I recall reading that if an AM radio is tuned to frequency x plus or minus the heterodyne frequency a radio tuned to frequency x will be blotted out. Is this true? If so what is the heterodyne frequency? Will it work with FM?

Reply to
Roger Dewhurst
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The local oscillator (L.O.) in an AM band set is 455KHz away from the carrier - usually higher.

The IF for FM is (or was, lo these many years ago) 10.7 MHz, and the L.O. is usually higher.

Yes, if you have a really crappily-designed AM receiver, tuning it to a freq. 455KHz below the carrier of the station in question can interfere with its reception. But they _should_ be designed to not emit any L.O. signal, for this very reason.

On FM, not so much, if at all, because of the different characteristics of the modulation/demodulation technology.

Hope This Helps! Rich

Reply to
Rich Grise

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