The Tehachapi area is somewhat different than Donner Pass, in that the railrroad is shared by Union Pacific and Burlington Northern Santa Fe, and that makes for some great railfanning.  The following frequencies work for me when I am railfanning the Tehachapi Pass and Mojave area:  The Tehachapi Line, that runs from Bakersfield to Mojave, in central California, is the busiest single-tracked mainline on the North American Continent, and sees usually around 50 trains a day.  Plug these frequencies into your scanner, and enjoy some outstanding railfanning!

160.320 - U.P. dispatcher 54, Bakersfield to Mojave

161.085 - B.N.S.F. dispatcher, secondary frequency, Bakersfield to Mojave

160.890 - U.P. PBX, Pampa Peak repeater

160.950 - U.P. PBX, Oak Creek Pass repeater

160.260 - B.N.S.F. PBX, Oak Creek Pass repeater

160.335 - B.N.S.F. PBX, Bena Mountain repeater

160.425 - B.N.S.F. PBX, Oak Creek Pass repeater

161.430 - U.P Bakersfield yard frequency

161.370 - B.N.S.F.  Bakersfield yard frequency

Go ahead, program those frequencies into your scanner and you'll hear all of the action on this busy piece of railroad line.