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Warren and all
For a single service 1/4 wave system that may be true,
my point is that there is a VERY REAL RISK of injury from these systems
especially in the UK
Many of the MF broadcast systems here have
multi-coupled transmitters, and the mast is not a 1/4 wave at all these
frequencies. The medium wave band spans about an octave. On smaller systems the
antenna is electrically quite short compared to 1/4 wave.
The DPI is frequency dependant but can
be quite high (at least in the reactive part) leading to very high voltages at
the base.. Multiplied by 4 or more transmitters each running 50
to 200kW of AM
Mast base insulators that i am familiar
with are typically rated at 120kV and there are some systems
where the peak voltage here is the limiting factor for the numbers of services
we can actually run into the antenna at once.
I have seen small mammals and birds bridge the
spark gaps.. there is not much left after.
if an arc is generated, it ionises the air along
the path, and this forms quite a good conductor to the nearest earth.
If the nearest earth is you...
Arcs are also capable of being sustained for quite
a while.. they do not necessarily cause the transmitters to trip.
A brief note about the effects of MF RF
currents
The current will actually flow mostly over / through the
upper layers of your skin, you will not be electrocuted. That would be a
kindness
You will however be subjected to extreme temperatures
associated with the plasma of the arc. These will be worst at entry and exit
points for the RF current flow.
The guy holding the plants in the video almost certainly
had small burns under his gloves, as an arc would form there too.
That's why he was felt pain without there being any obvious cause (from the
video)
The effect would be like touching an arc welder.. there
is probably not enough voltage to do any harm, but would you put you finger
where the arc was struck?
RF burns wont necessarily kill you but lying helpless
and undiscovered because you have severe burns etc. and can't walk,
could.
I am merely pointing out that what the guys in the
Ukraine did was incredibly foolish, but they got lucky.
If someone were to try the same trick on the wrong site
they may not be able to post their exploits on Youtube
Sent: Sunday, December 23, 2012 4:58 PM
Subject: Re: LF: Unusual radio mast video Ukraine
??
Mark,
I don't know what the power of the system is but
I suspect that since at the base of 1/4 wave antenna the voltage is lowest this
might be running substantial power. Also note that they are drawing arcs with
grass, not metal or a graphite pencil. Very likely that they would have been
killed if they had used a metal spike to draw the arc or if they had been
standing on damp ground etc.
73 Warren K2ORS
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