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Cure of thermosetting resin is initiated by heat in the die and catalyst in the resin mix. The rate of reaction is controlled by heating and cooling zones in the die. The resulting high strength profile is cut to length, ready to use as it leaves the pultrusion machine. The controversy over metal versus fiberglass antennas continues, despite the over whelming evidence in favor of fiberglass. This article summarizes the contents of a number of other separate articles which have appeared in the industry media from time to time and is intended, from an objective point of view, to add credence to our claim that fiberglass is better. The ipso facto use of fiberglass, of course, does not guarantee a good antenna and there are a few antenna manufacturers who have "missed the boat" on techniques, which means there are poor quality fiberglass antennas, just as there are poor quality metal antennas, out there. Our company carries the entire line of Mart products, including their world-famous lines of high-power remote RF coaxial switches (up to 11 position!), quad antennas (UHF through 80 METER BAND!), antenna parts (such as spider hubs), heavy duty gin poles, tower insulators (insulates ENTIRE TOWER from ground), rotating side mounts, custom "H" frames, and much, much more. We now present the entire Mart catalog on-line! The catalog and linked pages offer current pricing, as well as many drawings, illustrations, and photos. NOTE....many Mart products are now IN STOCK, AVAILABLE FOR IMMEDIATE SHIPMENT! No need to wait for custom fabrication for many product classes. (Inquire) If you have any of these types of items to sell, (vacuum variable capacitors, vacuum relays, "doorknob" capacitors, variable inductors, or transmitting tubes ), either new, or good used stock, please state description, condition, and price by email or post. Both constructions use the same type of material, basically a thermoset FRP (fiberglass reinforced plastic), which includes specially formulated resins, flame retardants and UV stabilizers to produce the unique benefits which characterize fiberglass reflectors. Because some antenna installations must exist in environments containing many corrosive agents, the materials in the construction of the antenna must be carefully selected to alleviate corrosion problems. Obviously, in the case of an aluminum structure, dissimilar metal contact is always a risk factor. A fiberglass dish, on the other hand, all but eliminates this problem - for obvious reasons. The resins used in antennas have been subjected to both field and laboratory tests involving over 130 highly corrosive chemicals at temperatures up to at least 120° F (50° C), with results that indicated little or no detectable degradation of the test samples.
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