Chimney "mounts" and "top rail"....
Good Morning,
It has been my past experiences, having put up tv antennas for a living, when I was young and flexible, (LOL!) that chimney mounts are never a good thing. #1. There is the case of crumbling mortar and loose bricks. Even if you have it "re-pointed", there is a "grounding" problem. You would need to run some #6, solid, bare, copper wire from the mast down the roof and down to a 8' ground rod, to protect your home from a lightning strike. It can happen, even if the antenna is lower that the surrounding trees.
Now, I don't know where you're getting 21' long top rail. Here at Lowe's or Home Depot, the rail is only 10' 6" long and is about $10. a 'stick'. If you are going to "swag" them together, the "couplers" they sell to do that, don't work for vertical installations. Instead, I use a piece of white PVC four feet long (2' between joints) and drill and bolt them together, over the "swag". This makes the connection stronger and doesn't bend when erected. ;-).
Instead of a chimney mount, I would suggest a mount that protrudes (like a 2x6) from the side of the house out past the roof rafters and slightly down to allow for rain run off. You can u-bolt the mast to that. This will allow you to lower the mast, later, should you need to do antenna work or replace coax. Also, I would not attempt to have the "mast" higher than 30 feet long, unless you can "guy" it.
A better method, would be to use a telescoping pole, like for old TV antennas, but, they are much heavier, more costly and shorter, nowadays. We used to be able to get them up to 50', now, your lucky to find a 30'er. :-(
In any case, be sure to ground the mast.
Respectfully submitted,
73,
Don/KA5LQJ/8W2308 unit 3
