Brand new to GMRS - looking for antenna advice

[cuisinartoh]

I've spent the last 5 days since my post asking for radio advice reading up on all the recommendations for HT and mobile recommendations. I'm taking a break from that and pondering my feed line routing, antenna mounting, and antenna options. I am newly licensed for GMRS and studying for my tech class amateur license.

I attached pictures of the back of my house for reference and the gable end of the far right side. My office and "radio room" is the room on the far right, first story, above the windows in the basement. I can relatively easily get some LMR-400 to the far right gable end of the roof over the office. With some extra effort, I think I can get some LMR-400 to the far right gable end of the of the upper roof. This neighborhood is governed by an HOA and while there is no specific prohibition against antennas, there is a default provision that states anything attached to the house is subject to approval. I get it and I understand. So, with this background, I'll ask my questions.

Question 1:
For my purposes, I think it makes sense to consider mounting a dedicated UHF antenna for GMRS on the lower, far right of the roof. Since I don't want complaints, I'm thinking a commercial (as in purchased) omni is is a good idea since this antenna will be the most visible. Can anyone recommend a good commercial antenna for my base use with GMRS frequencies?

Question 2:
How do you recommend I mount the antenna? We get the occasional gusty winds here and three years ago we had strong enough straight-line winds that got me a new roof.

Question 3:
I'm not sure how to ground the mast of this antenna. My TV antenna is on the chimney so running a ground was easy. With the roof edge mount, I don't know how to ground the mast without running a ground wire along the roof and down to the ground. That might look ugly. Any thoughts? I am assuming running a mast ground inside the house and bonding it to the ground in my electrical system would be bad. I can't get a ground wire from these locations all the way back to the earth ground where my panel is. But I can get to a 12 gauge or 16 gauge ground in an electrical box in the attic. I think I could even fish down to bond to a water line in the garage.

Question 4:
Do you have a recommendation for a good commercial 2m/70cm antenna? It'll mount pretty much the same way as the GMRS antenna (on the edge of the upper roof) but this antenna won't be nearly as visible. I think an omni antenna here would be best too. I've seen some Comet fiberglass whips with short ground plane radials that seems visually unobtrusive.

Question 5:
Do I ground the coax through a lightening/surge arrestor outside near the mast or inside the house? If inside the house, can I ground it house wiring ground?

Question 6:
Since LMR-400 is so darned stiff, I'm thinking of terminating the feed lines to a wall plate with bulk heads (assuming this is a good idea). Can I then use a short length of more flexible coax from the radio to the wall plate with bulk head? If so, what would you recommend here?

Question 7:
If I'm asking questions that are too obvious and you can point me to a book for newbies that addresses all of these, please point me in the right direction.

Again, thank you all for any advice you have. I wasn't sure where to post this question since it covers both amateur and GMRS antenna questions. If I posted to the wrong forum then please let me know.

 

[mmckenna]

Question 1:
For my purposes, I think it makes sense to consider mounting a dedicated UHF antenna for GMRS on the lower, far right of the roof. Since I don't want complaints, I'm thinking a commercial (as in purchased) omni is is a good idea since this antenna will be the most visible. Can anyone recommend a good commercial antenna for my base use with GMRS frequencies?

Lots of choices. You need to consider not only the frequency, but the gain. A higher gain antenna will give you a higher ERP (Effective Radiated Power), but it'll also be taller. Finding a mix between size and gain is what you need to figure out. Not sure where you are, but generally you may want higher gain if you are out on the plains where the "radio horizon" is far off. If you are closer to the mountains/hills, etc. Lower gain might work better. I used to use a Comtelco base antenna on GMRS. Good idea to stick with a known good brand, but it's up to you.

Question 2:
How do you recommend I mount the antenna? We get the occasional gusty winds here and three years ago we had strong enough straight-line winds that got me a new roof.

Use purpose built mounting hardware. Keep mast height low. Use the smallest antenna you can get away with, which will keep wind loading down.

Question 3:
I'm not sure how to ground the mast of this antenna. My TV antenna is on the chimney so running a ground was easy. With the roof edge mount, I don't know how to ground the mast without running a ground wire along the roof and down to the ground. That might look ugly. Any thoughts? I am assuming running a mast ground inside the house and bonding it to the ground in my electrical system would be bad. I can't get a ground wire from these locations all the way back to the earth ground where my panel is. But I can get to a 12 gauge or 16 gauge ground in an electrical box in the attic. I think I could even fish down to bond to a water line in the garage.

