Joe, A longer wavelength could certainly be being radiated - for example the power supply diodes are a possibility even if there is minimal electronics elsewhere. Also, the radiation may not be from the oven itself, it may be injecting signal into the AC wiring & radiating from there There's also a possibility that any built-in filter has become bad over time - or, more likely, nothing much was fitted in the first place. Have you gat a suitable AC filter you can place close to the oven? RP On 13 October 2010 09:39, ivp wrote: >> Joe (OP), have you tried holding that metal shielding plate at various >> distances from the microwave but along the =A0line of sight? It would be >> interesting to see if it still prevents the interference when you are >> holding it near the microwave oven instead of near the set-top box > > Surrounding the microwave oven with several cooking trays (~1mm > thick, 12" x 16") is much less effective than one tray in front of the se= t- > top box > > AIUI, the microwave oven enclosure is supposed to be a Faraday > cage at microwave frequencies, for the obvious reason. So what is > being radiated could be longer wavelength RF ? > > * > * > ********** > Quality PIC programmers > http://www.embedinc.com/products/index.htm > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .