GMRS Radio for Vehicle to Vehicle Communication

[ckent323]

We will be travelling in our Truck/FWC camper along with another couple and their Truck/FWC camper.

Last trip through Canada that we did together we had problems using cell phones to communicate truck to truck due to lots of dropouts as well as challenge of international cell plans.

For our upcoming trip we have decided, based on a lot of reading, to add GMRS radios to both trucks. I have a HAM license but our traveling partners do not have a HAM license and are not interested in the study required to take the technician test so 2 meter is out. We have ruled out CB for several reasons not worth getting into.

We like the Midland MXT275 GMRS radio because the chassis can be mounted out of sight and everything is done using the controls on the microphone. (I am probably going to get a Wouxsun KG-905g handheld as well as I often scout areas away from the truck on foot).

https://www.amazon.com/Midland-MicroMobile-Two-Way-Integrated-Microphone/dp/B07FN2FBML/ref=sr_1_1_sspa?crid=NWNPKMJZQM82&dchild=1&keywords=midland+mxt275+gmrs+radio&qid=1621982979&sprefix=midland+mxt275%2Caps%2C233&sr=8-1-spons&psc=1&smid=A33O82Y9CWW4GL&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyTFdGTjRaWldYWUhaJmVuY3J5cHRlZElkPUEwMzk0NTgxMTJNVUEzSzRMOVpEQiZlbmNyeXB0ZWRBZElkPUEwMjc1Mzk0MjNHRDNNWVpFOFhNVyZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

I am not knowledgable about radio antennas. The questions I have are about antenna mounting and location. We will be taking the Alaska Ferry North (and if Canada opens up we will drive back). Overall height is an issue relative to a roof mounted antenna and I do not want to drill a hole in the camper roof or the truck roof.

I am wondering about a 6 db whip (32" length) that is mounted to a jack bracket and then bent over and latched for the ferry trip or even attached to the truck rear bumper. The issue is that the top of the antenna might only be a foot or so above the camper roof as well as mounted at one corner and I have concerns that will significantly reduce its effectiveness.

https://www.amazon.com/Midland-Antenna-Durable-Connection-MicroMobile/dp/B084BPXNC5/ref=sr_1_3?crid=202KJDXSGOMUF&dchild=1&keywords=midland+gmrs+antenna+6db&qid=1621982895&sprefix=midland+6db+gmrs+antenna%5D%2Caps%2C236&sr=8-3


Alternatively the Midland 3 db "Ghost" antenna (3-1/2" tall) looks appealing but not sure where to mount it. Maybe on a removable crossbar mounted to the Yakima tracks and centered over the camper (if that mounting provides a suficient ground plane it may be the best solution).

https://www.amazon.com/Midland-MXTA25-Antenna-Connection-MicroMobile/dp/B08429ZT37/ref=sr_1_3?dchild=1&keywords=midland+gmrs+antenna+3db&qid=1621982926&sr=8-3

My questions are:
1) How to assess ahead of time the camper body blocking the antenna signals if I mount an antenna to a jack bracket (or perhaps a bumper). Any rules of thumb before I make a purchase (I am assuming the Aluminum siding and Aluminum frame of the ccmaper will act as a shield to emissions from an antenna that does not extand above the top of the roof - is that correct)?

2) What constitutes a good ground plane. Is a mechanical connection to the camper via a patch of bare metal (via a bolt or clamp) to the jack backet or the Yakima tracks sufficient? That is, does the ground plane need to be a countinuous piece of metal directly under the antenna or is the camper (or truck body sufficient?).

I am hoping a few members knowledgable of antenna theory and practice and GMRS in particular can give some suggestions.


BTW: I am aware of the lower power rules for GMRS emissions in Canada vs US as well as the GMRS license that needs to be purchased (no test). We plan to operate only on the low power setting of the radios whenever we transmit in Canada.


Thanks,
Craig

 

[rando]

A good option is to use a fender mount NMO bracket, something like one of these:
https://cometantenna.com/amateur-radio/no-holes-mobile-mounts/antenna-mounts-and-brackets/
https://www.americanradiosupply.com/fender-mounts/

With older vehicles the panel tolerances are pretty loose so you could likely just bend something up to fit your truck using 1/8" almunium bar, which is what I did on my UZJ100. The radiation pattern is not ideal, but the ground plane is decent and the install and wiring are clean and easy without involving the camper. You are not trying to talk long distances here. With the NMO mount you can always switch the antenna out for a ham/cell/gps antenna at a later date if you need one of these.

If you are a ham, you could consider getting a dual band mobile that has the ability to be modified to transmit on GMRS frequencies (at reduced power) so that you would have the best of both worlds. This is not technically legal, but if you are respectful of the power limits, no one will know or care.

 

[ckent323]

rando,

Thanks for the suggestions and the links. I will look into the mounts.

I initially considered programming a dual band HAM radio and looked into it, however, after thinking about it and reading the Federal regulations for GMRS I prefer to operate within the regulations (which require any radio used on GMRS frequencies to be FCC certificated for those frequencies and compliant with the the Code of Federal Regulations Title 47 Telecommunicatons, Subchapter D, part 95 (ie. a GMRS specifc radio). That written, I suspect you are correct that the risk of being caught, particuarly if operating respectfully of power limits is probably low.

I do appreciate all of your suggestions.

 

[PaulT]

If you go the GMRS way or buy a dual FRS/GMRS radio, be sure to get the FCC license to stay legal. $70 for 10 yr license.
https://midlandusa.com/why-do-i-need-a-gmrs-license-how-do-i-get-it/


Paul

 

[ckent323]

PaulT,

Exactly.

I'm presently waiting for the FCC to update the licensing page with the new, lower $35 license fee that was aproved earlier this year, instead of the old $70 fee.

https://www.buytwowayradios.com/blog/2020/12/fcc-approves-new-ham-and-gmrs-license-fees.html#:~:text=Up%20to%20now%20the%20application,previously%20charged%20by%20the%20FCC.

 

[JWL]

Gee, I’ve had a couple GRMS radios I’ve had probably 25 years. I never knew those had to be licensed!

 

[buckland]

I bought the MXT275 MICROMOBILE® TWO-WAY RADIO.... very compact and is in my center console. Antennae wire is very thin goes out the slider rear window and it is a magnetic mount. The antennae comes with a small circular steel disk which has 3m tape on one side. I stuck that on the aluminum camper roof above and an inch forward of the passenger side roof buckle clamp. So the antennae mags to that ...cable down the side with a loose zip tie. The excess cable falls into the front of the truck bed so that when the camper is popped up the cable just rolls out and tucks away when down. The antenna is then above everything on truck.
I too was blissfully unaware of the license but will gladly pay $35 for the license .... As of May 16th still no site update on application.