[RFI] Switching power supply rfi

[wb4mle at surfbest.net]

I have an 18 amp Tamura and a 25 amp Radioshack 22-510 switchers that
both seem to radiate a drifty square wave about every 45 to 90 khz up
thru 5 MHZ or so. The radiation seems to be getting on the house
wiring via the power cord. Tried a plug in filter (UPS) with no help.
Any ideas to reduce this rfi or sites to research so I can retire my
Motorola HPN1003A analog supplies? Thanks de Eddie, WB4MLE