Perhaps it is wise, when refurbishing a galvanized tower section that shows some rust, to inspect the inside of any tubular member for rust or other deterioration. Rust is a symptom of deteriorating
Two thoughts: The underground tank is subject to corrosion that will not be seen. A leak underground may, as happened in a Minneapolis suburb in the past couple of years, follow the gas line into the
I agree there is little chance of a lightning flash from a guy line or other part of the tower installation as long as the ground systems of all components are tied together and all are adequate to l
Hello, TTers; Regarding ground level or slightly below ground radials under a vertical antenna: They don't work like a ground plane or counterpoise, in which dimensions are essential to resonance of
I wouldn't build on a guess if that tower is placed where it might fall on something valuable. It isn't very difficult to calculate dimensions for a base that will resist a specified overturning mome
Hi, TTs; Ground resistance and ground impedance are not nearly as important for lightning protection as is preventing differences among the several grounds involved and preventing excessive surges on
Any of the stainless steel alloys are suitable for grounding an antenna element to the boom to prevent arcing. Moderately high impedance won't prevent them from limiting the voltage difference betwee
Please excuse the error in the third paragraph of the earlier post. Higher permeability increases resistance, not frequency, because it reduces the depth of current due to skin effect. ______________
Hi, Peter; Skin thickness, the depth of effective current carrying, is greater in the non-magnetic stainless alloys. Skin thickness varies inversely as the square root of permeability, resistivity, a
The ARRL Antenna modeling course was, a few years ago, among the best of the ARRL offerings. 73 de WOØW _______________________________________________ ________________________________________
It is the result of differing routing of the messages. Email travels at nearly the speed of light, but sometimes arrives by way of Pluto. 73 de WOØW ___________________________________________
I bought wire at a farm store, cut it into pieces as Lee describes, and bent a short hook onto one end of each piece. To bend the ends quickly and easily, I clamped two nails in a vise about 3/16" ap
Don't put copper in contact with galvanized steel. It will remove the zinc and the steel will rust and may fail. Clean joints should be sufficient. Conductive anti-corrosion compound appropriate to g
Hi, TTs; Be aware that antennas on the sides of tall structures are not protected from lightning strikes by the structure. The "cone of protection" concept applies only to relatively short structures
Responses below: Read Uman and Rakov for info re the rolling ball concept of protected volume. You are correct; whether or not a specific installation will be damaged is a probability issue. The near
The rolling ball does not generate a cone of protection. It defines a volume no higher than the radius of the ball in which there is protection. To define a volume in which protection is 90%, use a b
An earlier post included information from Hank Lonberg, P.E./ S.E., KR7X that addressed welding rebar. Among many points Mr. Lonberg made, ASTM A 706 is a weldable reinforcing bar. A major redi-mix f
Both will rust, outside the concrete. The alkalinity of the concrete will delay corrosion of the steel inside the concrete, but this protection will be lost if there is an opening below ground that p
The optimum pattern of radials for lightning dissipation from a tower or vertical antenna is a pattern of 6, equally spaced around the center. More won't hurt, but don't help a whole lot for dissipat
Don't use braided cable for lightning dissipation, especially outdoors or in any environment in which corrosion will occur. The high frequency components will be concentrated on the outside of any co