Cort, The problems most people have with colinears in radomes is (1) leakage of water into antennas assembled from more than one section, (2) internal connections which break or develop intermittents, and (3) they're often completely destroyed in a lightning strike, sometimes spectacularly, because the small-diamater conductors vaporize inside the sealed radome, causing an explosion.
(1) Can be addressed by using antennas with one-piece radomes. In theory, the right preparation to seal junctions might also work. In long-term installations, the gel-coat on the radomes will break down under UV radiation from the sun, followed by the fiberglass, which may allow water migration through the radome. (2) Broken internal connections can develop quickly if a fiberglass radome antenna is top-mounted on a tower. If it's side-mounted, with a brace for the top to stop waving in the wind, they can last much longer. (3) Some people swear by various lightning arrestor or static-dissipation schemes. I have no personal experience here. Others just put up a heavy-duty exposed-dipole array, which can often live through direct lightning hits with only cosmetic damage. Some people have good luck with Diamond or Comet, especially at sites with low potential for intermod. 73, Paul, AE4KR ----- Original Message ----- From: Cort Buffington To: Repeater-Builder@yahoogroups.com Sent: Thursday, March 13, 2008 1:36 PM Subject: [Repeater-Builder] Dual-Band Repeater Antenna Folks, I've been doing TONS of reading. Mostly I'm hearing that fiberglass radome antennas aren't so good in repeater service. I'm looking for a dual-band antenna (2m/70cm) for a 70cm repeater and 2m remote base. I'm not finding much that isn't a fiberglass radome. I'm not set on a huge antenna -- moderate gain would be fine. Any suggestions before I just say forget about it and just put up a DB-408 or DB-420 for the repeater and run the remote base on something 25' up the tower? 73 DE N0MJS
