Is there any danger that the ends of my verticals radials could set the leaves
in the woods afire? There's high voltage there at the ends, right?

Rick K2XT

Rick wrote:

Is there any danger that the ends of my verticals radials could set the
leaves
in the woods afire? There's high voltage there at the ends, right?

Rick K2XT

right!

On 27 feb, 02:18, (Rick) wrote:
Is there any danger that the ends of my verticals radials could set the leaves
in the woods afire? There's high voltage there at the ends, right?

Rick K2XT

Hello Rick,

It will depends on the power, when it is up to several hundreds watts,
I think it is not likely.

Probably you will use about 3 or more radials, so the current and
hence the voltage at the end will not be as high as in the vertical
radiator. The strong E-field very close to the ends will generate
heat in fresh wood/leaves. However before the material will become
flammable, the water has to evaporate. When the water contents
decreases, the loss factor will decrease also. Because of this, the
heat generation per volume will decrease also.

Other issue is corona breakdown directly to foliage. Highest voltage
at the ends will be in case of quarter wave and 5/8 antenna. A Halve
wave will induce significant lower current into the radial system (and
hence lower voltage at the ends).

You might do an experiment and point the material in question towards
the end of the radials (parallel with the E-field lines and grounded).
Take some distance, turn on maximum power and afterwards (power of)
check for temperature rise. This may also show possible effects of
corona breakdown from the radial wire(s) to the material under test.

Best Regards.

Wim
PA3DJS.

I can't really answer the question, but in 49 years of hamming
I've never heard of radial ends setting anything on fire. I'm
interested in seeing more replies to your question.

Irv VE6BP

Rick wrote:

Is there any danger that the ends of my verticals radials could set the leaves
in the woods afire? There's high voltage there at the ends, right?

Rick K2XT

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Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada

I've never heard of radial ends setting anything on fire. I'm
interested in seeing more replies to your question.

Well, let's think of it this way. You sure wouldn't grab hold of the end of a
quarter wave vertical with a kilowatt of power applied to it. Same for the
end of a single raised radial because it would have similar high voltage on
it, would it not? We would put a big old insulator on it to support it if
this was our antenna configuration, right?
Ok, say we laid the one radial made of insulated wire on the ground. Now the
earth would detune it ???????? Would it still have extremely high voltage at
the end? And if so, could it arc to earth? That was my question. I really
dont have 1 radial at the present time, I have 20 so the current divides 1:20
and the resultant voltage at the end of each radial may be nothing to be
concerned about. I don't know, that why I asked on this cold winter night.

Rick K2XT

I agree with your theory. I once had a vertical with one horizontal radial which
was about two feet off the ground. It was fed with open wire line.
The design came from the ARRL handbook. To me it would
be similar to an inverted Vee set in an odd position, and the HV should be
present at the end of the radial however I never really did anything to
check it out with respect to HV at the end -- maybe just as well!

Irv

Rick wrote:

I've never heard of radial ends setting anything on fire. I'm
interested in seeing more replies to your question.

Well, let's think of it this way. You sure wouldn't grab hold of the end of a
quarter wave vertical with a kilowatt of power applied to it. Same for the
end of a single raised radial because it would have similar high voltage on
it, would it not? We would put a big old insulator on it to support it if
this was our antenna configuration, right?
Ok, say we laid the one radial made of insulated wire on the ground. Now the
earth would detune it ???????? Would it still have extremely high voltage at
the end? And if so, could it arc to earth? That was my question. I really
dont have 1 radial at the present time, I have 20 so the current divides 1:20
and the resultant voltage at the end of each radial may be nothing to be
concerned about. I don't know, that why I asked on this cold winter night.

Rick K2XT

--
--------------------------------------
Visit my HomePage at http://members.shaw.ca/finkirv/index.html
Visit my Baby Sofia website at http://members.shaw.ca/finkirv4/index.htm
Visit my OLDTIMERS website at http://members.shaw.ca/finkirv5/index.htm
--------------------
Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada