I have an ICOM-7100 that I've installed in my mobile as my primary (nay, only) HAM transceiver; and I'm trying to avoid wasting a ton of space in my vehicle (not to mention money) for a proper scanner, or for a CB¹, to achieve fuller coverage of the available spectrum-space. Unfortunately, some poking around frequency-listing websites reveals that a lot of the interesting non-HAM action happens over “NFM” — which I finally ascertained² to be a 2.5kHz-deviation FM mode used by commercial / emergency-services devices.

I'd really like to scan across such channels without installing yet-more equipment in my passenger compartment; and yet I can't find any mention whatsoever of FM deviation in my ICOM-7100 manual. Is there any way for me to intelligibly receive (or for that matter, transmit) 2.5kHz-deviation FM signals with my transceiver?

¹ Not very related, but to my annoyance, it looks like there's no MARS/CAP modification for the 7100 that covers the CB “11-meter band”, 26.965–27.405MHz. I might have to install a second damn box to talk to truckers. Bah.

² It also looks like a huge set of the interesting frequencies are digital “Project 25,” P25, mode; I'm just assuming there's no hope of receiving those on a HAM transceiver. :P

  • $\begingroup$ This site is all about creating a database of questions with answers. Please don't combine questions, because that breaks the way the site works. Your other questions should be asked separately, if they haven't been asked already. $\endgroup$
    – rclocher3
    Nov 9, 2016 at 20:45
  • $\begingroup$ Those weren't really questions (I wouldn't ask for CAP mods on a stack-exchange!), just conversational comments. (I participate heavily on various SEs and SO; but if such a conversational style of question is unwelcome on this particular site, I'll try and moderate my approach!) $\endgroup$ Nov 9, 2016 at 20:46
  • $\begingroup$ Here's a similar question to your question about CB. Regarding P25, hams do have P25 repeaters set up, but I believe they use repurposed commercial radios to do so. I'm not sure if there is such a thing as a scanner that can receive P25. $\endgroup$
    – rclocher3
    Nov 9, 2016 at 20:50
  • $\begingroup$ There are a lot of sites telling how to do the MARS mods on the 7100: google.com/search?q=ICOM-7100+mods $\endgroup$
    – SDsolar
    May 15, 2017 at 1:32

1 Answer 1


Regarding your original question, according to page 5-6 of the IC-7100 Advanced Instructions document, to receive "narrow" FM of 2.5 kHz deviation, select FILTER2 or FILTER3.

  • $\begingroup$ Ahhah! I was mis-led by the “Passband widths for FM … are fixed, and cannot be set!” Well-spotted, my man. $\endgroup$ Nov 9, 2016 at 20:43

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