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My first tower	Reply
by VE3TMT on March 20, 2009	Mail this to a friend!
As spring approaches and the date for putting up the tower draws near, time to ask some questions.. Here is the setup.. Tower is a Delhi 40' self supporting. I plan on sinking 4 feet of the base section into the concrete so the height at the top of the tower will be 36'. Plans are to mount a Cushcraft A3S at the 38' level, a Cushcraft A27010S at 43' and a 2m/440 j-pole on the top at 44'. All will be swung with a Yaesu G450XL. I also have an Alpha Delta DX-B that will run from the 36' level sloping east for the low bands, using the tower for the ground. As mentioned, this is my first tower, and I am very concerned about grounding, lightning protection etc. All my feed lines will be disconnected inside the shack during bad weather, but I want to make sure I cover all the bases. What is required on the tower side, and what precautions should I be taking in the shack? I can't really run a ground rod from the shack location, but I can get to the cold water pipes or the water pipes coming in from the street. Will this suffice? I appreciate any advice. Max VE3TMT

RE: My first tower	Reply
by K9KJM on March 21, 2009	Mail this to a friend!
IF you "disconnect" coax, Be SURE to put it to a good ground! Do NOT just leave it lay! (A much faster safer way is to just use a good coax switch that puts unused antennas to ground, Mounted on your single point ground panel) A few basics, Bond all grounds together, Flat copper strap is the best material to use (Think copper roof flashing, etc) Ground rods spaced twice the distance apart as the depth, Install a "whole house" surge arrestor in your electric service entrance panel. For some good info read; http://members.cox.net/pc-usa/station/ground0.htm For tips on how to do it all on a budget pick up a copy of May, 2009 Popular Electronics Magazine.

RE: My first tower	Reply
by K9KJM on March 21, 2009	Mail this to a friend!
OOPS! The upcoming article on lightning will be in Popular Communications magazine, Not Electronics. Sorry about that slip

RE: My first tower	Reply
by K2MK on March 21, 2009	Mail this to a friend!
Be sure you follow local building codes for your project. Obtain information from the manufacturer on the proper type of foundation. Preferably a drawing stamped by a professional engineer. File a permit request with your local community. Observe all inspection requirements. For example, there may be an inspection required after the hole is dug and before the concrete is poured.

RE: My first tower	Reply
by VE3TMT on March 21, 2009	Mail this to a friend!
I spoke to the city building inspector and was told no permit is required as long as the overall height of the structure isn't over 50 feet. He even asked if it was for "ham radio" and when I told him yes, his reply was "have fun, go at it". I have the hole specs for the tower as 41" x 41" x 48" deep. Should be a problem, but I may consider anchoring it to the house and going with a slightly smaller hole. The way the wx has been here lately it will be at least another month before I can start the dig. I am curious about lightning arrestors and that kind of thing. Max

RE: My first tower	Reply
by KB9CRY on March 21, 2009	Mail this to a friend!
Did you do a search on Grounding in the main forums page?

RE: My first tower	Reply
by K5CQB on March 21, 2009	Mail this to a friend!
Good for you on the permit thing but I suggest you find the exemption in your local codes and print a copy out for yourself. Get a card from this fella and attach it to where he said you didn't need a permit. I suggest you follow the manufacturers recommendations. If it recommends a particular base then use it. If it does not give plans to mount to the house, then don't do it. You may also consider that bracketing to your house will transfer wind/vibration noise from the tower to your house. 73, Jim K5CQB

RE: My first tower	Reply
by WB2WIK on March 21, 2009	Mail this to a friend!
I'd usually go "overkill" on the foundation and not use house brackets. Shovels and excavation are cheap, concrete's cheap, a new house isn't. If you plan on "disconnects," if you make those OUTSIDE, they're pretty good. If you make them "indoors," they're typically worthless. I'd use lightning arrestors on the lines, anyway, including the rotator cable. Ground the tower using clamps and heavy cable from tower legs to ground rods driven into undisturbed soil outside the concrete pad. Not sure the G450 rotator will actually handle the load you intend: I'd go for the G800 rotator. Good luck with the installation! WB2WIK/6

RE: My first tower	Reply
by VE3TMT on March 21, 2009	Mail this to a friend!
According to the manual for the A3S the wind load is .47 m2 whereas the rating on the G450 in a tower mount setup is 1m2. I guess I am fine. the only other antenna on the mast is the A270-10S which is .07 m2 and the J-Pole.

RE: My first tower	Reply
by WB2WIK on March 22, 2009	Mail this to a friend!
TMT: You forgot to include the mast and the length of mast from the top of the tower to each load in your loading calculations. Unless you use two thrust bearings between the rotator and the load, the loading on the rotator bearings, like the loading on the tower itself, increases proportionately to the height of the antenna(s) above the rotator. It's not just a matter of having sufficient torque to turn (and also stop) the load rotating, a strong consideration should be made for bearing load Having installed an awful lot of beams on towers, including a dozen A3S's, I wouldn't use the G450 for this. My guess: It will work fine for a while, and then by the end of the second winter it will stop working. WB2WIK/6

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