Are you comparing an old Tri-Ex W-51 vs. the newer Tashjian W-51/WT-51? If so, the Tri-Ex is structurally different than the Tashjian version. The Tri-Ex had legs with 0.095, 0.083 and 0.065 inch wal
Since Phillystran has been unobtainable or costly, I've been recommending Mastrant-M to my tower clients. I've had Mastrant-M at my station for 5 years now and it's held up very well with little or n
Another reason I'm glad I chose Mastrant-M for my towers. The stainless steel duplex clips don't interfere with Yagi patterns. 73 Jim K6OK Tim K3LR wrote: "The problem is significant and is caused by
Dave AB7E wrote>> Personally, I think the idea of using multiple U-bolts is the best way to go. << I agree. And instead of shooting from the hip and guessing, with U-bolts you can calculate and engin
Sorry my Gmail messed up the line breaks and made it unreadable. Reposting for anyone interested in calculating U-bolt torsion resistance for masts. I'm fairly confident this method is a good approxi
In general here's how design wind speeds are determined: * The city, county or state adopts the Int'l Bldg Code * IBC in Chapter 31, Section 3108, defers all design matters relating to towers to the
Not my experience on the West Coast, unfortunately. What has happened in most jurisdictions is the Planning/Building people have, over the last 20 years, seen a lot of permit applications for cell to
There isn't one. Pascals are units of pressure, while mph and kph are units of wind speed. 1 Pa = 0.020885 lbs per square foot The 550 Pa criterion is roughly 11.5 lbs/sq ft of pressure. Basic wind p
Here's an example where I asked ChatGPT to calculate the bending moment strength of Rohn 45 leg tubing. It's quite straightforward, a simple equation, and ChatGPT fumbles it pretty badly here: K6OK:
GPT-4 is the smarter, next generation AI machine. Let's do the same technical question and see how it does. (Note: I got an e-mail from a really sharp experienced ham who caught my typo in my ChatGPT
Ed N1UR: "Europeans use the words tower and mast pretty inter-- changeably in my experience. It was clearly what we Americans would call a guyed tower." Seems the American tower building code committ
Dave Leeson wrote: "For antenna or tower use, avoid the eye bolts that are just bent in a circle" I don't quite agree with this broad generalization. If the open style eye bolt has a working load lim
Mike WB2FKO wrote >> QTH is north Florida so I want to make the setup as storm-proof as practical. Any insight appreciated.<< Virtually all of Florida is in a Special Wind Region (Hurricane Zone). Th
re Mastrant: have experience in the smaller sizes. Installed 5mm on two 25G towers at 65 ft 5 years ago. I haven't needed to re-tension them, creep has been minimal. No visible wear or degradation of
Dave, W6NL/HC8L wrote: "Thanks [to N7WS] for the link to the very detailed Weber papers. They clarify the issue. ." Yes, but as you alluded to, K5IU's analysis is only true in a world where the wind
Bob -- You are on the right track. It's a creeping problem where local agencies here in Calif have adopted extensive "wireless facility" ordinances requiring hearings, reports, and expensive fees and
John KK9A Not just towers. Utility poles, street lights, billboards, 3-story townhomes on zero lot line... all within the neighbor's fall zone. For whatever reason some local agencies have a double s
If your tower has legs made out of angle iron instead of tubes or pipe, you may want to have a structural engineering analysis done. Angle iron strength varies greatly depending on the direction of a
If I had 40-2CD parts laying around I would definitely use loading coils to make a 2-el beam for 30m. I would toss the Cushcraft coils and make my own high-Q coils. This will make the 30m beam lighte
Informative site, but not specific to 30 meters. For an excellent example of a 30m loaded beam, see Norm N6JV's website: http://n6jv.com/30meterbeam.html 73 Jim K6OK _________________________________