On 8/2/2011 12:24 PM, Sal wrote:
wrote in message ...
On 1 Aug,
This replaces one which failed a couple of years ago constructed with
thin insulated 5A lighting flex not much more than bell wire that had been
up
nearly 30 years.

This got me thinking. (Dangerous, yes, but I occasionally risk it.)

Since a normal dipole has current max near the center, is there more
localized heating (I-squared-R) nearer the feed point? Seems like it ought
to be. Can you overheat a small wire and make it fail there by melting?????

No, I don't want to try it. I'm hoping somebody knows. Exciting story even
better.

"Sal"



Fusing current is remarkably high for small conductors in free air, even
for 100% duty cycle.

AWG30 (0.01" diameter) = about 10 Amps (Preece equation)

Scales as 1.5 power..
so, going to AWG 20 (.0316") - about 50 amps..

Considering an inverted V dipole with feedpoint Z of 50 ohms, at 1kW,
the current is about 5 amps...

So running that legal limit amp with a brick on the key to your AWG30
stealth antenna won't melt it. (it probably will get pretty warm.. and
corona at the ends might be spectacular)