I think I finally have a plan for base station

[ClemsonSCJ]

I have a similar situation here; even though I've not noticed the following problem myself (maybe we just have a clean furnace), I've had people mention tom me that some of the gasses coming out of a chimney can have some bad effects on metal & connections/solder....

That’s actually not the reason I wasn’t mounting to the chimney. My original plan was to do a chimney mount, but pretty much everyone on QRZ said that was a terrible idea. I naively thought that a massive brick structure protruding from my roof would be about the most solid structure I would find on my property to mount something like this to, but apparently I was dead wrong.

 

[jonwienke]

You want to dig down following the existing ground wires to make your own separate connection to the ufer ground, rather than piggybacking on the utility ground wire connection. If you get hit piggybacking, the utility ground potential is going to jump higher than if you make your own connection directly between the antenna and ufer.

 

[ClemsonSCJ]

You want to dig down following the existing ground wires to make your own separate connection to the ufer ground, rather than piggybacking on the utility ground wire connection. If you get hit piggybacking, the utility ground potential is going to jump higher than if you make your own connection directly between the antenna and ufer.

From my limited understanding of an ufer ground, what’s coming out of the ground is all I get. That copper line runs into the footer and is encased in concrete.

 

[mmckenna]

...but pretty much everyone on QRZ said that was a terrible idea.

Be careful what you read on QRZ. Like this website, it's often a lot of hobbyists and self proclaimed experts. Mounting to the chimney can be just fine if the chimney is reinforced. Some are, some aren't. Here in earthquake country, any modern ones are. It's very common to mount TV antennas, small satellite dishes and ham antennas off the chimney.

As for flue gases, making sure the antenna is up higher than the chimney top will address that.

 

[mmckenna]

From my limited understanding of an ufer ground, what’s coming out of the ground is all I get. That copper line runs into the footer and is encased in concrete.

You're fine. I have UFER ground at my house. It's a slab foundation.

Put your ground rod below the antenna to give any direct lightning a straight path to ground.
To meet NEC, you need to bond the two ground systems together. Run a #6 copper conductor from the ground rod to your UFER ground near the panel.

 

[ClemsonSCJ]

You're fine. I have UFER ground at my house. It's a slab foundation.

Put your ground rod below the antenna to give any direct lightning a straight path to ground.
To meet NEC, you need to bond the two ground systems together. Run a #6 copper conductor from the ground rod to your UFER ground near the panel.

Does it have to be 18” underground or can I run a #6 from one to the other and call it a day?

 

[mmckenna]

Does it have to be 18” underground or can I run a #6 from one to the other and call it a day?

You can run them from one to the other. Doesn't need to be buried.

 

[ClemsonSCJ]

You can run them from one to the other. Doesn't need to be buried.

That I can easily do. Thanks.

 

[chief21]

But if I do I would have to mount the entry panel to the wall below the soffit and then have the coax come out of the entry panel to enter the soffit. Would that not create the same problem?

Yes... but probably to a much lesser degree.

 

[AK9R]

Be careful what you read on QRZ. Like this website, it's often a lot of hobbyists and self proclaimed experts.

Much like here.

Masonry walls, whether they be concrete block (CMU), brick, or adobe, are strong in compression along the vertical axis. They aren't so strong when subjected to a side load. CMU walls for buildings must be carefully braced during construction so that they don't fall, especially in the face of strong winds. But, when the building's roof structure is applied and the wall is loaded in compression, the wall becomes stronger against side loads.

A brick chimney has no compression loading other than its own weight and it only needs to be strong enough to resist the side loading from the wind. That's why attaching a large antenna array to a chimney is generally a bad idea. The antenna and its mounting system increases the side loading and one strong wind will very likely result in your antenna and your chimney laying in the yard.

Once you get up on the roof, take a very close look at the chimney. If you see loose bricks or mortar that is cracked or eroded away, hire a brick mason to take a look at it.

While seismic reinforcements are common in some earthquake-prone parts of the world, they are virtually non-existent in others. Also, even if current building codes require seismic reinforcement, many older houses have none.

 

[mmckenna]

Much like here.

Which is why the entire line I wrote, that you chose not to include, said:

Be careful what you read on QRZ. Like this website, it's often a lot of hobbyists and self proclaimed experts.

So, right back at ya' winky boy.

