Antenna Mounting Question

[DewAddict]

Hi All,

I am going to mount my 5/8 wave sleeve antenna to my chimney using a chimney strap mount. My question is how high can I safely go above the chimney using this type of mount with a metal mast? I was thinking 10-15'??? Not sure as this is my first mouting project. The antenna itself is about 1.5 lbs and 48" tall made out of copper piping. I will be properly grounding and running good coax.

Thanks,

Rob

 

[mass-man]

Do you want to guy the pipe? Are you using one or two chimney straps? Is this chimney on the top of a one or two story house!!!

Best guess...put up 15ft. and see if you think it is strong enuf. Shake the *#^% out of it and make that determination. If you don't feel good about it, pop off 5ft. I really don't think the five foot difference is going to make a lot of difference in what you can hear, unless you are on the fringe of the system you want to monitor.

And yep, you better properly ground it. For your sake, the sake of your gear and your house...and if a big thunderboomer comes rolling in, disconnect the scanner from the antenna and throw the coax out of the window!!!

 

[DewAddict]

Ok thanks for the info. Its a one story ranch and I am using one chimney strap mount. I want to get as high as I can safely go because I do live in the country away from most of the repeaters and towers.

I have a tree that hangs over the house and is much higher than the antenna will be, so hopefully it will take a strike before the antenna although I would assume some of the energy may be absorbed by the antenna. Its always a risk I know and I will not be running in a storm.

Rob

 

[consys]

A "thumb rule" I read when looking into this said to guy every 10 of mast. Where that came from I never found, but my ground mounted 18 foot mast shakes ALOT! (no antenna on it now). For my roof mounted discone I followed "the rule" and no problems with the mast, even when the wind destroyed the first discone.

 

[mass-man]

Can you get two straps on the chimney? Can you set the bottom of the mast on the rooftop, on a piece of styrofoam, or rubber or a cheap cork coaster or something like that. Just resting on the rooftop is going to give you more stability!!! So you might use all 15ft. of mast but really only be 8-10ft. above the chimney...

I do like the guy it at every 10ft. rule!

But give it a shot...I used a chimney mount for YEARS and it never even moved. Just like consys, I lost a couple of antennas to wind, but the mount stayed there for years.

 

[DewAddict]

After some reseaarch I think I am going to go with a tripod on the roof of the garage and then a 10' mast with guy lines. I'll be able to get higher up and less mounting on the side of the garage.

How do I keep the roof from leaking when mounting a tripod? I am new to this and I don't want any leaks. Just screw in the self-drilling screws and seal with silicone??? My plan is to turn my garage into a radio hut for some "guy" time as I am up late at night and I won't disturb my significant other.

Thanks for all of the input here.

Rob

 

[buffalogoat]

It's all about "windload area"! If the antenna itself is not that tall or that heavy then you should be fine but the tripod mount is not really that stable in high wind unless you secure the legs well with bolts through the roof! Also make sure you seal around the bolt holes well & keep your guy wires tight!

 

[DewAddict]

Ok so I had an idea....Can I mount my antenna to the tree trunk? The tree is probably
80' high with a trunk that is 1.5 ft thick. I can get more height if I mount it onto the tree than I can on the garage. I will use standoff mounts that keep it 4" from the tree. The only problem is if the 4 lag screws will kill the tree??? I am no tree expert and I know some things will kill certain trees.

Rob

 

[Al42]

Mounting on the tree is bad for 2 reasons. The tree can whip around enough to break the antenna and tear the cable, and 80 feet of cable (plus whatever it'll take to get to the house from the tree) will require some pretty low loss (read: expensive) cable. It'll also wear out - from all the flexing - pretty quickly.

Also, trees are lightning magnets.

As far as mounting on the garage roof:

Use lag bolts. Not the shields, just the bolts. Drive them into the centers of rafters. Coat the threads with roofing cement, drive them in (use a 1/2" ratchet), then pour roofing cement over the heads. I had a 3 foot tripod on my foor for about 32 years with not a drop of water coming through. (We replaced the builder's roof after that time, and I didn't need the tripod so it got trashed.)

 

[DewAddict]

Hi All,

Thanks for all the info and advice. I erected my antenna this weekend to a height of 20' via two 10' masts secured to the side of the garage wall stud using 4" stand offs. It works great for a home made sleeve antenna. I can talk easily 20-30 miles on simplex using a
30w transmitter and can hit repeaters as far away as 50 miles. I am able to hear saginaw dispatch which is about 72 miles away from me so I am happy. I could probably go further with a ringo or cushcraft of some sort.

Rob

 

[DewAddict]

If I wanted to guy my top section of mast, what would I use to connect the wire to the mast? Do I drill a hole in it and screw in a hook type bolt? Also, could I secure the other end to the garage wall stud via the same coneection? Its only going to be up 30' and I am using very light (1.5lb) antenna on the top.


*** I found what I needed to get. They call them guy rings but and they go between sections of mast. Now I need to find a place that sells them. Google has been unsuccessfull so far. ***

Rob

 

[Yokoshibu]

I tried looking at a few places.... you know I had adevil finding mast mount clips to support my coax / hardline...

http://www.tmastco.com/ - check that out you might be able to make one!