KCET-TV Channel 28 was knocked off the air from 10:50 a.m. to 12:35 p.m. Wednesday when strong winds damaged the public-TV station's Mt. Wilson transmitter. The winds--reported gusting 60-70 m.p.h. in some foothill communities--caused numerous television and cable reception troubles in Southern California. KTBN-TV Channel 40, KVEA-TV Channel 52 and KLCS-TV Channel 58 were also forced off the air for short periods due to interruptions in power supply. Century Cable customers in the San Fernando Valley and West Hollywood reported reception problems on pay-cable channels.