Shively Labs 6822, Instruction Manual Installation, Operation, & Maintenance, Page: 47 / 78

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Installing the De-icer System (if applicable)
7 Installing the De-icer System (if applicable)
Precautions
WARNING
Don't expose personnel to the medical hazards of intense radio fre-
quency (RF) radiation. Whenever working on the tower in the area of
the antenna, turn off all transmitters and lock them out so that they can-
not be turned on accidentally.
CAUTION
All parts of the de-icer system within approximately 20 feet (6 meters) of
any radiator must be shielded from RF energy, and the entire outdoor
portion of the system must be made waterproof.
CAUTION
An improperly installed de-icer can overheat and damage your antenna.
De-icer system
description
The de-icer system consists of the heating elements in the bays, their branch
cables, a bay junction box for each antenna bay, interbay cables, and a "pig-
tail" of wires about 10 feet (3 meters) long which you will connect to the
tower junction box you are to provide. The following will help in installation:
• System electrical schematic: Figure 34 on page 43.
• Electrical specifications: Table 3 on page 39.
• Thermostat readings: Table 4 on page 44.
Your system may also include specially-ordered items, such as a ground-
mounted main control box, a power cable extending up the tower, or a tower-
mounted dual-setting thermostat.
Dual-setting thermostat
CAUTION
Remember that conditions may be favorable for icing on the tower, even
if they are not on the ground.
Shively Labs deicers are designed to prevent ice from forming on antenna ele-
ments and are not designed to melt ice that has already formed. For this rea-
son, Shively Labs recommends that the system be installed with a tower-
mounted dual-setting thermostat assembly (Shively Labs Model 55522-G502)
and de-icer control box (Shively Labs Model 94068) that ensure the deicers
are operated in the temperature range ice is most likely to form.
Electric power
The de-icer system requires 240 VAC, 50 - 60 Hz., single-phase. Table 3 shows
approximate heater leg resistances and current draw, respectively.
Table 3. De-icer specifications
Heater leg
resistance,

Heater leg (T1 or T2)
current draw, amps
1-Bay 288 0.42
2-Bay 144 0.84
3-Bay 96 1.3
4-Bay 72 1.7
5-Bay 57 2.1
6-Bay 48 2.5
WARNING
Installation should be per-
formed only by personnel
experienced in RF sys-
tems, qualified in electri-
cal work, and familiar
with this equipment.