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ACOM LS108 HF Log-periodic Antenna 

Align the three riveting holes and insert a rivet in each hole, without riveting. Arrange the whole half-element 
in this manner for a test only, without riveting for now. Check the total half-element length per 

Table 1 - Half-

Element Lengths. 

If you find any discrepancy, correct the mistake prior to continuing. This check will ensure 

possible mistakes are avoided that could necessitate un-riveting multiple sections at any later stage. 

 

Table 1 - Half-Element Lengths. 

Element N

о

.       

 

 

1

2

3

4

5

6

7

8

9

10

Half-length, m: 

5,51

4,98

4,45

3,99

3,57

3,20

2,86

2,56

2,29

2,05

(ft): 18,1

16,3

14,6

13,1

11,7

10,5

9,4

8,4

7,5

6,7

 

 
After passing the arrangement test, disassemble the half-element. Lightly smear the contact surface of the 
smaller-size section with conductive paste (supplied with antenna). This will ensure corrosion-free electrical 
contact between the element sections. Insert the smaller-size section into the next one at a distance of about 
100 mm (4”) and align the three riveting holes again. Insert a rivet (4 x 8 mm) in each hole. Begin riveting 
them one-by-one, without removing the others out of their places. Support the free rivets in order to keep 
them in place during riveting. This is important since the tubes could come out of position otherwise. 
 
Use the "Hand Blind Riveter" tool, which is supplied with antenna, together with the needed number of rivets 
(there is a reasonable reserve). Operation instructions about this tool appear on its original packaging. 
 
Proceed similarly to assemble the remaining eighth half-element pairs. 
 
2.3.  Mounting the Elements to Boom 
 
All element-supporting insulator blocks are factory mounted on the boom sections. They isolate between 
half-elements as well as from each half-element to the boom.  
 
The large ends of the completed half-elements are to be mounted on the supporting insulators at the same 
time. All the required hardware and mounting tools are bagged in polyethylene envelopes. 

 

Please look at 

Fig. 4 Elements mounting

. Start with the longest element (ELEMENT 1). The left half-

element is marked with “1L” and the right one - with “1R”. The insulator has two channels for element 
installation. They have the same marking “1L” and “1R”. Lay the two half-elements in the corresponding 
channels. 
 
Select two bolts M5x60 mm and place a plain (flat) washer on each bolt. Align the mount holes of the half-
elements and the insulator. Push the two bolts upside-down through insulator and half-elements. Use the 
holes located next to the boom. Please note that the bolts heads are underside of insulator as shown in 

Fig. 

4 Elements mounting

. Smear a small amount of conductive paste on the tubes as pointed in the figure. 

Push an M5x45 mm bolt with a plain washer through the next holes that are more distanced from boom. 
Secure with lock washers and nuts on top of the tubes. Tighten the joint well but without deforming the tubes.  
 
Mount the next elements – ELEMENT 2 t

о

 ELEMENT 4 on their insulators in the same way.  

The rest antenna elements (ELEMENT 5 to ELEMENT 10) should be installed in the same way but you 
should use shorter bolts in the holes next to the boom - M5x55 mm. Refer to 

Fig. 4 Elements mounting.

 

 

2.4.  Attachment of Phase-line Straps 
 
The distribution (phase) line feeds each antenna element in the center. It comprises nine pairs of straps 
(called phase-line straps hereafter) that cross-connect in pairs between adjacent elements. Each phase-line 
strap has a mount hole drilled at each end. 
 
Locate phase-line straps and arrange them in pairs according to length. Now look at 

Fig. 5 Phase-line 

straps mounting. 

Start mounting the longest strap pair between the longest antenna elements (ELEMENT 1 

and ELEMENT 2). Place four plain washers on the four bolts of ELEMENT 1 and ELEMENT 2 that are closer 
to the boom. Smear these bolts and the strap ends (on the two surfaces) with conductive paste. Attach one 
end of the straps on the smeared bolts of ELEMENT 1. Cross the straps above the boom so that their free 
ends reach the smeared bolts of the opposite ELEMENT 2. Place a plain washer, lock washer, and a nut on 
ELEMENT 1 bolts only.

 

Do not fully tighten at this time. 

 
The second-length straps should be installed between the inner bolts of ELEMENT 2 and ELEMENT 3 in a 
similar way. Remember to smear the straps with conductive paste on the two surfaces. Now place a plain 
washer, lock washer, and a nut on the bolts of ELEMENT 2. Do not tighten the nuts yet. 

 

1mm=39.37mil 1cm=10mm=0.3937” 1m=100cm=3.281ft 1kg=2.205lbs 1m =10.764sq.ft 

1km/h=0.62137mph

 

3

2

Содержание LS 108

Страница 1: ...ASSEMBLING MANUAL LS 108 HF Log Periodic Antenna 14 30 MHz ...

Страница 2: ...30 МHz continuously Gain average 9 5 dBi Front to Back Ratio 20 dB Nominal Input Impedance 50 Ohm SWR typ 1 5 1 Maximum Input Power 1500 W continuously 3000 W PEP Boom Length 8 m 26 25 ft Boom Diameter 50 mm 1 97 Mast Diameter 50 mm 1 97 Longest Element 11 m 36 1 ft Turning Radius 6 8 m 22 3 ft Wind load Area 1 5 m2 16 15 sq ft Wind Survival no ice 145 km h 90 0 mph Weight Operating 30 kg 67 lbs S...

Страница 3: ...r 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 r...

Страница 4: ...nstallation They have the same marking 1L and 1R Lay the two half elements in the corresponding channels Select two bolts M5x60 mm and place a plain flat washer on each bolt Align the mount holes of the half elements and the insulator Push the two bolts upside down through insulator and half elements Use the holes located next to the boom Please note that the bolts heads are underside of insulator...

Страница 5: ...arest strap insulating spacer located between ELEMENT 10 and ELEMENT 9 Together with the cable fasten also the legs skirts on the two strap spacer sides see Fig 5 Phase line straps mounting Continue fastening the cable with two ties at each spacer until you reach the mast Now fasten also the strap insulating spacers in the other part of the boom although there is no cable there 2 6 Boom to Mast As...

Страница 6: ...sulator and get the element horizontal Now tighten properly all the nuts that hold the phase line remember the caution note in S 2 4 Attachment of Phase line Straps Do not over tight Check all antenna dimensions per Table 1 Half Element Lengths and Fig 9 LS108 Dimensional Drawing before to start lifting the antenna on your permanent tower structure Check the quality of all mechanical and electrica...

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