ACOM LS108 HF Log-periodic Antenna
1.5. Location
The antenna should be mounted on a support tower structure at a height between 10 and 15 meters (33-50
ft) above the ground level. It must be located in the clear, away from trees, power installations, buildings,
other antennas etc. Such objects can be dangerous and they can reduce the antenna efficiency or cause
interference. If metal guy wires are used for the tower, they should be broken electrically with strain
insulators, at 2 meters (6 ft) apart or less.
1.6. Your first steps
The first step to installation is to fully read this manual. Then, carefully inspect the shipping cartons for any
physical damage. ACOM ships antennas in highly protected containers, but it cannot assure that
mistreatment by shippers will not occur. If there is any such damage, notify your ACOM dealer immediately.
Failure to do so may invalidate your warranty.
Select a large and clear area (10 x 11 m or 33 x 36 ft minimum) to assemble the antenna. Provide some
supports for holding the boom at a suitable working height.
The ACOM production uses metric (European) system of measurement units. The antenna elements (two
halves) and the phase-line straps are placed in separate polyethylene sleeves, marked respectively. The
hardware is bagged by size (there are some spares). A set of required tools to do the job is enclosed, too.
2. ASSEMBLING
The antenna comprises the following main components: boom, mast, ten elements, balun transformer, and
phase line (called also distribution feeder). The set includes also guys, installation elements, hardware, as
well as required tools.
An overall view of the antenna is shown in
Fig. 1
LS108 - Appearance
. All the ten elements are isolated-
mounted on the boom by ten supporting insulator blocks and each element is driven by the phase line.
2.1. Boom Assembly
The boom is composed of four pieces (sections), which are to be assembled together. The section ends to
be joined together are marked by letters A-A, B-B and C-C directly on the tubes. Sections have the element-
supporting insulators, mast bracket, balun transformer, and the boom guys readily installed in the factory.
You will find the required hardware situated along the boom sections.
Locate the four boom sections. Put them in order and orient letter markings so that “A” faces “A”, “B” faces
“B” and “C” faces “C” as shown in
Fig. 2 Boom Assembly.
Join together the sections marked A-A. Align the mount-hole pairs. Insert 2 bolts M6x60 mm through the
holes. Place a lock washer on each free bolt end. Screw in a nut on each bolt and tighten properly but
without losing the tubes shape.
Fit the other boom joints (B-B and C-C) together similarly. This completes the boom assembly.
2.2. Element Assembly
Each antenna element has two symmetrical halves, called half-elements hereafter. They consist of sections,
which are partly assembled in the factory to the longest suitable transportation length. The customer should
do the final assembly as described below.
For transportation, the element sections are bundled up in pairs and packed each element in a separate
polyethylene sleeve. The polyethylene sleeves are marked as follows: ELEMENT 1, ELEMENT 2, etc to
ELEMENT 10.
Note:
The shortest half-elements (number 10) are fully assembled in the factory.
Locate all polyethylene sleeves and identify them before to start assembling. Do not take out sections of
more than one sleeve at a time to avoid mixing up of sizes and lengths.
Begin with ELEMENT 1. Put all sections in the size order. Insert the smallest-size section into the next one at
a distance of about 100 mm (4”) - see
Fig. 3 Element Riveting
.
1mm=39.37mil 1cm=10mm=0.3937” 1m=100cm=3.281ft 1kg=2.205lbs 1m =10.764sq.ft
1km/h=0.62137mph
2
2
