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![]() Richard Clark wrote: On 21 Dec 2004 11:16:16 -0800, wrote: No, the tv tower is already up. I meant I can weld the elements. (Of course only if it is weldable material.) I was wondering if emt tubing would be a good choice? Hi OM, The consensus is that it is not. If you are going to invest your time and effort, short-cuts generally lead to repetition. You wanted to do this once? You are in the wrong hobby. Better is how to plan doing it many times, but planning to do it in the least stressful way. It is not I want to only do this once. It is I am a little scared of heights and do not want to climb up that tower any more than I have to. The antenna would be about 25 feet up. You had a range requirement of upwards to 70 miles. With a 25 foot elevation, your mileage range is roughly the square root of twice that - or 7 miles. You can double that if the other antenna is up equally far. If you are on a rise of land above the mean level, add that to your elevation. If the antenna at the other end is much higher, compute its range (hopefully a mountain top). It is a repeater 80 miles away I would like to hit. I would also to try long range simplex if possible. I had someone else tell me that a j pole does not work very well. Is this true? Varies by user as it is susceptible to transmission line length problems. These problems are SWR related. However, that aside, as a principle antenna for the range you ask, then that antenna at the other end has to make up for a lot (it better be higher, an array, or some combination). The other problem is the transmision line will have to be long, probably35 feet or more. Is this a problem? I can rotate the mast by turning the antenna rotor hooked to my tv down stairs. The only pain would be running down stairs every time I want to do it. You have to now investigate if your tower/rotator can in fact stand the additional wind load factor (or weight, or moment). What would you do in this situation? Can you get as good as or better performance building one yourself? Depends on your resources. It already sounds like you are shy there in finding aluminum of the proper grade. Best advice is to visit a metal scrap yard in the crummy part of town. Or - bite the bullet and pull out your wallet. If all this is to hit a repeater, and a popular one, you should simply try it and see what happens with a rubber duck. Then build a simple ground plane ($5) and hoist it as high as you can (on a broomstick out the 2nd floor window will do as a test). Popular repeaters are popular because they solved all these problems for you (by being high and having gain). 73's Richard Clark, KB7QHC |
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