Technical Topics > Equipment

Electric charges on receiving antennas

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Ray Lalleu:
EDIT :  this was in a topic about Continental Radio 6270 AM 1816 UTC 01 Jul 2022


--- Quote from: kris on July 01, 2022, 1901 UTC ---- There's a storm around me, I touched the bare leg of the QRM Eliminator case and it pinches me!
I have to turn off the apparatus for safety! :o

--- End quote ---
Electric charges on your antennas. Usually that comes from charged rain drops. You can discharge them to an earth connection, but it's better to use a 1 megohm resistor or back to head diodes in parallel to the earth.
Of course, if the storm is very close, unplug !

kris:
   This situation surprises me! I took a risk and, after disconnecting the antennas, I touched my leg with the antenna cable (screen and middle vein) - nothing pinches! And that's OK because the antenna ballon is symmetrical with a grounded center and through the cable shield it has a good connection to the "ground field" in the garden. The voltage I sense, approx. 35V, is introduced by the laptop's power supply.
I stated this before, but I thought that grounding the antenna set would remove this potential, but I did not check it. I have to work on it because the power supply of the laptop brings the noise level up to about 2S. Thanks for the advice Ray! Once, in a winter, during a snowstorm, Windom kicked me hard - static electricity!
  - delete it after some time, unless, as a warning, move it to the technical thread!

BoomboxDX:
I knew about back-to-back diodes, but the 1 megaohm resistor is also a good idea to remember. I hope to re-erect a 100 ft. wire this Fall, I'll have to keep the resistor in mind.

Pigmeat:

--- Quote from: Ray Lalleu on July 01, 2022, 1906 UTC ---EDIT :  this was in a topic about Continental Radio 6270 AM 1816 UTC 01 Jul 2022


--- Quote from: kris on July 01, 2022, 1901 UTC ---- There's a storm around me, I touched the bare leg of the QRM Eliminator case and it pinches me!
I have to turn off the apparatus for safety! :o

--- End quote ---
Electric charges on your antennas. Usually that comes from charged rain drops. You can discharge them to an earth connection, but it's better to use a 1 megohm resistor or back to head diodes in parallel to the earth.
Of course, if the storm is very close, unplug !

--- End quote ---

You can get bit by a barbed wire fence if conditions are right, which is why most farmers wear gloves when fooling with them.

Most antenna books instruct you to use the 1 megaohm resistor along with the ground rod when it comes to long wires and Beverages.

Wind is the big culprit on bare wire, using insulated wire cuts down on the risk of getting bit. Of course, in a thunderstorm that all goes out the window, as should the wire.

Josh:
Use the highest wattage resistor you can as nearby lightning has popped many a resistor used for such porpoises.

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