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  • Why mobile GMRS radios don't transmit on channels 8-14

    GMRS Handheld and Mobile ChannelsMobile GMRS radios have become increasingly popular during the last few years. The concept of a mobile or base station radio that operates on the GMRS and is fully compatible with a traditional handheld GMRS transceiver is of great interest to many licensed GMRS operators. Considering that the General Mobile Radio Service includes 22 standard simplex channels, it is naturally assumed that a GMRS mobile will transmit on them all, just like a portable handheld model. But that isn't the case. Why?

    Our customers ask us why their mobile GMRS radio cannot access channels 8-14, or can only receive on them. For instance, the Wouxun KG-1000G can receive on those channels, but cannot transmit on them. In the case of Midland's MicroMobiles, channels 8-14 are missing entirely. It isn't just a FAQ from our customers. This is also an item of speculation on GMRS forums and in the comments section of many Youtube videos.

    So, what gives? Why are these channels fully accessible on a portable handheld GMRS walkie talkie, but not available for transmit on Part 95 type accepted, FCC approved GMRS mobile or base station radios?

    The popular answer provided in these venues commonly focuses on the wattage limitation imposed by the FCC on these channels. The typical line of reasoning is that these channels have a one half watt transmit limit, and high powered mobile radios simply can't reduce their power to such a low level, so therefore they can't transmit on those channels legally. While the wattage theory does make some sense, and the inability to go below one watt may indeed be the case with some mobile radios, this answer is not actually correct.

    The real reason can be easily found within the FCC rules for GMRS. Specifically, the rule in Part 95, Subpart E which limits the frequencies commonly assigned to channels 8-14 to hand-held radios only. Here is the applicable section (from § 95.1763 GMRS channels):

    (d) 467 MHz interstitial channels. Only hand-held portable units may transmit on these 7 channels. The channel center frequencies are: 467.5675, 467.5875, 467.6125, 467.6375, 467.6625, 467.6875, and 467.7125 MHz.

    Those channel center frequencies are the seven frequencies assigned to GMRS channels 8-14.

    In other words, only handheld GMRS radios can transmit on channels 8-14 because, well, you can only transmit on channels 8-14 with a handheld GMRS radio.

    Yep, because the FCC said so. That's all it is. And there you go.

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