E F Johnson Company 2422001-1 Benutzerhandbuch

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 
reaches +45°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 
reaches +90°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.

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.

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

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.