Back to antennas...
I have a Diamond Duoband vertical side mounted on the tower
http://www.rogerhalstead.com/ham_files/Tower26.htm that is used mainly for
near by repeaters and simplex to mobiles. I have a small antenna (not
visible in the photo) at roughly the roof line for the local repeater and a
second Diamond at the roof line on the far side of the shop (partially
visible if you know where to look) I want to add a second to the tower that
will be used for digital in the 145 MHz range with a minimum of interaction.
There is heavily wooded low ridge line about a 100 yards to the West of my
back yard which puts even the side mounted vertical well down into the trees
when going West or SW.
I'm probably going to raise the current antenna about 10 feet, but that is
about as close as I dare get to the TV antennas at roughly 90 feet. Those TV
antennas have remote preamps and it takes traps to keep out the 2-meter
signals which are between the high and low VHF bands. I'd really like to
put the second duobander right up on top of the mast, but with the lightning
track record around here, antennas mounted up there would probably have a
very high mortality rate.
I would guess mounting another on the opposite side of the tower would be a
worst case with the most interaction. That leaves mounting the second one,
either upside down (base to base) with the existing one, or side mount them
with one immediately above the other. (top to base with no more than 2 or 3
feet of separation).
Also note the stacked beams on both 144 and 440 bands at the top of the
The reasoning behind this addition is a voice link on 440 to the NWS
(usually takes the beams), remote station control as well as cross band
receive on 440 and digital (both packet and as an Internet gateway routed to
other ham gateways, the NWS and the local EOC)
Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
TowerTalk mailing list