Antennacraft ST4 User Manual
Outdoor Scanner-Ham
Discone Antenna
25-1300 MHz
Model
ST4
www.antennacraft.net
120307
Compact Design—
allows exibility when choosing an installation site
Low wind Resistance and Lightweight—
allows higher mast mounting
Resonator and Tunable Whip—
for best 50 MHz performance
Easy Assembly and Connection—
uses rugged stainless steel hardware, radiator rods,
and standard supplied SO-239 terminal and attaches
to PL-259 cable connector (not supplied)
This discone scanner and ham base station antenna is our most
efcient omni-directional antenna system, combining a disc antenna with electrically matched radiators. You can use it to receive and transmit a wide range of signals, including amateur
radio, aircraft and other special services, on your scanner or oth-
er receiver. The antenna is designed to provide high efciency
when receiving and transmitting signals on selected frequencies.
Your antenna receives VHF and UHF frequencies between
25 MHz and 1300 MHz (1.3 GHz), and transmits effectively at
50, 144, 220, 440, 900, and 1296 MHz. It handles a maximum
transmitting output power of 200 watts and provides a standing
wave ration (SWR) efciency of 1.5:1 or better over the receiving and transmitting spectrum. It is 44-inches high overall, and
ts on masts up to 1-1/2-inches in diameter.
BEFORE YOU BEGIN
Read this manual and the separate Consumer Product Safety
Committee “Safety Instructions”.
WARNING: When you start to install an antenna,
use extreme caution. If the antenna starts to fall, let it
go! It could contact overhead power lines. IF the antenna touches the power line, contact with the antenna,
mast, cable, or guy wires can cause electrocution and
death. Call the power company to remove the antenna.
DO NOT attempt to remove it yourself.
For your safety and convenience, plan each step of the installation. Organize the parts and check them against the following list.
You need a suitable length of RG-58 coaxial cable tted with a PL-259 connector at each end, mast mounting hardware, and a small wrench with a 5/16-inch
opening (not supplied).
1
ASSEMBLING THE ANTENNA
1. Install the two mount brackets on the support tube using one 8-32 x 1/2-inch screw, one #8 lockwasher and
one 8-32 nut for each bracket. Do not fully tighten it
yet.
2. Position one bracket at the midpoint of the tube. Position the other bracket at the bottom of the tube.
Support Tube
Mount Bracket
7. Screw one 8-32 nut onto the threaded end of each of
the eight cone assembly rods.
8. Screw each cone assembly rod into the base of the
cone section of the apex assembly, and hand tighten each rod. Next, use a wrench to tighten each nut
against the cone surface to secure each rod.
9. Insert the whip assembly into the top of the coil assembly.
10. Note: Never use a wrench on the black plastic insulator part of the apex assembly.
section of the antenna mast, and secure each bracket
with a U-bolt, two ½-inch split lockwashers, and two
1
/4-20 hex nuts. When each bracket is in the correct
position, tighten the nuts fully.
13. Use the appropriate mast mounting hardware (not
supplied) to secure the coaxial cable to the antenna
mast, leaving some slack in the cable. Mount the mast
section to your chosen mount, following and instructions that come with the mount.
14. Route the rest of the cable to your receiver or trans-
lengthen the antenna by loosening the set screw
and pulling the whip out of the coil about 1/8-inch.
If the SWR reading on the highest channel is higher
than that specied in the meter’s instructions, remove
the whip from the coil and cut 1/8-inch from its lower
end. You can cut the whip with a hacksaw or large
wire cutters. You can also use a le to make a small
groove around the whip and then break off the piece.
6. Measure the SWR again and repeat the adjustment, if
necessary. Cut off only 1/8-inch at a time, checking the
s/WR each time.
Nut
Lockwasher
Screw
3. Slide one end of the RG-58 coaxial cable with PL-259
connectors through the support tube. Connect the PL259 connector to the SO-239 terminal on the apex
assembly.
4. Install the apex assembly into the end of the support
tube and secure it with three 4-40 x 3/16 screws and
lockwashers.
5. Screw one 8-32 nut onto the threaded end of each of
the eight disc element rods.
6. Screw each disc element rod into the holes around
the upper disc of the apex assembly, and hand tight-
en each rod. Rotate each 8-32 nut until it ts snugly
against the disc. Then use a 5/16-inch wrench to tight-
en each nut against the disc surface to secure each
rod.
Nut
Apex
Assembly
SO-239
Terminal
PL-259 Connector
(not supplied)
Rod
Cone Assembly
Apex Coil
Assembly
Nut
Rod
11. To secure the whip assembly, use the (supplied) allen
wrench to tighten the set screw.
12. Place the two mounting brackets against the chosen
Whip Assembly
Allen Wrench
Support Tube
U-Bolt
Mast
Lockwasher
Nut
Bracket
mitter. Attach the supplied yellow Danger Label to the
mast at eye level, as a safety reminder.
TUNING THE ANTENNA
1. To ensure your antenna works with a minimum standing wave ration (SWR) on all channels in the 6-meter
amateur radio band, we allowed extra whip length for
proper tuning.
2. To properly tune your antenna, you need a SWR meter, available at your local electronics store.
3. Connect the SWR meter between the transceiver
and the antenna cable, as described in the meter’s
instructions.
4. Measure the SWR on the lowest and highest channels.
5. If the SWR reading on the lowest channel is high-
er than that specied in the meter’s instructions,
FREQUENCY CURVES
Support Tube
Lockwasher
Screw
3
2
Loading...