David wrote:
I agree that in the coax side, there is no real 0V because the current has a
standing wave. But the transceiver has a DC power supply (normally 12V) that
is controlled or modulated. One side of the power supply is regarded as 0V
and connected to 0V rail of circuits. The modulated side is the RF live that
is connected to the centre contact of transceiver output connector.

In theory, while transceiver is transmitting, if I touched the outer of the
output connector, I would not expect to get a shock or RF burn. If I touched
the centre contact of output connector, then I would expect to get a shock
or RF burn. Admittedly, I could touch the outer and find that I am close
enough to the centre contact for RF to capacitively couple into me. In real
life, I would never touch the output connector while the rig is
transmitting.

Does RF live and ground not exist on the output connector of the
transceiver?

Begin with a self-contained, battery-powered transmitter. Put a large
metal plate on the ground, stand on the plate, and set the radio on the
plate. Touch the radio. No burn. Touch the center conductor. Burn. Just
like you said.

But now put the radio on top of an insulator, and connect the center
conductor of the antenna connector to the metal plate. Touch the center
conductor. No burn. Touch the radio. Burn. Whoa -- you got burned from
"0V" -- the "cold" side! No fair!

Finally, insulate the radio and disconnect the center conductor from the
plate. Hold on to the radio and touch the center conductor. Burn. Hold
on to a wire going to the center conductor. No burn. Touch the radio
while you're holding the wire. Burn.

You don't prevent a shock by declaring or "regarding" something to be
ground or "0V". You do it by connecting it to the same potential as your
body. And declaring it to be "live" doesn't cause the burn -- what
causes it is that you're touching something that's at a different
potential than your body.

Roy Lewallen, W7EL