Welcome Forums Newcomer Help & Advice Help with FM vs FM-N

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    • #1678

        I recently got my Foundation licence, and bought an Icom ID-52E to get on the air. The radio has both an FM mode and an FM-N mode, and I’m trying to understand when you would use each.

        According to the specs, FM mode uses a maximum 5kHz deviation, and FM-N uses a maximum 2.5kHz deviation. I’ve done some research and found the Carson bandwidth rule, which I think means the approximate bandwidth for FM would be 16kHz, and for FM-N it would be 11kHz.

        Looking at the band plans, for the 2m band the FM simplex channels have a 12.5kHz spacing, so I’m assuming FM-N needs to be used here. For the 70cm band, there’s a note that the recommended bandwidths are 12.5kHz or 20kHz, which suggests you could use either. For repeaters, the band plans say 12.5kHz channels at 2m, and 25kHz for 70cm, so I’d have thought that I should be using FM-N for 2m repeaters, and FM for 70cm repeaters.

        Where I’m confused is that Icom provide a list of repeater memories for the radio, and those memories are set to FM mode for all repeaters across both bands.

        Am I misunderstanding something, or are the repeater memories from Icom incorrect, and they should be using FM-N for the 2m repeaters?

      • #1679

          FM tends to used for stand simplex voice,

          FM Narrow tends be be used on repeaters and FM sattelites

          thats my understanding


          M0PWX (not Pete M0PSX who runs the site)

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