Use a DB-408 the mast is the same size top & bottom. Hang it right side up from the top. You'll most likely be happier with the 408. The beam with is fatter. It will fill in holes in your coverage area better. The 420 has 3 dB more gain, however this will just help a little way out & hurt your middle ranges.
Fred N4GER -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Dave Baughn Sent: Tuesday, March 06, 2007 4:45 PM To: [email protected] Subject: Re: [Repeater-Builder] Antenna Mounting Question All of the DB dipole (loop) antennas I have seen have holes near the bottom of the loop for water to escape. I don't know why you couldn't mount the antenna upside-down and drill new holes near the new bottom. You might also inspect the rest of the antenna to see if there is anywhere that it may collect water when mounted inverted. These antennas are not normally designed for any beam tilt or null fill so the radiation pattern should be fine. Dave Baughn Director of Engineering The University of Alabama Center for Public Television and Radio WVUA/WUOA-TV & WUAL/ WQPR/ WAPR FM Box 870150 195 Reese Phifer Hall, 901 University Blvd. Tuscaloosa, Alabama 35487 205.348.8622 cell 205.310.8798 NEW EMAIL [EMAIL PROTECTED] >>> "Jamey Wright" <[EMAIL PROTECTED]> 3/6/2007 4:06 PM >>> I'm sure this has been covered here before but I'll ask again. I have the opportunity to place a repeater at a very good site. I can probably get an antenna at the 250 ft mark on the tower. The repeater would be in the 444.xxx range so I was looking at using either a DB408 or a DB420. The catch is that there is already a DB224 on that same mount so I was thinking I could invert my 2 choices for an antenna hang it from the bottom of the bracket. The mount is a 6 Ft sidearm on a Rohn 80 tower so it is beefy enough to handle the 2nd antenna. My question is this: Will inverting the antenna create any pattern problems or send all of my signal into the ground? Thanks for the input. Jamey Wright KD4SIY
