DB makes the DB-314, essentially a 8 UHF dipoles (6.6db gain) and 4 high band dipoles (3db gain) on the same mast, with separate feedlines. Add a TX-RX diplexer (the model made for tower-top use) and you've got a commercial-spec dual band antenna. Install it properly and you can ignore it for 20 years.
Spec sheet at <http://www.repeater-builder.com/db/db-314.pdf> Or if you have someone good with a welder you can make your own. <http://www.repeater-builder.com/antenna/440fdipl.pdf> shows you how, and for the 2m side use <http://www.repeater-builder.com/db/db-224e-diagram-dz.pdf> and for the 440 side use <http://www.repeater-builder.com/db/db-404-b-diagram.pdf> but note that the measurements on the last diagram are for a 450-470 antenna. Further comments in the text below. At 04:32 AM 1/29/06, Kris Kirby, KE4AHR <[EMAIL PROTECTED]> wrote: >On Sat, 28 Jan 2006, Jim Connell, KH6JKG wrote: > > I have a preference for Station Master antennas. But you get duplex noise after a while, especially if you don't side mount it with a top brace. See <http://www.repeater-builder.com/antenna/cracking.html>. All of the above articles are referenced from the web page at <http://www.repeater-builder.com/rbtip/ant-sys-index.html> > > Although, most of our > > sites are simulacasting on VHF & UHF. So, dual-band antennas where also > > used over the years. > >You may be able to hack around this if you can get permission to install >another antenna below your current antenna. Then get a diplexer, place it >up the tower and mount the other band's super stationmaster upside-down >below the primary one. You'll have to see about water drainage issues, of >course. And you may have to order the lower antenna specifically for inverted mounting. Yes, you can get them that way. > > On the sites with unused parts of these dual-band antennas, should the > > unused section of the antenna be terminated? With a short or 50 ohm > > termination? > >Seems preferable to do so as some sites have reported interference issues >from unterminated coax in the building attached to antennas on the tower >no longer in use. True. And cell-site surplus 5w and 10w 50 ohm loads are frequently on eBay fairly cheap. I saw a pack of ten 10w N-male loads go for $40 about a year ago. Add a double N female adapter to one of those and you have an instant feedline terminator. Mike WA6ILQ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
