Amateur radio tower install – Part 1

On September 11, 2013, in Uncategorized, by wx4sno

40' of Rohn 25G tower

Several weeks ago I was fortunate enough to find a used Rohn 25G radio tower from a guy up the road just over the state line in West Virginia.  Originally a 40′ tower, the owner was left with it after the telecommunications company had no further use for it.  Loaded with a half-dozen large antennas, he used a torch and cut it off and let it fall.  After selling off the antennas, he posted the tower on Craigslist, which is where I found it after seeing the prices for a brand new tower ($600+).  After driving up towards Bluefield and seeing the tower first-hand, I knew right then and there that I wanted it.

The owner said they installed it right after hurricane Hugo came through (1989) and around the time of the big east coast snow storm (Storm of the Century, 1993), which would make it at least 20 years old.  It was still in great condition and no rust, thank’s in part to Rohn’s ability to produce rugged and reliable products.  I figured I would paint it after I bought it anyway which would help preserve it even longer.  The guy said it was installed free-standing in concrete with a base 30″W x 30″L x 30″D, which is less than a cubic yard of concrete.   Rohn recommends over a cubic yard of concrete for un-guyed towers (4′x4′x4′), so how it survived with such a load of antennas is unreal.  Still, I believe Rohn’s specs are way over estimated to provide headroom…even  30″ cubed is a lot of concrete…one (1) ton to be exact!

Painted tower sections

After getting the sections home, a few days later I pressure-washed and painted them.  I ordered some expensive paint designed specifically for towers made of galvanized steel and went to work.  Since this is a communications tower, I figured I’d go the traditional route and paint it the standard tower colors, orange and white.  The FCC has guidelines for tower marking and lighting, so I went by those.

The next step was ordering supplies and digging the hole for the base.  I decided I would go with a cubic yard of concrete, which is 3′ x 3′ x 3′ for a total weight of 3,280 pounds.  After taking a couple days to dig the hole by hand, I then used a mechanical mixer to mix the 40 bags of concrete.

Tower base and leveled form

While the concrete base was hardening, I decided to order some additional supplies for the new weather station.  I went with a wireless Davis Vantage Pro2 and also bought a soil moisture/temperature station to go along with it.  After I get the tower installed, I’ll then have to take some time to unbox  everything and get it installed.

Tower base after pouring

In the meantime, I went ahead and installed the grounding system for the tower.  I used 2″ flat copper connected to several ground rods around the tower.  The rods are spaced at 8′ and 24′ from each of the tower’s legs with the copper straps connecting them to the legs.  For one of the legs, I used regular round copper wire which then runs down the hill to the house’s central ground and to my cable entrance panel on the side of the house.  Expensive…but I believe it was worth it.  I’ll have all my cables grounded to this setup thanks to a second entrance panel that’s going to be mounted on the tower.  Inside the entrance panel are bus bars for grounding the coax from the antennas, as well as a ground setup for the anemometer and one for the scanner/weather band antenna that I’ll be installing.

Tower's entrance panel

So, that’s where I am right now.  I’ve got the tower sections assembled and just need to mount the antennas and install the coax.  The coax is due to arrive tomorrow; after that, my dad, father-in-law, and brother-in-law are coming over Saturday morning to help hoist the tower into position.  That’s going to be the tricky part…if we can get it done easily, I’ll be ecstatic.  I’ll add another post on this after I get the tower setup on Saturday.

 

 

 

 

 

 

 

 

 

 

 

 

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