The wind loading might be less with a suitable cover over the coil than just the coil hanging in the wind. Small wires are quite draggy, compared to a streamlined strut. A working Cd for a small wir
One could wrap the coil in something that has good RF and UV properties. Some sort of UV inhibited Polyethylene might be good. Saran Wrap (Poly Vinylidene Chloride - PVDC) has nice mechanical and RF
Don't bother with Teflon... use High density (UHMW) polyethylene cutting boards... Less than $10 at your local discount store.. Very good dielectric properties, easy to cut (make sure that saw is SHA
Excellent idea.. The tape is essential. Milk jugs get brittle real fast (a month or two at most) in the sunlight, but the tape will block the UV. The part inside the pipe won't see the UV so it's not
Black paint often uses carbon black as a pigment. Carbon black, being conductive, makes a fine absorber, although, depending on density and thickness it may or may not have a significant effect. Like
Fully dried.. presumably you mean fully cured, not that it has no moisture content? I have a handbook number of 2.4 kg/dm^3 (that's 2.4 kg/liter.. compare to water at 1kg/liter). Concrete, along with
http://home.earthlink.net/~jimlux/radio/math/catenary.htm has some equations to get you started. -- Original Message -- From: <W2fca@cs.com> To: <towertalk@contesting.com> Sent: Friday, April 18, 200
which mounts behind the meter for $5 per month. I >recently had it installed in my home. They installed a new meter ground rod which changed my ground from 150 ohms to 65 ohms. In >talking to the in
Depending on how many wires and how much current, here are some alternatives: 1) Circular MIL type connectors. Kind of pricey if new, but available surplus from many places at lower prices. There's a
Maybe they just used a motor that can take the stall current forever? A standard permanent magnet motor will typically have a stall current that is around 3-4 times the nominal running current (altho
I'd be interested to know the basis of the "verticality" requirement... 1 part in 100 (about 1/2 degree) wouldn't appreciably change the loads at the base (1% using the "small angle approximation"),
1 the structures, Indeed, it looks like a standard industry spec. But I was wondering why they selected that? And, is it aimed at 50-150 foot towers or 1000 ft behemoths.. For all we know, the EIA st
You really, really need to talk to the local building dept or to a local structural engineer who knows your local rules. "chemical anchors" are really nifty, but there are all sorts of rules, etc. th
to before, Yes, but... There's more to a transmission line than just the velocity factor and characteristic impedance.. namely the loss. However, at 80m, the loss won't be too high with either one, a
are: what 75 the You're right.. everything's upside down (I had it the other way, it didn't look right at first, so I flipped it.. too early in the morning..) However, the conclusion is basically th
What are you bolting it to? If you're bolting it to something that has some stiffness (i.e. angle or channel iron/alum), then it can be pretty thin. .062 (1/16") might be fine... 1/8" is pretty stif
Wrap a few turns of wire through them and measure their inductance. That will tell you the AL factor (inductance/square root(turns)) (and by implication the permeability).. Measure at a few different
Contest the to next horizontal For an unguyed pole, the engineering has been done for you. Go buy a 65 ot 70 foot flagpole. http://www.flagpoles.com/ is the website for Concord Flagpoles and they ha
. Can any mechanical engineers out there explain I take a stab at it.. the design IS basically similar.. Differences that may or may not need consideration are: 1) The Yagi design program will probab
I just ran across the following QEX article on the ARRL web site: http://www.arrl.org/qex/1123.pdf It gives all the necessary design equations, etc. for unguyed towers. The article references an exce