GROUNDING AND LIGHTNING PROTECTION for Amateur Packet Radio stations and Telecommunications.

Noise is the enemy of Packet, Data, and Digital Communications. In addition to providing Equipment and Personnel Protection from lightning, a good ground system will reduce noise in your Packet Station, or your mountain-top communications site.
G. E. "Buck" Rogers Sr.

If you follow these Lightning Protection & Grounding procedures
YOU'RE GROUNDED!

ANTENNAS AND SUPPORTING STRUCTURES

Metal antenna structures that are anchored into the ground are inherently self-protected. Some radio systems antennas and beams may be unlikely to be damaged by direct lightning strokes, but they should be bonded to metal supporting structures to eliminate arcing. If the ability of an antenna to withstand direct lightning strokes is doubtful, Lightning rods atop the tower or supporting structure, to intercept strokes should be provided where the transmission pattern permits.

Lightning rods may be attached directly to a metallic supporting structure and should protrude sufficiently above vulnerable elements to provide an adequate "cone of protection". Top lighting fixtures may also be subject to damage if they are not properly shielded. Metallic antenna towers, either guyed or self-supporting, provide an excellent conducting path for stroke currents but the footings, base, and guy anchors of such structures must be properly connected to suitable grounding electrodes.

When wood poles are used to support antennas a lightning rod should be provided at the top of the pole to intercept strokes. This lightning rod should have a large size ground wire cadwelded to it and routed to a good ground system. This will give protection against pole splitting and possible antenna damage. In a common arrangement, a ground rod is attached to the pole with one end protruding sufficiently above the top of the pole to provide a suitable cone of protection. A #6 AWG (or larger), solid, bare copper, down conductor is connected to the rod and stapled directly to the pole on the side opposite the coax or transmission line to the antenna. All pole-top hardware, the antenna, and any supporting guys should be bonded to this grounding conductor.

At the base of the pole the shields of lines, equipment cabinets, and any other conducting objects should be bonded to the down lead which then must be connected to the common area ground system similar to that shown below.

An overview of how a communications site is grounded.
Your site should not contain an independent ground(s). ALL grounds should be connected together as shown in the illustration above. A single point (common) ground is noted by the Master Ground Bar or MGB, as shown. XIT ground rods are chemical rod systems that are used in areas where grounds are hard to achieve. EMAIL Lyncole

The drawing above is a "cut-away" that illustrates how the "XIT" "L" ground is installed. "XIT" chemical ground rods are also available in straight or "vertical" shaft design.

For those who want top level lightning protection, here are a few of the current generation in lightning protection devices.

A ''GAS DISCHARGE TUBE'' Lightning arrestor.

A ''GAS DISCHARGE TUBE'' Lightning arrestor.

Countless hams have watched their precious radio equipment destroyed by lightning induced surges traveling on their coax feedlines. A good Gas Discharge Tube (GDT) type lightning arrestor can help prevent your equipment from being the next victim.

The MFJ270 is an ultra-fast gas discharge tube that safely shunts up to 5000 amps of peak impulse current harmlessly to an independent ground connection.

The MFJ-270 presents a constant 50 Ohm impedance to your transmission line. It has an SWR less than 1.1:1 and an insertion loss of less than 0.1 dB. It can be used up to 1000 MHz. Handles up to 400 Watts PEP. The MFJ270 is supplied with SO-239 connectors and works with most all types of coax fed antennas.

The MFJ270 is trademarked as the Guardian Angel™ is made of heavy duty steel with quality connectors and components. Gas discharge ''button'' tube is replaceable.

Covered by MFJ's famous No Matter What™ one year limited warranty. That means MFJ will repair or replace your MFJ-270 for one complete year.

FYI... No inline device will protect against a powerful, direct lightning hit.

A gas discharge tube 'GDT' is an intergral part of this MFJ 4 port coaxial switch. The "GDT" can be replaced if it is damaged by a lightning strike. Replacement GDT's are available from MFJ ENTERPRISES INC.

An in-line "gas discharge tube" is employed in this Andrew coax cable protection device. The Andrew GDT offers broadband performance from 0 to 2500 MHz. The Andrew Arrestor Plus allows for replacement of the GDT button without having to remove the arrestor from the line. The Andrew Gas Tube Surge lightning arrestor also allows DC to pass when feeding phantom voltage to tower-top amplifiers. Not the cap screw that allows easy maintenance and replacement of the Gas Discharge Tube (GDT) button. NOTE: The ANDREW GDT shown above are available with either Type "N" or the new "DIN" connectors.

