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Cal-Av Labs 2D-40A User Manual
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Revised 14 June 2003 1USER MANUAL / ASSEMBLY INSTRUCTIONSCAL-AV Labs, Inc. 2D-40ADUAL-DRIVEN ELEMENT 40 METER ANTENNADESCRIPTION:The 2D-40A is a rotatable horizontal array of two full-size, closely spaced drivenelements. Each element is about 70 feet long. The rear element is longer than the front.They are fed approximately 140 degrees out of phase, using a shielded phasing line thatis inside the boom. The pattern is cardioid, with a free space forward gain of 6.5 dBiand a front-to-rear ratio of 20dB.Matching and fine tuning is by means of hairpin transmission lines mounted along theunderside of the boom near the feed point of each element. Both hairpins are adjustable.The front hairpin is used to set minimum VSWR, which is specified as adjustable to 1.0:1anywhere in the entire band. Adjustable element tip lengths set the intended operatingfrequency of the array. It is noteworthy that all four element tips are moved by the sameamount for a frequency adjustment. The rear hairpin adjusts resonant frequency over asmall range, approximately 70 kHz.Feed connection is by means of an SO-239 UHF receptacle located in the RF neutralsection of the forward hairpin. This patented feed, phasing, and matching system alsofunctions as a wide band, high power balun. Also, because the elements are electricallyconnected to the boom at the neutral points of the hairpin sections, both a static drainand a dc path for lightning-induced EMP or direct-strike current are provided.In no-ice conditions, wind survival is 100 mph. With 1/2 inch of ice loading on theelements, the wind survival is de-rated to 40 mph. Weight of the 2D-40A, includinghardware, mounting, and matching accessories, is 163 pounds (74.1 kg). For moredetailed information, including specifications, drawings, parts list, patterns and graphs,please see the appendices.UNPACKING:The 2D-40A is shipped in three cartons; two are about 7 feet long, and the third is abouta 2-foot square.Inspect cartons for any sign of shipping damage. Then open cartons and inspect thecontents for hidden damage. Shipping damage is not a common occurrence, but it doeshappen. If damage is found, save the cartons and packing materials, and notify thecarrier.Remove contents and inventory for the following:Carton 1:1 of each of the following: Front, rear, boom and mast mounting plates1 kit Mounting plate hardware. |
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