GMRS Frequencies in general

[WSGL775]

I'm new to understanding radio frequencies, specifically programming certain frequencies into the radio. I understand UHF and VHF and the frequency ranges that encompasses each. However, where I get confused is this specifically:

GMRS 1 - 462.562MHz

GMRS 2 - 462.587MHz

In between those two frequencies, is there room to program a frequency such as 462.750? I don't understand the theory behind why there is a large gap between frequencies. Could someone elaborate on this so I'll understand? I just got my license and don't want to make foolish mistakes and lose it!

Many Thanks in advance!

[WRUU653]

GMRS-16- 462.575 sits there already. 

 

[SteveShannon]

12 minutes ago, WSGL775 said:

I'm new to understanding radio frequencies, specifically programming certain frequencies into the radio. I understand UHF and VHF and the frequency ranges that encompasses each. However, where I get confused is this specifically:

GMRS 1 - 462.562MHz

GMRS 2 - 462.587MHz

In between those two frequencies, is there room to program a frequency such as 462.750? I don't understand the theory behind why there is a large gap between frequencies. Could someone elaborate on this so I'll understand? I just got my license and don't want to make foolish mistakes and lose it!

Many Thanks in advance!

Hi John,

For GMRS and FRS, the FCC has designated 22 specific frequencies for our simplex use and 8 more for transmitting to the repeater. 
The channels are interlaced. So tuning to an “in-between” frequency might be interfering with other services or other channels. 
You’ll definitely want to read the regulations to see what frequencies we are allowed and the power and bandwidth:

§ 95.1763 GMRS channels.

The GMRS is allotted 30 channels—16 main channels and 14 interstitial channels. GMRS stations may transmit on any of the channels as indicated below.

(a) 462 MHz main channels. Only mobile, hand-held portable, repeater, base and fixed stations may transmit on these 8 channels. The channel center frequencies are: 462.5500, 462.5750, 462.6000, 462.6250, 462.6500, 462.6750, 462.7000, and 462.7250 MHz.

(b) 462 MHz interstitial channels. Only mobile, hand-held portable and base stations may transmit on these 7 channels. The channel center frequencies are: 462.5625, 462.5875, 462.6125, 462.6375, 462.6625, 462.6875, and 462.7125 MHz.

(c) 467 MHz main channels. Only mobile, hand-held portable, control and fixed stations may transmit on these 8 channels. Mobile, hand-held portable and control stations may transmit on these channels only when communicating through a repeater station or making brief test transmissions in accordance with § 95.319(c). The channel center frequencies are: 467.5500, 467.5750, 467.6000, 467.6250, 467.6500, 467.6750, 467.7000, and 467.7250 MHz.

(d) 467 MHz interstitial channels. Only hand-held portable units may transmit on these 7 channels. The channel center frequencies are: 467.5625, 467.5875, 467.6125, 467.6375, 467.6625, 467.6875, and 467.7125 MHz.

[UncleYoda]

On GMRS certified radios the channels [1-30] are already programmed. Channels 1-14 should have 4 digits after the decimal like 462.5625. These all end in 5 - they're 12.5KHz above and below the frequencies for channels 15-30. If you do a search you should be able to find a chart to help you visualize the relationship.

 

[WSGL775]

Thanks for the explanation! I wasn't sure if you could just use in between frequencies. Now I understand that it could disrupt others services that share the frequencies. Don't want to do that on any frequency!

You know, I did read § 95.1763 GMRS channels and it just went right over my head since the radio already had them programmed in there. I'll admit, I was in a hurry and not paying attention. But again, I appreciate the responses!

 

[WRYZ926]

Here is a full list of all the FRS/GMRS channels.

https://www.buytwowayradios.com/blog/2022/11/list-of-gmrs-frequencies-and-channels.html?srsltid=AfmBOopMy04seYsWSiiA4DFSusU7BoworzqVnVNJg83cZ5PuwO9Wl5V7

[AdmiralCochrane]

[H8SPVMT]

My ole eyes and brain just did not compute this knowledge until, NOW!  Thanks to all that asked and to those that answered!

I kept seeing the words "Mobile GMRS" and thinking my MXT-400 qualified for that.  But then comes along...

"467 MHz interstitial channels. Only hand-held portable units may transmit on these 7 channels. The channel center frequencies are: 467.5625, 467.5875, 467.6125, 467.6375, 467.6625, 467.6875, and 467.7125 MHz.

