At 04:20 PM 4/10/05, you wrote: >Hi all > Does anyone know if a dual band antenna for 144/220 is available. . >If so who makes it? >Thanks in advance >Mike
Mobile, base or mountaintop repeater (i.e. bad weather) ? Mobile, well, take your pick. Base, look at Diamond or Comet, but use some of the self-gluing heat shrink (CATV style) around the joints. Do a web search at www.repeater-builder.com (the search function is just above the main menu) for CANUSA. Repeater - there is only one decent dual band commercial grade antenna that I have found, and it's a compromise... the DB 314 is essentially a 8 UHF dipoles (a DB-408, 6.6db gain) and 4 high band dipoles (half of a DB-304, 3.2db) on the same mast, made with separate harnesses. You can use separate feedlines or a TX-RX commercial grade diplexer and one feedline. I ran into the DB314 a number of years ago at a mountaintop site where the site rental specified one rack cabinet space (four 1'x1' tiles) and a single space on the tower. The system was a UHF repeater, a 2m remote base, a 420mhz point-to-point link to another mountaintop, and a 420mhz autopatch link down to the ground. The DB314 was ordered by the system owner and used as separate 2m and 440 antennas with two feedlines. The factory mast was not used and was replaced with a longer one that held the DB314 plus the four 420mhz end-mount beams. The cabinet was two Moto "J" cabinets, one with the top cut out, the other with the bottom cut out, stacked and welded together by an auto body shop, and painted Chevy Malibu white (they were repairing three local police cars that week, and used some leftover paint). The duplexers, isolators & pass cavities and 2m DCI filter were in the top 2/3 of the upper cabinet, the radio equipment in the remaining space. The owner commented 6 months later that the 2m performance was not what he expected due to the half-size 2m array and if he had to do it over again he would have bought a DB408 and a DB204, made up a longer mast on his own, and stacked them plus the 420mhz beams. Note that the DB314 is a tall antenna to start with, if you roll your own by putting a 408 and a 204 on your own mast it's going to be even longer. This is definitely a side-mount-only array.... any normal mast will fold over if you bottom mount it and a good wind shows up. Here's the DB314 data sheet: <http://www.repeater-builder.com/db/db-314.pdf> The DB314 or the 408/204 combination is NOT cheap, but quality antennas never are. You can, however, plan on amortizing it over 20+ years. How many Diamonds or Comets would you have bought over that time period? And if the site owner requires a professional rigger to climb the tower for anything you have to figure that cost in also. All in all, for the same mountaintop service life the commercial grade antennas are cheaper than the Diamonds / Comets. 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/
