Tightly tensioned guy wires can put many times the compressive load of a single climber on a tower. If a tower were suspect, (or maybe just as a good precaution), the guy wires should be tensioned an
Here's another way to measure the tension in you guy wires, and all you need is a small tape recorder and 3 ft piece of 2 by 4 lumber. Cut two small blocks off the ends of the 2x4, and nail them to t
Sorry for the math error in my origianl post, when I hit the send key, the light came on ;>). Doubling the tension does not double the frequency. You need to have 4 times the tension to double the fr
Bill, I don't question that the numbers you got from the 1976 Rohn catalog are not faithfull reproductions, perhaps I just don't understand their interpretation. projection area" of one section of Ro
Vic, Check out the epoxy's at Marine Tek. I've used them, and they are very good, especially for outdoor applications with lots of moisture. As far as bolt depth, go as deep as you practically can. W
Well, why not wade into this interesting topic? Would have sooner, but spent most of the weekend working the SS CW contest with W8RJL's group under the K4IX call. Had a clean sweep and had a blast! L
Several gentlemen have pointed out that I mistakenly said the radius of curvature of the transmitted wavefront gets smaller as the signal emanates from the antenna. I apologize for the slip. I should
Clay, Yes, you're in the ballpark. The formula for drag is 1/2* rho*velocity-squared*frontal-area*coefficient-of-drag. I calculate about 26 lbs force for 90 mph for 1 sq-ft frontal projection area. T
Jim, Yes, I figured you used a Cd of 1.0, which is a reasonable starting place. Nice to know there is another "aero" guy on the towertalk list. Below is a link to some very good information on commun
Clay, Great question! Difficult answer. I'm assuming that the projected areas are the same for both the 1/2" and 2" tubing in your question. It may be counter-intuitive, but many times the smaller di
The tricky thing, of course, is that structural members for ham towers in typical winds are in that horrible Reynolds number regime around 100,000 where the Cd varies so quickly (and varies a lot dep
Jeff, The dip meter is a very versatile instrument, with very many uses. I own several makes, and use them regularly. Some of the applications are: 1) Receiver adjustments 2) Transmitter adjustments
Just curious as to why 55 ft was chosen. Seems like 65ft (about 1 wavelength on 20m) which would allow a good low angle radiation pattern on 14Mhz, would be better for hams. I wonder if they though
Does anyone have experience with red-tailed hawks...? Thanks, Doug K4AC Doug, While hang gliding in the Appalachians west of Charlottsville, VA, there have been many occasions when a Red Tail Hawk wo
Jim, Great info on stubs, and very timely given that Field Day is only 2 1/2 months away. A couple of quick questions: Does a higher "Q" coax yield more attenuation, all other things being equal? I k
Suppose I'm at Field Day, operating CW on 40m.Right next to me, a station is operating on 20m.I could use a stub to attenuate him. I could use a lumped element filterin my transmission line pre-tuned