So now I realize why I don't have those channels in my radio!  We had this exact problem on the trails (Trail Guild wanted to use CH 10.....) now it sinks in after studying this, again Thank you all~!

Edited 19 hours ago by H8SPVMT
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[WRTC928]

2 hours ago, H8SPVMT said:

"467 MHz interstitial channels. Only hand-held portable units may transmit on these 7 channels.

That's why I have those channels set to not transmit on my mobile units. They're there, and if I have a good enough reason, I can fairly quickly turn the transmit feature back on. Having them in the radio means I can listen and even scan them if I want. So far, I haven't felt the need to do that, but it's an option.

[WRYS709]

6 hours ago, WRTC928 said:

That's why I have those channels set to not transmit on my mobile units. They're there, and if I have a good enough reason, I can fairly quickly turn the transmit feature back on. Having them in the radio means I can listen and even scan them if I want. So far, I haven't felt the need to do that, but it's an option.

Which mobile do you use?

[MarkInTampa]

On 1/7/2025 at 8:31 PM, AdmiralCochrane said:

I'm stealing this chart. It's the first time I've seen the frequencies laid out this way, pretty cool.

[nokones]

On 1/7/2025 at 6:31 PM, AdmiralCochrane said:

99

This chart is inaccurate and is mostly confusing and contrary to the rules in Parts 95.567 and 95.1767 in respect to RF output power levels for both the FRS and GMRS radio services. The rules state that Channels 1-7 are regulated to 2 watts ERP for non-licensed FRS service and 5 watts ERP for licensed GMRS service. The left chart indicates channels 1-7 for both FRS & GMRS are regulated to a .5 watt and that is incorrect.  The right chart indicates that Channels 8-14 are regulated to .5 watt ERP for FRS and that is correct, and 5 watts for GMRS and that is incorrect, all transmitter transmitting on these channels are regulated to a .5 watt ERP, regardless of the two radio services. 

The left chart indicates that channels 15-22 are regulated to 2 watts ERP and that is correct.

Both charts indicates that the 462 (462.550, 462.575, 462.600, 462.625, 462.650, 462.675, 462.700, and 462.725) and 467 (467.550, 467.575, 467.600, 467.625, 467.650, 467.675, 467.700, and 467.725) Main Channels are regulated to 50 watts and that is correct, except for the 467 main channels, they are regulated to 15 watts for fixed class station operations.

The 50-watt output is not limited to the measurement of antenna ERP for the 462 & 467 main channels. The 50-watt output limit is the measurement of power out of the transmitter before the antenna and there is no limit of the ERP of the antenna.

[Lscott]

FRS-GMRS Channels Layout.pdf

[MarkInTampa]

6 hours ago, nokones said:

This chart is inaccurate and is mostly confusing and contrary to the rules in Parts 95.567 and 95.1767 in respect to RF output power levels for both the FRS and GMRS radio services. The rules state that Channels 1-7 are regulated to 2 watts ERP for non-licensed FRS service and 5 watts ERP for licensed GMRS service. The left chart indicates channels 1-7 for both FRS & GMRS are regulated to a .5 watt and that is incorrect.  The right chart indicates that Channels 8-14 are regulated to .5 watt ERP for FRS and that is correct, and 5 watts for GMRS and that is incorrect, all transmitter transmitting on these channels are regulated to a .5 watt ERP, regardless of the two radio services. 

The left chart indicates that channels 15-22 are regulated to 2 watts ERP and that is correct.

Both charts indicates that the 462 (462.550, 462.575, 462.600, 462.625, 462.650, 462.675, 462.700, and 462.725) and 467 (467.550, 467.575, 467.600, 467.625, 467.650, 467.675, 467.700, and 467.725) Main Channels are regulated to 50 watts and that is correct, except for the 467 main channels, they are regulated to 15 watts for fixed class station operations.

The 50-watt output is not limited to the measurement of antenna ERP for the 462 & 467 main channels. The 50-watt output limit is the measurement of power out of the transmitter before the antenna and there is no limit of the ERP of the antenna.

I like the chart for how is visually displays the channels and frequencies, didn't even look (or care) about the power limit thing. I've got a similar chart for shipboard communications in kind of the same format, it's just the first one I've seen for GMRS.

 

[WSGL775]

What a wealth of information this has become for me in understanding how things work and what is authorized in accordance § 95.1763 GMRS channels. Sometimes you have to slow down to speed up, if that makes any sense to you. Thank you, all of you for this help!