Listen Technologies LA-140 - Manual (Page 11)

Mounting
Mount the antenna in a strategic location. Your antenna may be placed either
indoors or outdoors. If mounted outside, the highest elevation should not exceed
100 feet (30.5 m). The antenna should be placed in a location that will provide
the best line of sight to the receivers. Keep in mind that the higher you have the
LA-107 mounted, the more range you will get out of your receivers.
The LA-107 includes a bracket that allows it to be mast
mounted (vertical pole) up to 1.5 inches (4 cm) in diameter.
This pole can be made of metal or plastic. However, if using
a metal mast, the LA-107 should be isolated from the ground.
It is very important that your mast does not extend above the
antenna radiator. This will create interference and multi-path
to the receiver.
Mount LA-107 away from power lines, telephone lines and
metal surfaces.
For maximum range, your transmitter should be set to “High”
RF power.
Run the coaxial cable from the antenna to your device,
keeping the cable length as short as possible (see page 4,
Shortening the Coaxial Cable if necessary). To optimize the
efficiency of the LA-107, or to extend the length of your cable
run, RG-8 can be used in place of RG-58.
mast
WRONG
mast end
CORRECT
Mounting Your LA-107