Please, take attention that a
50- Ohm dummy load is switched there. Why? The switch has position
when the antenna is grounded. It is very useful at lighting time
or time when static could copy on to antenna wires. It is time
of strong winds, snowfall or before lighting period. When antenna
is grounded the static goes to the ground and could be not damaged
devices that are switched to the Coaxial Switch. However it is
worked well when antenna does not contains a ferrite transformer
(s) in the design. If antenna had ferrite transformer in the design
and the antenna is grounded to the natural ground, antenna current
caused by static or lighting discharge may be strong enough to
destroy the ferrite transformer.
I use to the switch with Beverage
Antenna that is described at that issue (Antentop
01- 2015, pp.: 35- 41). My Beverage Antenna has ferrite matching
transformer at the end. So theoretically the transformer may be
damaged when switch grounded the antenna directly to the ground.
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At professional radio communication
an antenna that has ferrite parts in the design newer being directly
grounded to the natural ground. Such antenna is grounded through
a low ohm resistor that as usual has nominal equal to surge impedance
of the transmission line. In this case the current going through
the antenna ferrite parts would be limited by the resistor and
the ferrite parts would not be destroyed by the lighting and static
electricity. I use 50- Ohm coaxial cable so I turn on my antenna
to a Dummy Load 50- Ohm when the antenna is not in use.
The main lack of the Coaxial Antenna
Switch Protax CSR- 5G is that one position
rotary switch is used at the device. So grounds of all devices
connected together at the switch. It may be caused that interferences
catching by one device may penetrate to another one having common
ground. Professional Antenna Commutator as usual has 2 position
rotary switch that commutate simultaneously
input and ground of antenna or used device.
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