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moisture. A time domain reflectometer can be used to locate kinks and bends or to verify that they do not exist. Kept as a permanent record, they can be com- pared at each future tower/transmission line inspectin. Cathodic Protection As you may be aware, since OSHA has issued an advisory, several towers across the United States have fallen down because of underground corrosion of their guy anchors. The corrosion usually takes place where the guy anchors enter the concrete block, approximately ten feet below the surface. There is no way to reverse the underground deterioration which is taking place, but it can be stopped through the application of cathodic protection. Adding a cathodic protection system is easily accomplished by a trained crew when they are on site. Usually this requires removal of any copper ground rods which are installed adjacent to the anchor. These ground rods are replaced by galvanized ground rods, which incidentally are required in order to be in compliance with the new ANSI T1.313-1991 specification. The cathodic protection system should be measured each year to assure it is still doing its job, but requires no other maintenance. Site Grounding The existing site ground resistance can be measured in addition to determining the apparent effectiveness of the above ground connection to the ground system below ground. While the reliability aspects or condition of any mechanical clamp or connector used below ground cannot be determined, the effectiveness of the mechanical connection can be reasonably determined by measurement of loop resistance. Examination of other site equipment including fence and gate grounding can be done while on premises. Recommendations to lower existing ground resistance to a more desirable value can be provided after the site visit, if requested. |
Space Inventory, etc. During any site visit, the proposed space for new digital or analog RF and muliplex installation can be evaluated in terms of access to DC power, waveguide routing from building entrance, access to the nearest master or intermediate ground bar and typical physical problems associated with a "hot cutover." Conclusion This article has discussed the many issues involved in your move from the 2 GHz to the 6.5 GHz frequency band. The first step is a thorough site inspection and evaluation to determine which of your existing equip- ment is suitable for reuse at the higher frequency. Andrew offers this site inspection service and is highly qualified to provide you with an expert evaluation and recommendation. In addition, Andrew can provide all of the required site improvement equipment and services. |