E.F. Johnson Company 242-20X1-213, Руководство пользователя

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INSTALLATION
2-4
August 2000
Part No. 001-2001-200
The operating temperature range is -30°C to
+60°C (-22°F to +140°F), i.e. the same as the repeater.
The fan is thermostatically controlled by the internal
temperature. When the internal heatsink temperature
r45°C (113°F) the fan turns on. When the
heatsink temperature drops below +35°C (95°F) the
fan turns off. If the internal heatsink temperature
r90°C (+194°F) the power supply turns off
until the heatsink temperature drops below +85°C
(+185°F). The over-temperature shutdown and restart
are automatic.
2.7 GROUNDING
CAUTION
PROPER SITE GROUNDING AND LIGHTNING
PROTECTION ARE VERY IMPORTANT TO PRE-
VENT PERMANENT DAMAGE TO THE REPEATER.
As in any fixed radio installation, measures
should be taken to reduce the possibility of lightning
damage to the Viking VX equipment. Proper ground-
ing eliminates shock hazard, protects against electro-
magnetic interference (EMI) and lightning.
Ground each piece of equipment separately. Do
not ground one piece of equipment by connecting it to
another grounded piece of equipment. A good DC
ground must be found or created at the site. Rooftop
site grounds can be researched through the building
management or architects. Tower site grounds must
be made with grounding rods. The many techniques
for providing adequate grounds for towers and poles
and for installing building ground bus lines are beyond
the scope of this manual. Refer to National Electrical
Code article 250 "Grounding Techniques," article 800
"Communications Systems" and follow local codes.
The ground bus should be routed to the floor area
within 5 feet of the system with a runner of 6 AWG or
larger solid copper wire or 8 AWG stranded copper
wire.
The outer conductor of each transmission line at
the point where it enters the building should be
grounded using 6 AWG or larger solid copper wire or
8 AWG stranded wire.
Secondary protection (other than grounding) pro-
vides the equipment protection against line transients
that result from lightning. There are two types of sec-
ondary protection, RF and Telephone Line. Use the
same wire sizes as specified for coaxial cables for any
ground connections required by the secondary
protectors.
RF
An RF protector keeps any lightning strike to the
antenna feed line or tower from damaging the Repeat-
ers. Install this protection in-line with the combiner
and antenna feed line.
RF protectors are selected by calculating the
maximum instantaneous voltage at the output of the
combiner. Do this by using the following equation.
V
P
= 1.414 (X) (
√
P(50))
where:
V
P
= Voltage at the output of the combiner.
P = repeater output in watts
X= for VSWR=
1.05 1.10 : 1
1.09 1.20 : 1
1.13 1.30 : 1
1.17 1.40 : 1
1.20 1.50 : 1
1.30 1.86 : 1
Example: Repeater power output of 60W with a
VSWR of 1.3 : 1 (for this VSWR, X = 1.13):
V
P
= 1.414 (1.13) (
√
60(50))
V
P
= 1.59782 (
√
60(50))
V
P
= 1.59782 (54.772256)
V
P
= 87.52V
Telephone Line
There are four types of protection suppressors for
telephone lines; Gas Tube, Silicon Avalanche Diode,
Metal Oxide Varistor and Hybrid.
The hybrid protector is ideal for E.F. Johnson
equipment, and is strongly recommended. A hybrid
suppressor combines several forms of protection not
available in just one type of device. For example, a
high-speed diode reacts first, clamping a voltage strike
within 10 ns, a heavy duty heat coil reacts next to
reduce the remainder of the current surge, and a high-
powered three-element gas tube fires, grounding Tip
and Ring.