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"Pierre Vachon" wrote Hi there, I am trying to build a longwire antenna for use in the 20 meter band to 70 meter band area. I was looking for advice on what materials to use for the antenna and the lead in lines. I will hook it up to a Drake r8B radio. What is the minimum height it has to be? Where to ground it?. Actually, does it have to be grounded if the radio is grounded at the outlet? I am a little limited in space as my yard is only 75 feet long and there are power lines at the front. I assume that they are the source of an irritating hum on the receiver on certain frequencies. Thanks for the help in advance. Pierre The minimum height above ground is about 1 millimeter ;-) That's where Hurricane Isabel dumped one of my long wires last fall. It took over a week to clear debris away before I could get it back up in the tree it was pulled out of. It still received quite well in the meantime, even laying on the ground. Of course the higher the antenna, the better it receives. At an angle of more than 45 degrees, there is very little effect on the direction the sloping wire points. At an angle of more than about 75 degrees, you are approaching a "vertical" which is known for it's higher background noise. Not desirable in DX work. You didn't say if you are going to use a Balun transformer at the antenna and coax feedline to connect to the radio. *If* you do, then you can certainly ground the shield of the coax at the balun (even ground the unused side of the balun), and shield ground the coax again before it comes into your home. That can certainly help reduce noise. If the coax shield is not grounded, the home electrical ground can "feed" noise from the radio, out the coax shield, and back into the coax center conductor at the antenna connection. Shield grounding does prevent this from happening. It is also required in order for any static or lightning protection device to work properly, should you use those devices. Good luck, Jack |
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