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.

GMRS radios can interoperate with FRS radios, however, not all radios are capable of operating on all channels due to legal limitations.

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
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 TPO
Repeater inputs: 50 W TPO
Lower Interstitials: 5 W ERP
Upper interstitials: 500 mW ERP

RF Bandwidth:

Channels 8-14: 12.5 kHz
All other channels: 25 kHz

Available channels:

Simplex: 22
Repeater: 8 pairs (overlapped with simplex)

Frequency listing (MHz): 

	**Lower interstitial channels**
		Radio types:  Mobile, Base, Handheld
		Maximum power:  5 W ERP
		Bandwidth:  25 kHz

Channel Frequency
 1      462.5625
 2      462.5875
 3      462.6125
 4      462.6375
 5      462.6625
 6      462.6875
 7      462.7125

	**Upper interstitial channels**
		Radio types:  Handheld
		Maximum power:  500 mW ERP
		Bandwidth:  12.5 kHz

Channel Frequency
 8      467.5625
 9      467.5875
10      467.6125
11      467.6375
12      467.6625
13      467.6875
14      467.7125

	**Main group**
		Radio types:  Mobile, Base, Handheld, Repeater
		Maximum power:  50 W TPO
		Bandwidth:  25 kHz

Channel Simplex Frequency Repeater input
15      462.5500          467.5500
16      462.5750          467.5750
17      462.6000          467.6000
18      462.6250          467.6250
19      462.6500          467.6500
20      462.6750          467.6750
21      462.7000          467.7000
22      462.7250          467.7250

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