Well... the corona itself won't damage the receiver. but... the center
conductor of the coax connected to the antenna at the top of the tower will be
at the same voltage as the antenna relative to the ground at the base of the
tower or at the shack. Important note, measuring a voltage always requires 2
points, a reference and a measurement point, in many cases the reference is
implied, with lightning or other ground related measurements you must specify
the reference point or the value is meaningless. That said, since the voltage
from the shack to the top of the tower can be very high, if there is nothing to
equalize the center conductor and shield/ground voltage (assuming of course
that the shield is connected to the radio chassis which is also connected
somehow to ground), yes you could damage a receiver. However, most kinds of
filters, lightning arresters, static bleed resistor or coil, tuner, or anything
else that has a path to ground at the shack end 'should' equali
ze this and help protect the receiver.
An antenna may provide more points for streamers to be initiated to complete
the path to the downward leader, though if the leader coming down from the
cloud is that close its probably going to hit the tower one way or another.
with the antenna at the top of the tower it is more likely the antenna will be
hit than stuff below it on the tower... but it is possible to hit the side of a
tower or building.
Also an aside about 'past performance not being an indicator of future
performance'.... analyzing lightning strokes if full of all sorts of
statistics, I do that as part of my job. not getting struck for years, or
getting struck and not getting damage, is no indication that you are safe over
any future period. Lightning stroke density and current is extremely variable,
so much so that we recommend using at least 10 years worth of averaged data for
making any type of predictions... and determining the probability of hitting
any particular wire on a power line is still a subject of much debate.
Apr 22, 2015 09:17:55 AM, rstealey@hotmail.com wrote:
Good explanation to add to what Tom wrote. Thanks.
The question still remains, however, Can this corona popping damage the
receiver?
And you provoke and even more serious question now, Is the tower/antenna more
likely to be hit by lightning because of the aluminum yagi with the corona.
As an aside, there is a wouff hong perched on the tip of the mast, in an
attempt to ward off lightning as well as QRM. It has worked well for 17 years,
at least the lightning part.
(Just kidding)
And I'm sorry, hotmail won't let me delete the attached text.
Rick. K2XT
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