VHF / UHF - Race Radio Antennas, Mounting & Grounding

treys1

treys1

Member
Recent chatter about "race radios" led me to pick up a couple handhelds. They seem pretty nice and got me going on researching hard mounts.

So with CBs, you make sure that the mount is well grounded, including griding paint and powder coat off crucial areas and running ground straps, then painstakingly checking SWR, we all know that.

Problem is, info for VHF / UHF / Dualband is all over the place. So, all you VHF / UHF pros, if I run a dual band Browning BR-180- B 37" antenna on an NMO off my HiLift mount (has an antenna hole) which is mounted to my tire carrier, do I need to grind paint and powder coat off + add extra ground wires / straps, or just bolt it all up and roll?
 
I just ordered parts to set my Jeep up with GMRS... which is UHF... I don’t believe grounding is an issue with the VHF/UHF like it is with CB.
 
jesse3638 said:
While I'm no radio tech I don't believe there is any need to create a ground for VHF/UHF antennas.

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Not quite. If you take your ham exam you learn that ground plane is still a very important component for proper propagation and needed to minimize the reflected signal back down the transmission cable to get the lowest SWR. That being said. There are some antennas that are capable of working with no ground plane due to specific lengths of the antennas radiating element but this ins not the most efficient antenna




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robx251 said:
Not quite. If you take your ham exam you learn that ground plane is still a very important component for proper propagation and needed to minimize the reflected signal back down the transmission cable to get the lowest SWR. That being said. There are some antennas that are capable of working with no ground plane due to specific lengths of the antennas radiating element but this ins not the most efficient antenna




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I got my GMRS license and I’m going to install a Midland MTX275.. I picked that because its very stealth and I am leaving room above the rear view mirror for a 25-50 Watt HAM unit.

What I would like to do, is use the same antennae for both the GMRS & HAM by installing a coax A/B switch in the glove box. Do you see any issues with that?
 
robx251 said:
Not quite. If you take your ham exam you learn that ground plane is still a very important component for proper propagation and needed to minimize the reflected signal back down the transmission cable to get the lowest SWR. That being said. There are some antennas that are capable of working with no ground plane due to specific lengths of the antennas radiating element but this ins not the most efficient antenna




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Yes true. If you get an antenna with a built in ground plane which is properly sized,, then there is no need for grounding is what I should have said...haha.

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So going down the GMRS rabbit hole how do you go about getting your license? I went to the FCC website and all it did was confuse me even more . Are there actually radio police ? I mean if I’m out in the middle of the desert who’s going to know :dont_tell:
 
JT@623 said:
So going down the GMRS rabbit hole how do you go about getting your license? I went to the FCC website and all it did was confuse me even more . Are there actually radio police ? I mean if I’m out in the middle of the desert who’s going to know :dont_tell:
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The rabbit hole is deep and Nerdy as hell... And I don't know how they would find you or why they would want to.... But it is the law, and I did find if you want access to Repeater codes you need a registered call sign.

First you register with the FCC, then fill out the application and pay the $70. They will email you the license within a day or two.

Here is a good step by step I found:

https://baofengtech.com/step-by-step-getting-a-gmrs-license/
 
TrailHunter said:
The rabbit hole is deep and Nerdy as hell... And I don't know how they would find you or why they would want to.... But it is the law, and I did find if you want access to Repeater codes you need a registered call sign.

First you register with the FCC, then fill out the application and pay the $70. They will email you the license within a day or two.

Here is a good step by step I found:

https://baofengtech.com/step-by-step-getting-a-gmrs-license/
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:thumb: I think I got it thanks nerdy as hell is an understatement . so I’ve got the handhelds if I get the midland one to mount in the Jeep is it compatible with the beofeng ?
 
JT@623 said:
:thumb: I think I got it thanks nerdy as hell is an understatement . so I’ve got the handhelds if I get the midland one to mount in the Jeep is it compatible with the beofeng ?
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Short Answer: Yes.

Nerd Answer: if the handheld is a GMRS unit only... it's legal to transmit (if you are licensed). If the Beofeng is HAM... it's not. HAM is not supposed to talk to GMRS... But it does. :crazyeyes:
 
Thanks for all the input so far!

I am planning on getting my license and I do understand the ground plane part, but I'm specially trying to understand about the need / lack of a low resistance chassis ground at the antenna mount lug like a CB. Is that required for these as well? Would a ground strap ring terminal between the NMO and mount hole be the right way to go if needed?
 
TrailHunter said:
Short Answer: Yes.

Nerd Answer: if the handheld is a GMRS unit only... it's legal to transmit (if you are licensed). If the Beofeng is HAM... it's not. HAM is not supposed to talk to GMRS... But it does. :crazyeyes:
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I’ll have to take your word for it :cheesy: I’m to old to go any deeper into this rabbit hole :crazyeyes:
 
TrailHunter said:
I got my GMRS license and I’m going to install a Midland MTX275.. I picked that because its very stealth and I am leaving room above the rear view mirror for a 25-50 Watt HAM unit.

What I would like to do, is use the same antennae for both the GMRS & HAM by installing a coax A/B switch in the glove box. Do you see any issues with that?
Click to expand...

You are able to program the gmrs frequencies in the ham radio I would save the cash and just get a dual band ham radio now with a remote head and get a dual band 2m/70cm antenna especially if you make sure you get a two vfo radio so you can monitor both your gmrs and your ham band/repeater of choice on the same radio


Robert Ring
KC1IMA
Maine
 
robx251 said:
You are able to program the gmrs frequencies in the ham radio I would save the cash and just get a dual band ham radio now with a remote head and get a dual band 2m/70cm antenna especially if you make sure you get a two vfo radio so you can monitor both your gmrs and your ham band/repeater of choice on the same radio


Robert Ring
KC1IMA
Maine
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For Sure... I know that makes the most sense... But for now I am getting my buddies into the GMRS (no way in hell they are dealing with HAM) so I want to test out the MXT275 myself... Then once I get my HAM license I will install an ICOM 2300 in the Jeep..... Keeping things "legit" would be to use both units for GMRS & HAM... but time will tell if I just use the HAM for both.

So just to be clear... do you think I can use a manual Coax A/B Switch for both units to the same antennae without causing some kind of interference?
 
TrailHunter said:
For Sure... I know that makes the most sense... But for now I am getting my buddies into the GMRS (no way in hell they are dealing with HAM) so I want to test out the MXT275 myself... Then once I get my HAM license I will install an ICOM 2300 in the Jeep..... Keeping things "legit" would be to use both units for GMRS & HAM... but time will tell if I just use the HAM for both.

So just to be clear... do you think I can use a manual Coax A/B Switch for both units to the same antennae without causing some kind of interference?
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I don’t see why not given you are able to keep the swr in check. I don’t have any hands on personal experience with them in that use. But I know that hf guys use them


Robert Ring
KC1IMA
Maine
 
I would use a duplexer rather than an A/B switch. I'd imagine a switch would be quite lossy; and you wouldn't want to forget to flip it back over and inadvertently transmit over a radio without an antenna connected.

I used to run two radios, and just used two antennas, but eventually caved, and now I just use my Yaesu 8900r for both ham and GMRS; some need a mod (jumper removed) to work on both, but mine was missing that jumper out of the box. The general consensus is that it's not really policed, unless you're causing interference or other issues. In my radio I programmed the local GMRS repeaters, and labeled them accordingly, so when just out on trail runs we can make sure to avoid them. I also found a couple of shared Canada channels that were not allowed to operate on high power in my region, so did the same with those as well.

It's been a while, but to get your GMRS license, I believe you have to first apply for an FRN number on the FCC website... and once you've got your FRN, you can login and now see the options to file for the license. Not sure if that's changed or has been simplified since, but that's how it used to be (speaking of which, I should check on mine, lol... my GMRS is probably approaching expiration, if not already expired). I think you also need the FRN before taking your tech/ham license exam as well.
 
kbp810 said:
I would use a duplexer rather than an A/B switch. I'd imagine a switch would be quite lossy; and you wouldn't want to forget to flip it back over and inadvertently transmit over a radio without an antenna connected.
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Thanks for the info... I’ll do some research on the duplex.
 
So tons of reading about ground plane, adjacent metal, chassis ground, etc and I had an idea I wanted to run by this thread.

Would a little stainless angle screwed directly to the tub between the drivers taillight and the tailgate opening be a good spot if I am trying to keep it on the rear of the Jeep?

I am thinking of using this antenna which is 37" tall so the tip should clear the top of the Jeep if mounted there.

https://www.amazon.com/gp/product/B013PY035O/ref=ox_sc_saved_title_1?smid=A3OIC2DXBFCE1I&psc=1

AntennaBracket.JPG
 
treys1 said:
So tons of reading about ground plane, adjacent metal, chassis ground, etc and I had an idea I wanted to run by this thread.

Would a little stainless angle screwed directly to the tub between the drivers taillight and the tailgate opening be a good spot if I am trying to keep it on the rear of the Jeep?

I am thinking of using this antenna which is 37" tall so the tip should clear the top of the Jeep if mounted there.

https://www.amazon.com/gp/product/B013PY035O/ref=ox_sc_saved_title_1?smid=A3OIC2DXBFCE1I&psc=1

View attachment 356751
Click to expand...

I’m going to run the same antennae for my gmrs/ham setup... but I’m going to mount it on the other side... I’ll fab up a bracket that bolts to the top of the EVO tire carrier hinge. At least, thats the plan for now.

I see you have a lift on the passenger side though... Hate to see you put screw holes in the body of the Jeep.
 
TrailHunter said:
I’m going to run the same antennae for my gmrs/ham setup... but I’m going to mount it on the other side... I’ll fab up a bracket that bolts to the top of the EVO tire carrier hinge. At least, thats the plan for now.

I see you have a lift on the passenger side though... Hate to see you put screw holes in the body of the Jeep.
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Yeah I was trying to find a way not to put holes there as well but the more I read about them, behind the tire like the CB antenna or right next to the Hilift (the Hilift mount has an antenna hole), would throw the SWR off way too much.
 
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