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Why the value of intermediate frequency (IF) of amplitude modulation (AM) is 455 kHz? Why not another value?

Wei-Cheng Liu
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  • What makes you think it is? – Phil Frost - W8II Nov 26 '14 at 12:12
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    Related: http://ham.stackexchange.com/questions/850/how-is-the-if-for-a-superhet-selected – VU2NHW Nov 26 '14 at 12:28
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    It was developed over time for the "Broadcast Band" as a compromise between "Image Rejection" and "Selected Bandwidth". A low "IF" would have narrow bandwidth but poor Image rejection and visa versa. Some receivers designed to work well above the "Broadcast Band" use a "Higher IF" for image rejection, and a "Lower IF" to control the bandwidth skirts. I once had a very old BCB receiver that used 265kc for its IF. – Optionparty Nov 26 '14 at 13:34
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    @Optionparty You should post that as an answer. – Kevin Reid AG6YO Nov 26 '14 at 17:41
  • I think a good answer is the referenced question posted by @VU2NHW. Actually, the IF for AM has been various frequencies in the 4xx kHz range. – K7PEH Nov 27 '14 at 02:48
  • voting to close because 1) the question is based on a false premise with no source cited, and 2) How is the IF for a superhet selected? is the answer to this question without the false premise. – Phil Frost - W8II Nov 27 '14 at 17:59

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