supplies, transmitter, receivers, antenna etc.) or commercially packaged to operate only within amateur RF (radio frequency) bands, like 222-224.995 220 MHz band.

History

The Federal Communications Commission (FCC) approved VHF bands as early as 1938, one of them being 1.25 meters (224 MHz) band. Amateur radio activity spiked rapidly in 1960s and 1970s, as 2m and 70cm bands swiftly rose to prominence in the hobby. The commercial spectrum of the VHF and UHF bands became the backbone of emergency service communications like police, fire and ems. The 1.25m band however, escaped the commercial popularity - partly due to lack of enough commercial frequency allocations. Add to it, commercial radio equipment for the band has been scarce. Amateurs willing to go live on this band have had to build their own equipment or buy specialized amateur radio equipment from designated manufacturers.

Duplexers and Repeaters Some Basic Information BY ROBERT A. LEHNING*, WA2YSJ All across the country there are many amateur repeate  stations operating on 2 meters, 220  and 440 MHz, and to some extent on 1.2 GHz.  Several  modes of operating such as FM, ATV, and packet (digital) have also become...