Because the N3RR station is designed to be a top-ten, single-op assisted station and also be a PacketCluster node serving southern Montgomery County, MD and northern Fairfax County, VA, the design of the station must include provisions to keep the station on the air, even during lightning storms. So, I undertook to design the station so that all equipment inside the shack is always hooked-up to its AC power and its antenna(s). I have never suffered from a lightning hit with this design.
I did suffer a hit to the Ring Rotor control boxes during the time I was re-configuring them and failed to ground them properly. As a result of leaving them unattached to my single-point-ground (SPG), I needed to replace a Zener diode in three of the units. (More on how to ground these units later.)
So, my requirement was to achieve operational capability of my station, 24 x 7 x 365, even in the face of lightning.
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There are several individual items of an amateur radio station that must be considered when designing a lightning protection system:
Each of these items was considered essential to the overall operation of the N3RR station and, therefore, the final lightning protection design included protection for all of them.
Lightning Protection Design Overview
I utilized several resources in determining what system of grounding to include in my ligntning protection system. First and formost, I abided by all of the specifications in
ANSI/TIA/EIA-222-E in effect at the time I implemented my system, 1994. (The current specification is "-F-1996")
Nearly all of the lightning protection design I used was derived from Polyphaser Corporation. There is a tutorial provided by Polyphaser that is very informative. Since Polyphaser provides so much
reference material, I will not go into the theory of operation of my ligntning protection design, but rather, this Webpage will present the design I implemented.
The Ground Grid
Central to any lightning protection system is the grounding system, or ground grid, to which is attached the lightning protection elements and to which all ground busses/wires are attached.
Pictorially, here is the ground grid system I implemented at the N3RR QTH.
The distance from the 52 ft tower to the house is approximately 60 feet.
I used a combination of CadWelding, Andrew Corporation components, and
Polyphaser 1.5 inch copper strap with
SS-30 anti-seize compound from Jet Lube to affect the ground connections.
Also, I used 8 foot copper-clad ground rods with 16 foot spacing between them.
I used Andrew Angle Adaptor Kit Type 31768A (Andrew Catalog 38, Page 600) to attach the ground wire to each
tower leg and each guy anchor.
Both of my towers have angle legs, not tubular. Polyphaser has interface products that will allow the attachment of copper straps/wire to galvanized steel tubular tower legs.
Coax Cable Lightning Protection
Pictorially, here is the ground system with hyper links showing the junction boxes at each tower and the Single Point Ground (SPG) at the house. Click on each hyperlink to view each of the junction boxes.
Whole-House Lightning Protection
Joslyn Model 1265-85 whole-house lightning protection device at the power panel (Shown during construction). With this whole-house lightning protection device, I am much more comfortable that high voltage AC and lightning will not destroy/harm sensitive electronics equipment at the N3RR QTH (Ham and non-Ham equipment).