What is the purpose of GMRS channels 8-14?

[WRZT691]

Hello, I am a GMRS newbie, only having my license for 6 days. What is the purpose of channels 8-14 being they are only 1/2 watt? Makes no sense to me, seems useless. What kind of range can one even get on 1/2-watt channels? Another question, more out of curiosity, would someone still have to provide their caller ID if they were on those channels?

[WRYC373]

Short answer its to allow full compatibility with frs. Those channels were originally FRS only pre 2017.

Yes if operating a gmrs radio you need to by rule announce the same as any other channel.

 

Those channels if you look at frequencies are close to repeater inputs and the reason why power is low is to prevent any interference on the repeater inputs.

[WRZT691]

Quote

 

Thank you for answering my question, helping a noob. I haven't purchased my radio, still looking to see all the options available on the market. 

[WRYS709]

So the converse: if you are operating an FRS radio on one of those channels, or any other FRS channel, you do not need to ID.

[Lscott]

12 hours ago, WRZT691 said:

What is the purpose of channels 8-14 being they are only 1/2 watt? Makes no sense to me, seems useless.

The FCC screwed up when they allowed the sale of combination FRS/GMRS radios before the rule changes in 2017. The idea was if one wanted to use the GMRS specific, at the time, channels one would have to get a GMRS license. Well, almost nobody bothered. So, when the rules were changed in 2017 the FCC had to do something about all the existing radios out there. They simply changed the rules to make those combination FRS/GMRS radios FRS only and legal to use as is.

However the channels you pointed out sit between the main GMRS repeater input channels, which use a 25KHz channel. The FRS channels, 8-14, where kept at very low power and narrow band since they partially overlap the main GMRS repeater channels. The idea was to minimize the interference they cause. At the time FRS was limited to 0.5 watts and narrow band, 12.5KHz channel, so keeping the restrictions didn't require any changes to existing radios.

As you pointed out for FM use they are basically useless. Many GMRS specific radios don't even include them, noticeably on mobile radios. So practically speaking GMRS really has useful access to only 15 channels. 

You might ask is there something that those channels could be used for? Maybe, but that's a topic for another thread, which if you look you'll find on the forum discussing adding channels to GMRS. 

FRS-GMRS Channels Layout.pdf

[WRXB215]

As far as I can tell, for GMRS, those channels are only useful for radios like the Baofeng MP31 that can transmit at .5 watts on those channels.

RF Output Power ≤2W (1-7&15-22&23-38Channels) /≤0.5W(8-14Channels)

[WRYZ926]

GMRS mobiles radios only go down to 5 watts so they aren't allowed on channels 8-14. That being said, I do know of at least one mobile radio that will transmit on those channels. Not like I would do that though. 

[wrci350]

35 minutes ago, WRYZ926 said:

GMRS mobiles radios only go down to 5 watts so they aren't allowed on channels 8-14. That being said, I do know of at least one mobile radio that will transmit on those channels. Not like I would do that though. 

Type-accepted GMRS mobiles don't transmit on those channels because they aren't allowed to:

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.

Note that it says "hand-help portable" only.  Nothing to do with power limits.  Probably more a case of "mobile GMRS radios don't go down to .5W because there is no point" rather than "can't transmit there because the minimum power is too high".

I'm sure you wouldn't transmit there from a (non type-accepted) mobile, because you dont' want to take a chance of interfering with a repeater on an adjacent frequency.

[WRYZ926]

12 minutes ago, wrci350 said:

Type-accepted GMRS mobiles don't transmit on those channels because they aren't allowed to:

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.

Note that it says "hand-help portable" only.  Nothing to do with power limits.  Probably more a case of "mobile GMRS radios don't go down to .5W because there is no point" rather than "can't transmit there because the minimum power is too high".

I'm sure you wouldn't transmit there from a (non type-accepted) mobile, because you dont' want to take a chance of interfering with a repeater on an adjacent frequency.

The one mobile radio that I know will transmit on channels 8-14 is a type accepted GMRS mobile radio. The Wouxun KG-XS20G definitely will transmit on channels 8-14 if you set them to low power (5 watts) and also set them to narrow band.

[WRYS709]

20 hours ago, WRZT691 said:

What is the purpose of channels 8-14 being they are only 1/2 watt?

Groups and families within a close range of each other use these channels to avoid clutter and interference from others using these Channels.

[nokones]

3 hours ago, wrci350 said:

Type-accepted GMRS mobiles don't transmit on those channels because they aren't allowed to:

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.

Note that it says "hand-help portable" only.  Nothing to do with power limits.  Probably more a case of "mobile GMRS radios don't go down to .5W because there is no point" rather than "can't transmit there because the minimum power is too high".

I'm sure you wouldn't transmit there from a (non type-accepted) mobile, because you dont' want to take a chance of interfering with a repeater on an adjacent frequency.

Pursuant to Section 95.1767.(c) the power on the 467 Interstitial freqs are regulated to half a watt ERP. 

[gortex2]

3 hours ago, WRYZ926 said:

The one mobile radio that I know will transmit on channels 8-14 is a type accepted GMRS mobile radio. The Wouxun KG-XS20G definitely will transmit on channels 8-14 if you set them to low power (5 watts) and also set them to narrow band.

Then they still dont meet the rules....

 

[WRYZ926]

23 minutes ago, gortex2 said:

Then they still dont meet the rules....

 

I never said they did. I just said that the XS20G Plus is capable of transmitting on channels 8-14. Do so  at your own risk.

[Adamdaj]

On 12/17/2023 at 10:00 PM, WRZT691 said:

Hello, I am a GMRS newbie, only having my license for 6 days. What is the purpose of channels 8-14 being they are only 1/2 watt? Makes no sense to me, seems useless. What kind of range can one even get on 1/2-watt channels? Another question, more out of curiosity, would someone still have to provide their caller ID if they were on those channels?

That question of yours about channel 8 through 14 makes sense. I read the FCC Part 95 subpart A, B, & E and I still don't see the reason for half watt on channels 8 to 14.  I had both my Amateur and GMRS for 20 years. I know many other licensees would say I wonder how Adam was able pass an exam and still come with comments that don't makes sense. I apologize for sounding uneducated, but I able to leave my cents.

Happy Holidays to All !

[OffRoaderX]

11 minutes ago, Adamdaj said:

I had both my Amateur and GMRS for 20 years.

Wow! OVER 20 years!?  I am very impressed! 

[WRQC527]

In this screen grab, we can see the end of an FCC-initiated high-speed pursuit that was the result of a perpetrator transmitting on a Wouxun KG-XS20G on channel 8. The FCC handed the chase over to the highway patrol when they realized they had no vehicles with which to chase anyone. 

[wrci350]

1 hour ago, Adamdaj said:

 I still don't see the reason for half watt on channels 8 to 14.

Because they are so close to the repeater input frequencies.  It's to minimize potential interference with repeaters.

(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.

They are only .0125 MHz away from the repeater inputs.

[AdmiralCochrane]

I feel the urge to ... no, never mind

[WRZT691]

5 hours ago, OffRoaderX said:

Wow! OVER 20 years!?  I am very impressed! 

I'm enjoying your youtube videos. I've been learning a lot by them. 

[Sshannon]

5 hours ago, Adamdaj said:

That question of yours about channel 8 through 14 makes sense. I read the FCC Part 95 subpart A, B, & E and I still don't see the reason for half watt on channels 8 to 14.  I had both my Amateur and GMRS for 20 years. I know many other licensees would say I wonder how Adam was able pass an exam and still come with comments that don't makes sense. I apologize for sounding uneducated, but I able to leave my cents.

Happy Holidays to All !

We’re all capable of making comments that are baffling in retrospect. Don’t beat yourself up about it. You seem like an honest and humble person which is much more important than being a smart-ass. 

[WRZU673]

On 12/17/2023 at 10:32 PM, WRYC373 said:

Short answer its to allow full compatibility with frs. Those channels were originally FRS only pre 2017.

Yes if operating a gmrs radio you need to by rule announce the same as any other channel.

 

Those channels if you look at frequencies are close to repeater inputs and the reason why power is low is to prevent any interference on the repeater inputs.

I was also wondering that, but figured FRS had something to do with it. I hadn't realized that those frequencies are close to the repeater input frequencies. Makes total sense to me now.

[WRYS709]

2 hours ago, WRZU673 said:

I was also wondering that, but figured FRS had something to do with it. I hadn't realized that those frequencies are close to the repeater input frequencies. Makes total sense to me now.

I disagree; it is just historical that FRS was originally limited to 0.5 watts. 

Channels 1-7 are also interstitial channels just as close to the repeater Output Channels, but FRS can transmit at 2 watts on these channels (and GMRS at up to 5 watts) and both FRS and GMRS can transmit right on top of the repeater output Channels 15-22 (at 2 watts and up to 50 watts, respectively). 

Oh oh: here comes the debate about the perceived increased interference on Input Channels…

[WRQC527]

1 hour ago, WRYS709 said:

Oh oh: here comes the debate about the perceived increased interference on Input Channels…

[Adamdaj]

On 12/19/2023 at 6:25 PM, wrci350 said:

Because they are so close to the repeater input frequencies.  It's to minimize potential interference with repeaters.

(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.

They are only .0125 MHz away from the repeater inputs.

That makes sense now! Happy Holidays

[Adamdaj]

On 12/19/2023 at 5:00 PM, OffRoaderX said:

Wow! OVER 20 years!?  I am very impressed! 

I know you could care less about how long someone has been licensed. I probable sound like more like confused HAM instead of just a Sad Ham. My new year's resolution for 2024 should be to research topics before for forming an intelligent opinion.  Hope you keep making good videos for YouTube, because in a way you remind me of what uncle Ray use to say. Don't give me S**T, just show it. 

Happy Holidays