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Always on power in cab for GMRS radio

Discussion in '3rd Gen Tundras (2022+)' started by Paul Moll, Dec 31, 2023.

  1. Dec 31, 2023 at 6:02 PM
    #1
    Paul Moll

    Paul Moll [OP] New Member

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    I installed a GMRS mobile radio in the center console, accessible by sliding back the little drawer thingy. Now I need always on power in the cab area ideally. I've seen the pictures of running a power cable to the battery through the firewall on drivers side. Looks doable, but surely there is always on power somewhere in the cab. Any ideas appreciated.

    Sorry if this has been discussed before, I did spend an hour scouring the forum but didn't find anything other than firewall to battery installs.

    Thanks and Happy New Year :)
     
  2. Dec 31, 2023 at 6:07 PM
    #2
    Black Wolf

    Black Wolf Bigfoot Hunter, Sasquatch too, but not Yeti

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    I attached my Midland GMRS trigger to my ACC fuse with a piggyback standoff fuse. Yes, I have a Frontier but the same difference. You need to locate your ACC fuse location. Edit...not always on. Only when ACC or "engaged" while driving.
     
    Wallygator likes this.
  3. Jan 1, 2024 at 9:46 AM
    #3
    bullet3z

    bullet3z New Member

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    Few questions for fellow GMRS guys.

    Way would you want power to the radio all the time. I would be afraid that I left it on while away from the truck and I come back to a dead battery.

    Are you getting better transmit and receiving ability with the radio in the truck vs a hand held unit?

    How did you mount the antenna and run the cable out of the cab?

    Are you getting a lot of GMRS radio traffic while driving around?

    I am currently running portable radios and not hearing anything while driving around. I hear more on Zello if I have the app on.
     
  4. Jan 1, 2024 at 10:07 AM
    #4
    Paul Moll

    Paul Moll [OP] New Member

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    Good questions bullet3z.

    Here's my experience..

    I want to have the GMRS mobile powered all the time since there are times in the Idaho outback my wife frequently stays in the truck while I wander out looking for wild horses. So keeping in contact with her is critical.

    Hard to say about whether the mobile is better than a handheld, don't have enough experience with that yet. But...this is a fair question as at 462MHz the wavelength is short enough that both the radiation efficiency of the handheld is good (I can explain if you're interested) and the propagation from inside to outside the vehicle is also pretty good. Further, an external antenna has it's problems such as high angle of radiation is common if not installed correctly. My antenna is 2m/440 dual band ham mag mount from Amazon. I choose that particular one because some people found it tuned higher than the 440 ham band, more like GMRS. I found it to be a bit below GMRS so trimmed 3/8 from the whip and bingo it's spot on for GMRS and also 2m ham. Perfect for my use.

    I can add one handheld to handheld experience, one inside one outside truck: Got good conversation with only small signal breakup over distance of 1 mile AND an 80ft tall and 1/2 mile wide hill in between. Further, there was nothing else around to reflect off of, I mean like nothing as on both sides of the hill was a deep valley. So I'm guessing the RF did not go "through" the hill, but rather either refracted off the top/sides or reflected off of a rock at the top. Both are very high loss for 462MHz on dry Idaho outback rocks and dirt. So I consider this quite range good actually.

    I ran the cable under the rear seat and out the back of the cab through those plastic flapper vents near the floor that I think are intended to let the cab air pressure neutralize when the doors are closed. Some people have advised against using that air path, but when I look at the cable going through it's keeping only a small part open full time. It's a tall reach from laying under the truck, and requires loosening the in cab large plastic panel behind the rear seat to grab the incoming cable. But once you have it fished in you're free to go where ever you wish with it. My GMRS radio is in the center console with it's OEM bracket "attached" to the coin holder slots via short bolts and large washers slid into the coin slots. It could be just lifted out with a bit if a tug, but is a small radio and secure enough.