National Electric Code covers grounding. All your grounds need to be bonded. That means the ground for your TV antenna, GMRS antenna and building electrical ground all need to be connected. Might be easier to mount your GMRS antenna above your TV antenna. Spend additional money on the coax cable, get better/lower loss cable to make up for the longer cable run. If your TV antenna stayed up during the high winds, then adding a small base antenna on the top would probably work.

Question 4:
Do you have a recommendation for a good commercial 2m/70cm antenna? It'll mount pretty much the same way as the GMRS antenna (on the edge of the upper roof) but this antenna won't be nearly as visible. I think an omni antenna here would be best too. I've seen some Comet fiberglass whips with short ground plane radials that seems visually unobtrusive.

I don't have any recommendations. Lots of posts on here about them, though.

Question 5:
Do I ground the coax through a lightening/surge arrestor outside near the mast or inside the house? If inside the house, can I ground it house wiring ground?

No. This is a good place to either sit down and read the National Electric Code or talk to an electrician.

For grounding the coax, the professional installs would have the outer shield of the coax grounded near the top of the mast and again near the bottom of the mast. A lightning arrestor would be installed before the coax enters the home and that would be grounded to a ground rod as well as the rest of the ground system.

You don't want to use the house wiring as a lightning ground. If lightning did strike, either directly or just nearby, you'd pump all that energy through your entire house. That would be bad.

Question 6:
Since LMR-400 is so darned stiff, I'm thinking of terminating the feed lines to a wall plate with bulk heads (assuming this is a good idea). Can I then use a short length of more flexible coax from the radio to the wall plate with bulk head? If so, what would you recommend here?

Yes. This is exactly how to do it. Trying to connect a stiff coaxial cable directly to a radio is asking for trouble. It is stiff enough that it can damage the antenna connector on the radio. It's very common in the industry to use a more flexible jumper to connect to the radio.

LMR-400 often gets referred to on this website as the Holy Grail of cable. It isn't. It's good stuff and suitable for hobby use in many cases, but you'd really want to look at the entire cable run, frequencies used, etc. to determine which cable you should be using. You may be OK with a lower grade cable. You might want something better.

Anyway, using something more flexible for your jumpers is a good idea. Even short lengths of RG-58 are suitable for this. There are any number of choices. Just make sure you get a cable with the correct connectors on the end rather than trying to use adapters.

Question 7:
If I'm asking questions that are too obvious and you can point me to a book for newbies that addresses all of these, please point me in the right direction.

ARRL Antenna Handbook is a good resource. It's aimed at hobby users, so it's pretty appropriate. I'm not 100% happy with everything they cover in there. Looking at commercial install guides is really a good idea, but the terminology and techniques can get pretty deep.

A few things you could look at:
Harger Specification Information

The Motorola R56 guide for site grounding is considered the gold standard. You can download it here:
https://sites.auburn.edu/admin/faci...ject Documents/1/Motorola_R56_2005_manual.pdf

Again, thank you all for any advice you have. I wasn't sure where to post this question since it covers both amateur and GMRS antenna questions. If I posted to the wrong forum then please let me know.

Keep asking questions. It's the way to learn.

 

[mmckenna]

If HOA's are a concern, you could give one of these a try, or make your own:
Untitled

 

[cuisinartoh]

Thanks again mmckenna. First, the good news. My FIL owns a commercial and industrial electrical business. His guys do all my more complicated wiring. In fact, I had them put my TV antenna for me during another job they were doing. They bonded the mast to the primary grounds that my panel goes to. In the picture above, my utility room is in the basement right below the fireplace. My office/radio room will be on the other side of the house. The basement ceiling is drywalled and does not have removable tiles. That makes things interesting.

My original thought was to rig up a mast with side arms and mount my GMRS antenna and dual-band antenna's above and off to either side of the TV antenna. But I was told by a local radio guy that having those antennas so close to my TV antenna would mean every time I key a mic the TV antenna would pick that up and garble the signal. If talking to my buddy screws up her TiVo recording of "Scandal" then I'm a dead man. So, if you have any thoughts about putting the 144/440 dual-band and 462-467 GMRS antennas within about 4-5 feet of each other? How about having either one so close to my TV antenna?