While seismic reinforcements are common in some earthquake-prone parts of the world, they are virtually non-existent in others. Also, even if current building codes require seismic reinforcement, many older houses have none.

We'd hope that anyone going through all the effort ClemsonSCJ has will take a look and determine the construction of the chimney. Unlike what the lids on QRZ may claim, it's not a hard "NO" on mounting off the chimney. There's some thinking involved, rather than the typical knee jerk reaction you'd get from them.

I'll put my faith in Clemson over the QRZ people, he's shown some skill and knowledge in his posts, and he's certainly asking the right questions. I've been on QRZ, I can't say the same for them. There are only a few hams that I trust the opinion of. The rest of them scored at least 70% on a multiple choice test. Not rocket surgery stuff there. None of the ham radio tests cover building code.

 

[WB9YBM]

That’s actually not the reason I wasn’t mounting to the chimney. My original plan was to do a chimney mount, but pretty much everyone on QRZ said that was a terrible idea. I naively thought that a massive brick structure protruding from my roof would be about the most solid structure I would find on my property to mount something like this to, but apparently I was dead wrong.

Actually the brick-and-morter chimney's probably going to be more solid than thin strips of wood holding your shingles up--unless you attach a tripod directly to the joists--I've even heard of people putting cross-members under several joists for bigger tripod/beam arrangements for added support during high winds. (If in doubt, you might want to double-check with a professional roofer or contractor to make sure the next big breeze doesn't rip off you roof.)

 

[ClemsonSCJ]

Actually the brick-and-morter chimney's probably going to be more solid than thin strips of wood holding your shingles up--unless you attach a tripod directly to the joists--I've even heard of people putting cross-members under several joists for bigger tripod/beam arrangements for added support during high winds. (If in doubt, you might want to double-check with a professional roofer or contractor to make sure the next big breeze doesn't rip off you roof.)

I’m not putting up much. Right now I just have a DBJ-1 that’s going on a 10ft emt mast. Even in super high winds if something happened to my roof I’d probably assume it was doomed to begin with.

 

[ClemsonSCJ]

So here are my 2 options. The images should be pretty self explanatory but if it’s dotted it’s inside the attic or crawl space. If it’s not dotted it’s either outside or inside the shack itself. The first image is grounding everything to the #6 wire going to the ufer. The 2nd image is grounding everything to a ground rod that’s bonded to the #6 wire going to ufer.

Oh, and I drew the first image to simulate a generic roof since the design didn’t matter how I drew it. The 2nd image is more representative of how my roof actually looks from the back of the house, with the overhang on each side of the ends of the attic space.

 

[chief21]

I’m not putting up much. Right now I just have a DBJ-1 that’s going on a 10ft emt mast.

I've never cared much for emt as an antenna mast, since it can bend so easily. I used to use TV mast sections, but they're not so easy to find these days. A good substitute is a section of chain-link fencing top rail... 10' long, a little beefier than a TV mast, available at Lowes/Home Depot/etc. and not expensive.

BTW, image number 2 would be my preference.

 

[mmckenna]

I’m not putting up much. Right now I just have a DBJ-1 that’s going on a 10ft emt mast. Even in super high winds if something happened to my roof I’d probably assume it was doomed to begin with.

EMT would probably fold over before any damage was done. I think I used 1 1/4 EMT for a while on my chimney mount.

 

[mmckenna]

I agree with Chief. If I was doing that install at my own house, I'd go with #2 also.

 

[ClemsonSCJ]

Ok so then my plan will be to go with door #2 with a tripod mount on the edge of the roof. That should cut my coax run down quite substantially as well so that’s a win.

 

[ClemsonSCJ]

I know we said before that the bonding between the new ground rod and the main utility ground doesn’t have to be buried. But assuming I wanted to go ahead and do it so that I don’t have to worry about it when I’m cutting grass and what not, what kind of wire can I get at Lowes that is rated for direct burial? Cause apparently you can’t bury the #6 bare copper wire.

 

[mmckenna]

I know we said before that the bonding between the new ground rod and the main utility ground doesn’t have to be buried. But assuming I wanted to go ahead and do it so that I don’t have to worry about it when I’m cutting grass and what not, what kind of wire can I get at Lowes that is rated for direct burial? Cause apparently you can’t bury the #6 bare copper wire.

Right, it would corrode.

I believe a RHH or RHW-2 type wire is what you want for direct bury.