    No idea on GMRS traffic driving around. I try to stay away from CB like chit chat and thus try to stay away from repeaters and keep a CTCSS code to filter out such. I do keep a local wide coverage repeater freq programmed in case I need to call for help from the outback :)

    About draining the truck battery...this is a good question too and I don't have it fully figured out yet. Currently I'm running a 12v Lithium pack charged by USB to 12v converters plugged into the rear side of the console USB jacks. But, I found out that these 12v Lithium batteries are just that, 12.0 volts and they go down to 11 volts about half way discharged which is not enough to power the GMRS radio on TX. So I'm currently planning to get full time 12v+ from the truck battery, then use a low voltage cutoff circuit board. I found this on Amazon: https://www.amazon.com/dp/B0C2VMGCZR?ref=ppx_yo2ov_dt_b_product_details
    Have not used or installed it yet, as I need to find in cab full time truck battery juice. I'll set the cutoff voltage high enough to keep some decent charge in the truck battery while still operate the GMRS radio for a while. These cheap Chinese GMRS radios these days have really low standby power consumption, like 1 watt or so. The truck battery should be able to run that for a couple of days and still have lots of power to start the truck. And of course a few minutes of engine run time will top off the truck battery to do it all over again. I use my truck every day so I'm not expecting any noticeable impact. But like I said, I have not actually done this yet, still planning.

    I'd like to know your mobile GMRS experiences too :)
     
    Last edited: Jan 1, 2024
    Willie64, Wallygator and equin like this.
  5. Jan 1, 2024 at 12:29 PM
    #5
    KroppDuster

    KroppDuster Out with the old and in with the...older?

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    @bullet3z

    I use both types: handheld units and mobile (truck) mounted units. IMO, both have their place. When we're out & about on trails, I tend to carry both. The handheld is great when I'm away from the truck while hiking, etc. However, to get the same reception on a handheld that I get on my good mobile unit while I'm inside the truck, I have to carry a magnetic mount in order to have the antenna on the roof and a coax extension in order to connect the magnetic antenna to my handheld. I've ran this setup before. It's fine. But, at some point I got tired of going back & forth and wanted a clean and permanent install.

    Wattage makes less of a difference than your antenna setup does, but more wattage does help in certain situations. Per FCC Section 95.1767, mobile & base units and repeaters are allowed to go up to 50 watts. Handheld units, as I recall, are limited to a max wattage of 5 watts.

    My mobile unit in the truck is a Wouxon KG1000 GMRS Mobile and I carry a BTech GMRS-V1 handheld unit when we're hiking. You can see my GMRS install on my build thread, if you're curious.

    As for GMRS traffic: In my neck of the woods, there is a lot of GMRS traffic. Locally, most of the off-road community here has switched over from FRS to GMRS in the last few years. Overlanders, Crawlers, Desert Racers, and the (no joke) hundreds of Can-Am & Polaris side-by-sides that run around here all use GMRS. We have a lot of traffic on the repeaters too.

    For highway driving, since my Wouxon unit can receive on multiple channels, I usually monitor Channels 15, 16 or 18 while scanning all other channels on the other band. I hear a fair amount of radio traffic while highway driving too. I can't speak for the east coast, but I hear a lot on the highways in NV, CA, AZ, and UT when we're bouncing between national parks.
     
  6. Jan 1, 2024 at 5:24 PM
    #6
    bullet3z

    bullet3z New Member

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    Currently I have several Baofeng portable radios setup for GMRS. When I applied for my GMRS license I picked up two Wouxun portables. They are nicer that the Bfengs. I have a repeater local to me that I can hit from my radio if I am close enough. I can receive from it at a further distance. When I was accepted to the repeater group by the owner he told me to download the Zello app and access the repeater group from my phone.
    https://zello.com/
    It is nice to be able to hit the repeater from anywhere as long as I have cell coverage. Unfortunately that is not always the case.

    I took some portables along for a drive south to the eastern seaboard. Unfortunately no one was transmitting on channel 16. I had hoped that there would be some traffic. I just don't think I can justy a mobile unit but I my try a home based unit.
     
    KroppDuster likes this.
  7. Mar 7, 2024 at 4:55 PM
    #7
    Glaurung

    Glaurung New Member

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    I do not have a GMRS radio at this time but can answer a couple of your questions. Does mobile GMRS radios have an auto off function you can set for a couple hours or so? If so there is no problem with them running all the time since the function would shut them down to save the battery. On the transmit and receive ability the radio will be better with an outside antenna for both, but especially so with the transmit. Use a mount such as the Comet trunk lip mount on one of the doors and run the coax through the door at the floor seal. Or use a through window mount. The glass mount will suffer some loss but can be used.
     

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