When TIA-222-H comes out it will implement the ASCE standards. But the ultimate design forces between TIA-222-G and -H are roughly equivalent, so need to worry :-) Under -G, the 90 mph standard requi
I believe the TIA-222-G results are more accurate than what can be achieved with CFD modeling alone. As I understand it, the TIA numbers are based on a combination of empirical data from the field an
You are correct Kurt. I've had great fun reverse engineering old towers with little historical documentation and stamping them under 222-G. The same approach can be used on antennas as well. In an id
Thanks Kurt for the very interesting history of how antenna square footages came to be. If we walk through TIA-222-G it will illustrate Kurt's point that just giving a square footage isn't that helpf
The core problem here is the ham consumer is not being given compatible and concise data from which to make an informed choice. There's only one way for antenna ratings and tower ratings to fully com
I concur. I neglected to mention that about flat vs. round elements. That's another factor that should be listed when specifying the antenna's rating along with the topo, exposure, speed, etc. factor
Kurt, I believe that if hams drop kilobucks on towers and antennas the manufacturers ought to be more forthcoming with current and proper ratings data so the ham consumer knows what they are getting
I really enjoy using a 1970's vintage K&E theodolite. Very handy at the beginning of a tower project to set guy anchor locations so they are exactly 90 or 120 degrees apart, and at the end of the pro
Sigh, I wish he had used a different terminology. It's purely semantics but I think the phrase "crosswind principle" is misleading. It's a fictitious force that does not exist in reality. If you have
I bought a used OptiBeam 11-3. Your post probably explains why the previous owner replaced all of the original elements with DX Engineering tubing. Kurt has noted -- and I've seen -- some wear issues
It's straightforward to show that a square boom is inferior to a round boom. A fair comparison is 2.25-in round boom vs. 2.0-in square boom because they have the same cross-sectional area. Bending is
I ran a finite element model with two 15-foot booms, one made of 2.25 inch round, the other with 2.0 square. One end was fixed and the other end was left free, exposed to gravity in the Z axis and an
It is critical that when buying anchor bolts that you specify and require they meet the ASTM F1554 specification. F1554 pertains to structural steel bolts embedded in concrete. I helped some local ha
The use of simple geometry and statics assumes the tower is perfectly rigid. It isn't. With the lifting point at 25% of height and 50 pounds cantilevered at the end, the tower will bend somewhat at l
I see the "fall zone" issue as more of a political or social issue. In every city there are telephone poles, billboards, streetlights, traffic signals, flagpoles, etc., all within the fall zone of ne
Steve N2IC wrote: "If you are planning station changes anyway, my suggestion is to replace the 7300. It's a great radio, at a great price, for a SO1R station, but the A/D dynamic range limits it in S
Well, no, 100 kHz is intraband and the lesser blocking number is not what causes the 7300 to be incompatible out of the box with SO2R or Field Day. It's not harmonic bands, it's adjacent bands, becau
I'm not quite understanding the "probably"? If you calibrate a simple side force deflection meter with the actual rope, then it will fully take into account any anisotropic or nonlinear behavior. OP'
J-bolts are essentially obsolete. When the 2014 version of the ACI code came out, the design pullout strength of J-bolts were sharply reduced based on laboratory results that showed that concrete is
According to Rohn docs that I have, leg wall thickness differs between 20G and 25G. 25G uses 16 gauge while 20G uses 18 ga. Also, the braces are different: 25G uses 5/16ths while 20G uses 9/32 in. 73