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Prior to hoisting ensure all equipment to be used, such as ropes, pulley blocks and hoisting grips are fit for purpose and in a fully serviceable condition.

Install the connector for the top end of the waveguide before hoisting. It is much easier to do this at ground level. Refer to Waveguide and Coax Connector Assembly on page 5-11.

At the equipment end, a flexible jumper (waveguide or coax) is normally used to connect the radio to the waveguide in the overhead cable tray. It is at this jumper/

waveguide junction that the dehydrator connection is made for pressurization of the waveguide. Refer to Pressurization Equipment and Installation on page 5-21 for details.

Table 5-1 provides guidelines for waveguide hoisting, running, and fastening.

Table 5-1.Waveguide Hoisting, Running, and Fastening Guidelines

Task Guidelines

Planning the route • Use existing cable support runs and trays, where possible.

• Run adjacent to other waveguide or coaxial cables, except where their routing is poor.

• Do not run the waveguide adjacent to the tower ground wires or electrical services cables.

• Select a route that is unlikely to be damaged by riggers, or that restricts their movement on the tower.

• Do not run the waveguide along the topside of cross-members (to avoid it being stepped on).

• Do not run the waveguide along the tower legs (these are the primary attachment points for pipe mounts).

• Ensure there is adequate physical protection for the waveguide at locations where ice fall from towers may occur.

Hoisting and Running • Mount the waveguide drum on jacks and place at the base of the structure so that the waveguide is paid off from the bottom of the drum.

• For long lengths of waveguide, fix a pulley block to the structure above antenna level, and thread a rope for hoisting.

• Attach the rope to the waveguide using a hoisting grip, or with a secure series of half hitches, and carefully hoist the waveguide into position, while guiding it along the waveguide run.

Position sufficient personnel on the tower and at the drum to ensure the waveguide is fed carefully around possible obstructions and bends.

• Carefully bend and twist the waveguide so that the connector can be offered up to the antenna flange without residual stress on the flanges. Fit the pressurizing seals (without using silicone grease) and bolt the two flanges together using the fixing kit provided.

• The flexibility of elliptical waveguide allows it to be formed, with due care, around tower members and obstacles. Minimum bending radius for the E and H planes, and maximum twist figures (degrees per m/ft) will be specified in the datasheet for each waveguide type/size and must not be exceeded. E and H plane bending tool kits should be available from the waveguide

manufacturer for each waveguide size, and their use is recommended.

• For difficult sections, E or H plane bends or twists, or flexible waveguide may need to be used. These should only be installed as a last resort bearing in mind their cost and extra installation effort.

Figure 5-1.Typical waveguide components: flexible waveguides, E & H bends, twists and a Type N transition

Task Guidelines

Fixing • Holes must not be drilled in any mast or tower steelworks unless authorized by the tower owner in writing.

• The waveguide must be supported by hangers sized to the waveguide and with an adaptor (clamp) suited to the structure. Typical hangers and adaptors are shown in Figure 5-2. Other fastening systems are available and include quick-fit (snap-in) types and stackable arrangements.

• Check the waveguide datasheet for maximum hanger spacing.

Recommended spacings depend on waveguide size, maximum wind speeds and whether or not radial ice loading is experienced at the site. For example, an elliptical waveguide sized for 7.5 GHz operation may have a maximum spacing of 1.5m (5 ft) where wind peaks are lower than 135 km/h (85 mph) and no ice, down to 0.6m (2 ft) spacing for wind peaks of 240 km/h (150 mph) and 25mm (1”) radial ice.

• Ensure the waveguide cannot flex in the wind. Where necessary use rod supports. This may be especially applicable to the traverse between the tower and antenna.

• For waveguide and pressurizable air-dielectric feeders the connector should be fastened to the antenna flange/connector but not weatherproofed until after the feeder is purged, which will be performed on termination of the feeder at the building end and installation of the pressurization system. The reason for this is that the air plug at the antenna-end connector must be removed in the purging process. Refer to Dehydrator Installation on page 5-25.

• Use an appropriate wall feed-through where the waveguide enters the equipment building. The gland around the cable should provide a water, dust and vermin proof seal. Single and multiple waveguide/cable types are available.

• If there is potential for water to enter a building on the waveguide where it passes through a wall feed-through assembly, provide a slight drip loop (sag) in the waveguide prior to entry, or run the waveguide at a slight uphill angle to the building.

Task Guidelines

Figure 5-2.Typical hanger and adaptor items

Hanger

45^o adaptor

Hardware kit

Threaded rod support kit

Hanger bolted to tower Hanger with threaded rod support kit, 45^o angle adaptor and tower

standoff kit

Hanger with threaded rod support kit Hanger with angle adaptor Hanger / round member

adaptor (hanger with circlip)

Tower stand-off kit Angle adaptor

Hanger / round member adaptor (hanger with circlip)

Figure 5-3.Typical wall feed-through accessories