Assessments - 3, GPA: 3.3
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You’ll also need tools such as; ladders, electrical tape, waterproof sealant, a knife, wire cutters, etc. The first thing to do is to cut the antenna wire to the correct length. The wire supplied with your kit has been cut somewhat longer than required, but there is not enough for two antennas, so be careful when you measure! The following table shows you the proper lengths to cut your antenna wires in order to tune it to the proper frequency. Please understand that the calculations that we have made are for a frequency in the center of the band. If you prefer to use another frequency, or a band that is not listed, simply find the lengths by using the following equations. (It doesn’t hurt to add a foot or so to the calculated length to allow for easier antenna tuning - it’s easier to simply “clip” off a bit of wire at a time than it is to add wire.) Total length of a dipole = 468/ frequency (in MHz) (in feet) Page 8 RAMSEY DA SERIES DIPOLE ANTENNA Total length or an Inverted V = 445/ frequency (in MHz) (in feet) Your Frequency_________ Calculated Length___________ ANTENNA BAND FREQUENCY (KHz) NORMAL DIPOLE INVERTED V ALL BAND > 1850 129’3” 122’9” 160m 1850 129’3” 122’9” 80m 3750 63’9” 60’6” 40m 7050 33’11” 31’6” 20m 14250 16’9” 15’8” 10m 28500 8’5” 7’11” Antenna Wire Length (per side) NOTE: Measurements indicated for each side of dipole. RAMSEY DA SERIES DIPOLE ANTENNA Page 9 For example, to make a dipole antenna on 14.050 MHz, divide 468 by 14.05. The total dipole length be 33.31 feet or approximately 33 ‘4”. Don’t forget that you need to insert a feedline in the center, so it must be cut into two pieces that are one half the length (16 feet, eight inches). Wire Length (approximate length packed with indicated antenna kit) 160m or ALL BAND .................. 262’ 80m ............................................ 132’ 40m ............................................. 72’ 20m ............................................. 38’ 10m ............................................. 21’ 1 in. 1 in. Page 10 RAMSEY DA SERIES DIPOLE ANTENNA ASSEMBLING THE ANTENNA Start by finding three locations to attach your antenna. The center location must be close enough to your ham shack so that the coaxial cable will reach, but should also be as high as possible. Attaching it to a location on the roof, or to the chimney is a great place, as long as you are sure that the wires will not come into contact with trees, power lines (cringe!) or the house. Remember what that great ham, W2BOZO said, “If you touch a powerline with that antenna, you’re going to be one sad ham.” Kind of says is all, huh? Remember, the antenna wire is not insulated (and does not need to be). The two end locations should also be sufficient so that the antenna stays somewhat straight, and is a safe distance off of the ground. You should also make sure that they are sturdy enough. Ripping the aluminum drain piping off of the side of your house, or pulling your favorite night table out of your bedroom window by one of the legs not only earns you bad points with the spouse, but it can get expensive and dangerous quickly. The best items for this? A sturdy metal pole, tall fence pole, good sized tree, sturdy connection point on your house or garage, and almost any place that you can trust to hold the antenna under windy conditions. When you have found these spots, it is time to prepare the antenna. First, take one end of each of the wires, and place them on your workbench, or other suitable area with a high power soldering gun. Next, place one of the insulators in front of you on the table. Some manufacturers and ham radio dealers sell center insulators that have various mounting features. If you see 1/4 in. one that you feel would be well suited for this job, you may substitute it for the center insulator. Be aware, however, that many of them can be considerably more expensive to perform the same job as the one that you now have. RAMSEY DA SERIES DIPOLE ANTENNA Page 11 Taking the end of one of the wires, pass it through the hole in the insulator until six inches are through. Next, bend the wire back on itself and immediately begin to wrap it very snugly and neatly around itself. Ideally, you should have about six or seven turns. Using your soldering iron, heat up the wire turns and solder each of them until the wire is secured very tightly. This way, the loops take up most of the stress, but the solder keeps it from getting loose. Connect the other wire in the same manner. Make sure that you look over each connection thoroughly. Next, take the remaining two insulators and connect the wire to them using almost the same method. Pull 18 inches through the hole before securing it. Don’t forget to leave a 1 inch loop! The extra wire allows you to trim the wire easily, while the extra wire acts as part of the antenna length. Six inches are used up at each end of the wire to secure it, and the other foot is used here to hang down for easy tuning. Now it is time to connect...