The Andrew quarterwave shorted stub lightning protector has been designed to provide the best available protection against lightning. Its unique quarter wave stub system provides a direct DC ground to the coaxial line center conductor while passing signals in a specified band of the 824-2500 MHz range with minimal disturbance. Models are available for a wide range of standard frequency coverages for public service, cellular, and PCS frequencies. Quarterwave shorted stub type lightning arrestors must be ordered for a specific operating band of frequencies (Contact ANDREW at; 1.800.255.1479 or 708.873.2819). CLICK HERE to visit the ANDREW website.
To download the PCS & Cellular System Planner/Design software, CLICK on the Andrew LOGO.

Connectors and mounting surfaces are 100% silver plated to ensure very low intermodulation potential. Mounting may be directly through an ANDREW coaxial copper entrance ppanel, or in-line. Because of quarter wave construction, the Quarter Wave shorted stub type protectors also reject out-of-band signals, actually reducing intermod and desense problems at crowded transmitter sites The "SHORTED STUB" is one of the most effective protectors made, however, they are frequency sensitive devices and must be ordered for a specific band..

The industry "work-horse" is the AEMC 3710 (and 3730) Ground Tester. I consider my AEMC model 3730 to be one of the most "user friendly" devices that I have ever used to test an existing ground system at communications sites.
For more information, Telephone: AEMC (508) 698-2115, (800) 343-1391, or Fax: (508) 698-2118

Digital Ground Resistance Tester Model 4610
(When it comes to making ground measurements and soil resistance tests, this "magic box" is my first choice!)

Measures from 0 to 1999 ohm
Direct reading bridge
Fall-of-potential method
Autoranging
Measures Ground Resistance (3-point) and soil resistivity (4-point)
Step voltage tests
Touch potential measurements
Continuity tests on bonding

The AEMC Digital Ground Tester Model 4610 performs accurate ground resistance measurements (3-point) on single rods or computer grids, and soil resistivity measurements (4-point). It may also be used for step voltage tests and touch potential measurements. The AEMC Model 4610 is autoranging: It will automatically seek out the optimum measurement range. To use the tester, simply connect the leads, press to measure, and read. This rugged, easy-to-use tester is ideal for maintenance crews performing multiple and repetative tests.

For more information, Telephone: (508) 698-2115 (800) 343-1391 or Fax: (508) 698-2118 or CLICK HERE to visit the AEMC web pages..

To order or request additional information about AEMC and other ground test instruments [email protected]
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Here are some rules of safety that could help save your life if lightning threatens.

Stay indoors, and don't venture outside, unless absolutely necessary.
Stay away from open doors and windows, fireplaces, radiators, stoves, metal pipes, sinks, and plug-in electrical appliances.
Don't use plug-in electrical equipment like hair dryers, electric tooth brushes, or electric razors during the storm.
Don't use the telephone during the storm; lightning may strike telephone lines outside.
Don't take laundry off the clothesline.
Don't work on fences, telephone or power lines, pipelines, or structural steel fabrication.
Don't use metal objects like fishing rods and golf clubs. Golfers wearing cleated shoes are particularly good light ning rods.
Don't handle flammable materials in open containers.
Stop yard work, especially when the mower or tractor is pulling metal equipment, and dismount. Tractors and other implements in metallic contact with the ground are often struck by lightning.
Get out of the water and off small boats.
Stay in your automobile if you are traveling. Automobiles offer excellent lightning protection.
Seek shelter in buildings. If no buildings are available, your best protection is a cave, ditch, canyon, or under head-high clumps of trees in open forest glades.
When there is no shelter, avoid the highest object in the area. If only isolated trees are nearby, your best protection is to crouch in the open, keeping twice as far away from isolated trees as the trees are high.
Avoid hill tops, open spaces, wire fences, metal clothes lines, exposed sheds, and any electrically conductive elevated objects.
When you feel an electrical charge; if your hair stands on end or your skin tingles; lightning may be about to strike you. Drop to a prone position immediately!