General Mobile Radio Service (GMRS)

Created Monday 26 December 2022

The General Mobile Radio Service (GMRS) is overall the most capable of the personal radio services. A license is required for legal operation. The license costs $35.

Some combination FRS/GMRS radios exist which may also have FRS channels 8-14. Such radios will be constrained to using a built-in antenna and will only transmit with 500 mW on those 7 channels.

Advantages:

Wide range of radio types available (Mobile, base, handheld)
Repeaters are permitted
High power limit on some channels
No limit on antenna gain
Can interoperate with FRS on some frequencies.
Generally supports CTCSS and sometimes DCS to keep radios quiet when other groups may be using the channel

Disadvantages:

Range may be especially limited in wooded areas due to UHF not passing through foliage easily.
License required
Radios may be expensive at times.

Mode: FM*

*Technically many others are legal, but only FM is common.

Antenna dimensions:

Wavelength: 65cm
Quarter wave: 6"
Five eighths wave: 16"

Power:

Main channels: 50 W
Repeater inputs: 50 W
Interstitials: 5 W

RF Bandwidth: 25 kHz

Available channels:

Simplex: 15
Repeater: 8 pairs

Frequency listing (MHz):

Main group  Repeater input
462.5500    467.5500
462.5750    467.5750
462.6000    467.6000
462.6250    467.6250
462.6500    467.6500
462.6750    467.6750
462.7000    467.7000
462.7250    467.7250

Main group may be used for simplex communications. Repeater inputs are for repeater operation only, with the repeater output being on the main group channel that is 5 MHz below it. The main group can be used to interoperate with FRS on channels 15-22.

Interstitial
462.5625
462.5875
462.6125
462.6375
462.6625
462.6875
462.7125

Interstitial channels are for simplex communications only. They can be used to interoperate with FRS on channels 1-7.

Backlinks: Communications:Two-Way Radio:Personal Radio Services