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LOW PIM CABLE SUPPORT BRACKETS™
ConcealFab has found that the hardware used to secure RF components behind or below base station antennas is often a source of passive intermodulation (PIM) at cell sites. In many cases, this hardware is used to secure RF jumper cables to metal members near the antenna. To eliminate this source of PIM, ConcealFab has designed a family of low PIM mounting solutions for securing RF cables near base station antennas.
Heavy duty galvanized steel solution:
ConcealFab’s first solution utilizes a pair of heavy duty, galvanized steel brackets secured to the antenna mounting pipe using two 3/8” galvanized steel threaded rods. The all galvanized steel construction eliminates dissimilar metal contacts between the pipe and the brackets, which has been shown to generate PIM. The threaded rods maintain high clamping force between the brackets and the antenna mounting pipe as well as provide a convenient mounting location for plastic cable support blocks available from a variety of manufacturers. (Cable support blocks sold separately)
ConcealFab offers a small grip range option for securing two typical cable support blocks (four 1⁄2 inch jumper cables) and a large grip range option for securing up to six typical cable support blocks (twelve 1⁄2 inch jumper cables.)Longer threaded rods may be substituted in the field to secure stacks of larger diameter cables.
Plastic support base solution:
ConcealFab’s second solution utilizes a patent pending injection molded plastic support base secured to metal members near the antenna using 1/2-inch wide Deltec® cable ties from Thomas & Betts (or equivalent). This all plastic support system eliminates PIM producing metal-to-metal contacts between the cable support system and the antenna mounting pipe. The support base is produced from high strength, UV stable, glass filled nylon and the Deltec® cable ties are the produced from high strength, UV stable Acetal.
The support base includes internal features for securing a 3/8” stainless-steel hex-head bolt with oversized head. A shortbolt (1.25”) can be used to secure snap-in cable support hardware and a longer bolt (4”) can be used to secure multiple cable support blocks. (Hardware kits sold separately). Plastic snap-in cable supports should be used with this support system to prevent PIM.