GMRS 12.5Khz

[matt131]

Hello,

Is narrow band or 12.5 Khz allowed on GMRS?

[gewecke]

The interstitial channels 1-7 are already 12.5khz...so yes they are already there.
ch.1 462.5625,and so on. Is this what you were asking ?
N9ZAS.

[matt131]

How about the regular GMRS channels like 462.550, 462.575 etc....

[gewecke]

Those are repeater outputs. They are 25khz.steps.
It starts like this; 462.5500,462.5625,462.575...and so on.
N9ZAS.

[matt131]

So I guess I can't use narrow band on GMRS for example if I set up 2 portables on 462.575 direct and used them on narrow band?


Can you do a GMRS repeater 462.575 on narrow band?

[gewecke]

GMRS and FRS channels are already on narrow band fm,as is gmrs repeaters,as is most uhf repeaters.
N9ZAS.

[matt131]

oh ok, I thought GMRS was 25khz

[n1das]

12.5kHz or 25kHz refers to the channel spacing for "narrow" and "wide" channels respectively. This is the channel spacing for each type, NOT the bandwidth of each. The occupied bandwidth (OBW) of each is slightly narrower. Channel spacing and OBW are not the same thing.

GMRS has historically been "wide" on the primaries AND on the interstitials, long before the bubble pack invasion began. GMRS can also operate "narrow" on the primaries and the interstitials. Take your pick.

OTOH, FRS (14-channels bubble packs) has been narrow from day one. The 22-channel GMRS/FRS bubble packs are narrow only on all channels, so they already are using narrow on the GMRS primaries.

For GMRS, I recommend running narrow only on the interstitials. On the GMRS primaries, I recommend running wide or narrow, depending on your preference and equipment capabilities. I for one are running narrow on all interstitials and GMRS primaries, and I'm using commercial-grade equipment instead of bubble packs. My UHF commercial radios specifically have FCC Part 95 Type Acceptance in addition to Part 90, so the equipment is legal on GMRS. (They're KENWOOD radios.)

I've had one of my GMRS repeaters get hit by FRS traffic on the upper FRS channels spaced 12.5kHz from the repeater input. The repeater is OLD (Kenwood TKR-820) and is "wide" bandwidth. My other GMRS repeater is wide/narrow capable and I'm using it in narrow mode to help prevent FRS from clobbering the input from 12.5kHz away on each side. It works.

A few years ago I finalyl stepped up to the plate and I'm running narrow mode on all GMRS primaries and on the interstitials. I found all of my adjacent channel splatter problems from bubble packs in my neighborhood wend away as soon as I switched everything to narrow mode. I also decided to go with the Part 90 flow of things where Part 90 services are in the middle of transitioning to narrower bandwidth and older "wide" equipment will become hard to get in a couple of years.

Even though I'm using good commercial-grade equipment, I'm operating narrow bandwidth like the 22-channel bubble packs already are. All of my adjacent channel splatter problems went away as soon as I made the switch.

[n1das]

Originally Posted by matt131

Hello,

Is narrow band or 12.5 Khz allowed on GMRS?

YES, it is allowed AND recommended.

1. FRS is narrow-only.
2. GMRS can be EITHER wide or narrow.
3. The 22-channel GMRS/FRS bubble packs are narrow on all 22 channels. They are narrow on the GMRS primaries even though they are not specifically required to be.

[matt131]

Thank you very much for all of your help. I really appreciate it. I am running Narrow band. I find less interference. Is it possible to get a little more range in areas with a lot of congestion with narrow band?

again, thank you for all of your help!!!

73

Matt

[gewecke]

Most of the gmrs repeaters I'm aware of all are prog. for nbfm as is my kenwood tk805d. nbfm on the interstitials as well.
I hope we've been able to help matt. You'll definitely have less interference on nbfm!
N9ZAS.
WPOK400