Monday, 2 November 2009

Tower 7 (M7) - RADIO ARCALA MAMMOTH 160/80M BEAM IN A NUTSHELL

RADIO ARCALA MAMMOTH 160/80M BEAM IN A NUTSHELL
If you want to build an Arcala Extremes (OH8X) style beam, you should start with measuring your property lines. Each of the four guy wires extends 120 meters or 400 ft from the tower – representing an area of 170´170 meters (550´550 ft) for a needed total space of almost three hectares. And then be ready to order needed 450 meters (1500 ft) of heavy duty tower sections. And finally make it look nice with 600 litres (120 gallons) of paint! Ready for the latest story from frozen Arcala deep North?


Height and weight of the system
Tower height 100 m (330 ft)
80 m beam 90 m (300 ft)
160 m beam 80 m (270 ft)
Total weight 39 600 kg (80 000 lbs)

Elements, gain and take off angles
160 m 3 elements, 12.9dBi,
26°80 m 5 elements, 15.7dBi, 12°

FronttoBack ratio

160 m 20-30 dB
80 m 20 dB

Operating frequencies
1810-1845, 1845-1880 kHz (SWR <>
3500-3560 kHz (Lmatch)
3700-3800 kHz (50 ohm / current balun)

160 m elements
Weight 1600 kg, (3800 lbs), each
Length 59 m (190 ft), all elements 12m (36ft) capacitive hats
Each use 700 m (2100 ft) of tubing
Tuned with 06 μH coils at the centre
Relayswitches for turning the ant 180°

80 m elements
Length 46 m (140 ft), longest
10 m from the 160 m antenna
max windload, 70 m/s.

Boom dimensions
160 m length 71 m (215 ft)
80 m length 60 m (200 ft)
The triangular 160m boom (2.2 m, 7.3 ft) comes with a rail for walking inside it.
Turning gear
Weight 2000 kg (6000 lbs)
11 kW motor
Inverter driven softstart/stop
Largest guy ring bearing
Weigth 3300 kg50 mm (2”) diameter balls in the bearing arrangement
Ring diameter 3,8m (13 ft)
Guy wires
Total length 2300 m (6900 ft)
Phillystran/element guys 1150 m (3450 ft)
Final touch
600 litres (120 gallons) of paint

Mechanical design and project Management
Tuomo Halminen,
HALTA OY

Antenna design
Pekka, OH1TV, 160 m
Olavi, OH5BR, 80 m
Lauri, OH8LK,
switching systems
Arcala team members busy at the project
Juha-OH8N
CVeijo-OH6KN
Martti-OH2BH
Toni-OH2UA
Group working on the project of their lifetime
Toke, OH6RMPekka, OH7RMMarkku, OH8SR.

The construction is capable of handling ICE and SNOW for its own weight. In an ice storm? God Bless Radio Arcala!

Scalebarfor the tower base, Juha OH8NC, who restored Mammoths to Arcala.


Martti, OH2BH and the rotator gearbox.


160m element-to-boom joint and another scale bar.

Arcala 60 meter sprint track. 65°11’N, 26°9’E and 220 m above sea level.

Finnish antenna workers are powered by Perkele. Pekka OH7RM up in the fog.

Arcala Engineering Team at LC works; Juha, OH8NC; Lauri, OH8LK; Pekka, OH1TV; Olavi, OH5BR and Toni, OH2UA.

These guys were breaking snow and ice when getting the Arcala Mammoth up infreezing, stormy weather... often high up at 100 meters battling subzero temperatures days in and days out.Hats off to Markku, OH8SR (left), Toke, OH6RM and Pekka, OH7RM.
Truly, these are men of iron!