Shortwave Antennas Page 2

Copyright © 1999-2011 by Harold Melton KV5R. All Rights Reserved.

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Safety First!

Power Line Safety

Every year, people are killed because they allow an antenna or support to contact overhead high-voltage power lines. Remember: Never, NEVER run any antenna wire, feedline, support line, or guy wire OVER OR UNDER power lines !!! The antenna, support, or guy can fall into the power line — OR the power line can fall into them. A wet antenna support rope will conduct high-voltage. NEVER assume it is safe to run a rope or string over or under power lines.

NEVER raise a pole, mast, or tower is such a way that it could fall into a power line !!!

Get help. Tie off safety lines (dry nylon rope) perpendicular to and away from power lines. If your mast is 40 feet high, erect it 45 feet or more from power lines. NO EXCEPTIONS!

To reduce power-line induced noise in your shortwave radio, shortwave longwire antennas should be run perpendicular to, and away from, utility power lines.

Lightning Safety

First of all, long antennas do not “attract” lightning. They merely act as long inductors that get a voltage spike from the nearby lightning arc. Nevertheless…

Every year, people are killed because they ignore simple lightning protection measures. The basic lightning arrestor is simply a grounded spark-gap device. You can buy them, or make one from an old spark plug.

All large antennas — even horizontal wires run low to the ground — increase the risk of electrocution and/or property damage from atmospheric lightning. The simple rule is: the longer the wire, the more voltage will be induced upon it by a nearby lightning strike. This voltage will leap off the end of the wire in a fat blue spark, and you will hear it pop. Any time you hear thunder, disconnect the antenna wire from the radio. Put the end in a glass or jar and lay it on the floor near the wall. If you have a radio ground wire, clip the antenna wire to it instead.

You don’t need a direct strike to have lightning damage. Any strike within a mile will produce an electromagnetic pulse that will induce thousands of volts on your antenna wire, probably damaging your radio. If you get a direct hit, it will probably destroy your house, with or without a lightning arrestor.

NOTE: A lightening arrestor only drains away small pulses — it will NOT protect you or your house from a direct strike. ALWAYS disconnect the antenna from the radio when storms are approaching! Do not leave an unattended radio connected to an outdoor antenna. Tell the whole family!

Legaleze

Antenna erection in the vicinity of power lines can be a FATAL activity! Your safety is your responsibility — not mine! THE AUTHOR ASSUMES NO RESPONSIBILITY FOR YOUR USE OR MISUSE OF ANY INFORMATION HEREIN.

The author cannot guarantee nor warranty that the plans and information herein are perfect in every detail, nor that your use of them will satisfy your needs. The outcome is entirely your responsibility. They are intended simply as a guide for you to use in designing and building something to suit your own needs. Every antenna installation is different.

Radio Shack is Registered Trademark of Tandy Corporation. My mention of Radio Shack products in these plans should not be considered an endorsement, just that they are readily available and of reasonable quality. I am under no agreement with Tandy Corporation.

FALLS AND OTHER HOME HAZARDS

Every year people are killed or injured by falling off houses, out of trees, off ladders, etc.

DO NOT climb trees! Shoot a line over with a slingshot or fishing pole. Then, use the fishing line to pull over a stronger line (#18 nylon Mason’s line). Then use that to pull up ¼″ nylon (or better, UV-protected dacron). Then pull up a pulley, with more ¼″ nylon looped through it. You CAN use trees without leaving the ground!

MAKE SURE ladders are strong and stable. Sink the legs of the ladder into the ground before climbing. Have a helper hold the ladder. Read the warning labels. Use common sense.

NOTE: It is not legal (under FCC regulations) to modify antennas on certain products like cordless phones and FRS radios. Check your owner’s manual.

Continued…

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