So even if I can get away with putting antennas so close to my TV antenna, I solve my grounding problem, but then I have to run coax a heck of a lot further. At a buck or more a foot that begins to add up. But, I'd rather do it right the first time. If I put my antennas where I suggested in my original post, then I have to run a large copper ground wire from the utility room, across the basement, and up into the attic. So I guess either way I have to do some ceiling fishing in the basement. Luckily, I had the guys leave some poly line in the ceiling from the last runs of CAT6.

Regarding coax, once I figure out where the antennas can be mounted and how to mount them, then I'll calculate run lengths and come back to ask about the right type.

If anyone has a list of brands and/or sites I can google please let me know. I'm so new to this that I don't really know what my options are. So far I've heard of Comet and Diamond antennas. I hear about someone named Dr. Fong. If I can mount on my chimney then I know my options.

Thanks!

 

[mmckenna]

If you can mount a single antenna directly above the TV antenna, and a few feet up, you would -probably- be OK. Putting two out to either side is probably going to be problematic.

So, scratch that idea....

I'd have them install a new mast on the roof peak as close as you can get to your radio room. Have them bond it to the house system as well as sink an additional ground rod directly under it with a straight (as possible) run of heavy copper down to the rod.
Mount your two antennas on that. I'd strongly suggest putting one of them up high and the second one well below and off to the side. Putting them too close together is going to result in radiated RF getting into the other antenna. You need both vertical and horizontal separation for it to work well.

I've only been in Ohio a few times. Every single time there were some serious (for me) lightning storms going on. Sounds like you've done this right having the electricians do the install to code. I'm pretty fortunate to live in a very lightning free area. Very rare we get lightning storms here.

 

[cuisinartoh]

Lightning and tornadoes are what we get. Occasionally we'll get a rogue hurricane that keeps itself together enough to bring sustained high winds. This actually happened to me in 2008. Lost power for a week after that one.

Anyway, if we're back to mounting on the opposite side of the house, then so long as my electricians can make the runs, I might as well do both antenna mounts and have them run grounds to the attic. That keeps the antennas more separated and keeps the load on the mount to just one antenna. Fortunately, labor and general materials don't cost me anything. But I'm at the mercy of scheduling their time around paying gigs.

I've seen the Ventenna before from another post you did some time ago. I think I can get away with fiberglass whips and small radial ground planes so I don't have to be 100% stealth. But I'll drive around the neighborhood and do a visual survey and have an off-the-record conversation with one of our HOA trustees. I used to be on the board but antenna questions never came up during my tenure

So it seems you've given me enough info to narrow my research. Thanks again! Too bad you aren't close enough for me to buy you a beer.

 

[mmckenna]

Thanks again! Too bad you aren't close enough for me to buy you a beer.

I'm always glad to help. I had people help me out when I started and I've always tried to pass that on.
A cold beer would be much welcome. If I was close, I'd be happy to assist.

The Venttenna's work, but they are probably just a 1/2 wave antenna, so they don't have any real gain. Sort of a compromise to allow you to sneak an antenna in where it's not supposed to be. If you can talk to your HOA and explain what it's for, and impress on them the low visual impact, you'll probably have a good outcome. Most HOA boards are made up of reasonable people.

A good quality dedicated antenna, designed for the frequencies you want and all properly installed is going to work very well.

For a dual band amateur radio antenna, Diamond makes some nice ones. If you can, go for the model with the type N connectors. They performa a bit better than the UHF connectors. Make sure you properly weather seal all the connections, getting water in the coax will destroy it.

For GMRS, you'll need a commercial radio antenna. While some amateur radio antennas will sort of cover GMRS, they're on the fringes and they don't work ideal. Getting an antenna that is specifically designed to work over the 462-468MHz range will be necessary. Shouldn't be hard to do, this area of the spectrum is heavily used by commercial, public safety, etc. users, so lots of good antennas out there.

Make sure whatever you do get, it's good stuff. It's a real pain to put all the labor into install, only to have it fail a few years later. A properly installed antenna system using professional grade parts is a work of art in my own option. HOA's may disagree, but I really do think a good antenna install is a lot less of an eyesore than a poorly installed antenna.