THIS is why you need to take my class.
In theory a repeaters range is almost limitless. Radio waves go into space forever. In June and July when the tropospheric ducting is just right, sometimes you can stand on the beach at Huntington and work the repeater in Honolulu with a five watt hand held. I can hit the Mt. Potosi 220 machine above Las Vegas from Wrightwood.
In practicality a repeaters range is limited more by the radio you are using than by the repeater. Repeaters are frequently 100 watt radios and are on very high mountain tops. Your mobile or HT is 5 to 50 watts and blocked terrain, buildings, and vehicles.
The other limiting factor is terrain. VHF radio waves do not go through or over mountains.
If you take a map of southern California and draw a triangle from
Azusa, to Huntington Beach, to Manhattan Beach, that is roughly the coverage of TMO. Yorba Linda is not in the triangle but close.
The problem with Yorba Linda is that it sits tucked up behind the south side of the Chino Hills so it's a tough shot for Keller or TMO.
Linked repeaters solve this problem. There are none on 2 meters that will get you from Yorba Linda into Wrightwood.
