You just now finding all this out? The NARBA treaty in March 1941 was what changed frequencies of AM stations all over the country. Before that, KYA was on 1230, KLS (I think) was on 590 before moving to 1310, KQW moved to 740, leaving 1010 vacant for 17 years, KWG was at 1200, then took KYA's place at 1230, In LA, KHJ went to 930 from 900, KECA would've gone to 1460 from 1430 except Anthony sold it 'n' bought 780, I believe. In Sacramento, KFBK went to 1530 from 1490, KROY moved to 1240 from 1210, and the list goes on and on. In the Bay Area, KPO, KSFO, and KFRC stayed put thru the NARBA switch.