If I touch the coil in my tuner while transmitting I get a painful rf burn.
But a bird can perch on my antenna wire while I transmit 100 watts and it
stays there seemingly without a care in the world. How come?

If I touch the coil in my tuner while transmitting I get a painful rf
burn. But a bird can perch on my antenna wire while I transmit 100
watts and it stays there seemingly without a care in the world. How
come?


although an over-simplification, the bird is not touching anything
else, (grounded)... but you are.

even if you aren't touching something you have a much larger surface area to
act as a capacitive path to ground for the rf. the small bird being a long
distance from ground and having a smaller area has much smaller capacitive
currents.

"Ed" wrote in message
. 192.196...

If I touch the coil in my tuner while transmitting I get a painful rf
burn. But a bird can perch on my antenna wire while I transmit 100
watts and it stays there seemingly without a care in the world. How
come?


although an over-simplification, the bird is not touching anything
else, (grounded)... but you are.

"Dave" wrote in message
. ..
even if you aren't touching something you have a much larger surface area
to
act as a capacitive path to ground for the rf.

snip

Yes. One of the standard tools used during RADHAZ inspectiions at RF
transmitters sites is an RF Burn Gun. (It's shaped like a gun for
convenience of holding and use.) It measures the RF potential on metallic
structures near a transmit antenna and the tech is part of the circuit,
coupling to ground. Current limiting in the RF Burn Gun keeps the tech from
harm while he reads the potential off a meter in the "gun."

It strikes me that the measurement accuracy varies with operating frequency
and size of the tech (via collective X-sub-C). With my big butt and short
legs, I might offer more coupling to ground than you scrawny people.

There's a great difference between working on antenna conductors and
60 Hz power lines.

Body capacitance is all-important at HF. At 60 Hz it is the
conduction path which matters. Workmen can be enclosed in Faraday
screens.

Frank Alforo wrote:
If I touch the coil in my tuner while transmitting I get a painful rf burn.
But a bird can perch on my antenna wire while I transmit 100 watts and it
stays there seemingly without a care in the world. How come?

You could probably hang by one hand from a 20 kV power
line and be OK as long as you didn't complete a current
path to another wire or ground.
--
73, Cecil http://www.qsl.net/w5dxp

"Cecil Moore" wrote in message
.com...
Frank Alforo wrote:
If I touch the coil in my tuner while transmitting I get a painful rf
burn.
But a bird can perch on my antenna wire while I transmit 100 watts and it
stays there seemingly without a care in the world. How come?

You could probably hang by one hand from a 20 kV power
line and be OK as long as you didn't complete a current
path to another wire or ground.
--
73, Cecil http://www.qsl.net/w5dxp

Beware of the gradient!

"Cecil Moore" wrote in message
.com...
Frank Alforo wrote:
If I touch the coil in my tuner while transmitting I get a painful rf
burn.
But a bird can perch on my antenna wire while I transmit 100 watts and it
stays there seemingly without a care in the world. How come?

You could probably hang by one hand from a 20 kV power
line and be OK as long as you didn't complete a current
path to another wire or ground.
--
73, Cecil http://www.qsl.net/w5dxp

You should have seen the TV educational channel where in some countries they
have a basket type trolley that men are put in and hung by helicopter on the
multi megavolt lines. They do wear some kind of suit that is conductive so
the charge will not affect their body so much.

"Ralph Mowery" wrote in message
. net...
You should have seen the TV educational channel where in some countries
they have a basket type trolley that men are put in and hung by helicopter
on the multi megavolt lines. They do wear some kind of suit that is
conductive so the charge will not affect their body so much.

You mean these guys? http://www.haverfield.com/

--
Gerry

Ralph Mowery wrote:
"Cecil Moore" wrote in message
.com...

Frank Alforo wrote:

If I touch the coil in my tuner while transmitting I get a painful rf
burn.
But a bird can perch on my antenna wire while I transmit 100 watts and it
stays there seemingly without a care in the world. How come?

You could probably hang by one hand from a 20 kV power
line and be OK as long as you didn't complete a current
path to another wire or ground.
--
73, Cecil http://www.qsl.net/w5dxp


You should have seen the TV educational channel where in some countries they
have a basket type trolley that men are put in and hung by helicopter on the
multi megavolt lines. They do wear some kind of suit that is conductive so
the charge will not affect their body so much.


They ;do that in this country. Mesh suit of some metal, can't remember
which metal but not important as long as it's conductive I guess.
Great job I bet, big bucks....