Typically, in early evening, we have three simultaneous AM QSOs on 3885, 3880 and 3873; sometimes with one or more of these QSOs operating as a "net". Five kc/s is too close for two adjacent AM signals. There is nothing sacred about those frequencies, and few of the stations crystal controlled. Wouldn't it make more sense to transmit on 3879, rather than insisting on 3880? 3879 falls precisely at the midpoint between the other two AM QSOs, leaving 6 kc/s separation between each signal, and less mutual QRM.