GMRS - setting "privacy", CTCSS or whatever it's called

Okay, for Moab and other trails I want to make sure the radios are set up ahead of time so we don't have to pull out manuals when airing down just to figure out how to use the radios. Here's what I'm thinking

• 22 (462.7250 mHz) which will also work with FRS and Ham

If it gets busy on that frequency with others not in our group, we should have available a preprogrammed or predesignated "privacy" channel, aka CTCSS. These appears to be a PITA solution because it's not standardized between manufacturers. Here's my thought:

• If we determine 22 is too busy, we'll switch while on the trail
• Enable CTCSS/Privacy/sub codes or whatever it's called on your radio
• Choose "2" or whatever corresponds to 71.9hz on your radio

So my radio geek friends, please share your thoughts on this, correct my thinking as needed and make suggestions to make communication on the trails easier. Please note that the H4O Radio Czar, aka LagunaH1, has been nominated to help everyone get onto the right channel as needed.

CTCSS (aka squelch tones) only make it so that your receiver doesn't open up audio unless the tone is detected, so that if someone else happens to transmit on the same frequency it won't break through the squelch (the setting that determines how strong an incoming signal has to be before the radio will output the audio). Doesn't stop anyone from walking all over us if they have higher power and is transmitting at the same time as someone in the group. And anyone on the same frequency as us will still be able to hear us unless they too have set their own tones on their radios. So we could be blasting away on someone else's channel and not realize it, thus forcing them to have to switch channels.

Main use for squelch tones in my experience is on repeaters where you don't want someone that just happens to be on the same frequency as the inbound side of the repeater breaking open the squelch every time they transmit. Usually it's a "close enough to be able to break through but far enough away to make it unintelligible" situation, or if it's a private repeater it keeps unauthorized people from using it since they won't know the right tone to set. So when they try to transmit on the repeater's inlet frequency the repeater will ignore the transmission and not re-transmit it on the outbound side. Repeaters are Duplex and will listen on one frequency and transmit on another frequency so that it's all in real time.


TLDR; we can certainly run tones but in reality I don't think it matters if we do or not, we still may have to switch frequencies.

To be honest the ranges we usually run if anyone comes that doesn't have a vehicle mount radio we can just have them use a handheld (I plan on having at least a couple with me in addition to the vehicle mounted radio), you can get a decent amount of distance on those and they're all pretty compact compared to a CB handheld. And it makes it much easier for the spotter if they can reach you from a handheld when you can't see them at all.

JPaul is dead on. CTCSS just makes our radios deaf to other radios not using the same tone. Alrock also has a really good point: The various radio manufacturers tend to have different ways of enumerating the tone itself, some call it "tone 1" others call it "code A", so on and so forth.

My recommendation would be to agree on a standard channel for us to use (without a tone) and a secondary and maybe even a tertiary channel we can easily and quickly switch to, if need be.

Finally, I would encourage everyone to learn how to adjust the squelch on their radios. If we are on the trail, and hear others use our channel, we can then either just switch, or adjust our squelch so we can't hear stations farther away.

Did we pick a secondary channel?

GMRS Channel 22 is outside the frequencies permitted for HAM's BTW. There is no (legal) interoperability between GMRS and HAM in terms of shared frequencies.

Edit: Since we are broaching the topic of best practice, I'd also like to recommend that we all set our radios to *not* run at the highest possible transmit power. The Btech mobile radios will transmit up to 50 watts (not sure about other radios, but I imagine it'll be comparable). Running high power is in most cases not at all necessary, and if you transmit for long periods of time (think 2 - 5 minutes uninterrupted) your radio can get very very hot. Finally, if we all run high power, we will just make the problem of channel congestion worse for someone else on the same channel, potentially far away, which is where this thread started in the first place.

Hmm, have a gmrs radio in the ZR2 but not in the H3 yet. Guess I get to order another one now. Sorry Sally it was needed. LOL

jakesz28 said:

Hmm, have a gmrs radio in the ZR2 but not in the H3 yet. Guess I get to order another one now. Sorry Sally it was needed. LOL

Click to expand...

My conversation with my wife is even better.

"Honey, I started the discussion of, and helped convince everyone, that we needed to switch to GMRS, so now I have to buy a radio for the truck." :giggle: