Model 18AVQII
Five Band Vertical Antenna
10, 15, 20, 40, 80 Meter
308 Industrial Park Road
Starkville, MS 39759
(662) 323-9538 Fax: (662) 323-5803
INSTRUCTION MANUAL
General Description
The Hy-Gain 18AVQII is an omni-directional, vertical radiator that operates on the 10,
15, 20, 40, and 80 meter amateur bands. The system will work against earth ground or a
resonant radial system when mounted above ground. You can make your own radial
system following the manual, or use the Hy-Gain 14RMQ Radial System Kit available at
your Hy-Gain dealer.
The antenna can be used for either Phone or CW with either a ground or roof mount. It
can also be tuned to mid-band for use with either Phone or CW. In either case, the SWR
bandwidths of the antenna are broad enough that the antenna will operate at an SWR of
2:1 or less on the 10, 15, 20, and 40 meter bands. The antenna will radiate on the 80
meter band with a limited bandwidth. The 18AVQII is supplied with stainless steel
hardware and element clamps for all electrical and most mechanical connections.
Theory of Operation
The use of heavy duty "Hy-Q Traps" provides automatic band selection. The Hy-Q Traps
are parallel resonant circuits which isolate the various sections of the antenna and give
quarter wavelength resonance on all bands. The top loading coil is used for operation on
the 80 meter band while the overall height of the antenna remains less than 20 feet.
WARNING:
When installing your antenna, take extreme care to avoid any accidental
contact with power lines or overhead obstructions. Failure to exercise this care could
result in serious or fatal injury.
NOTE:
If the terminals of the input connector are checked with an ohmmeter, they will
show a direct short. This is normal! The matching coil in the antenna base puts the entire
system at DC ground, but presents a 50 ohm load impedance to RF energy.
Choosing a Site
The 18AVQII can be mounted on the ground, on a rooftop, or on a mast.
The antenna
should be secured using non-conducting guy ropes if the 80 meter loading coil is
installed. When choosing an installation site be sure to allow sufficient space for these
guy ropes.
