[RFI] grounding ... [was DigiKeyer II] (Dale)

EDWARDS, EDDIE J eedwards at oppd.com
Mon Dec 23 11:25:56 EST 2013

Excellent point Mark!  And thanks to Dale for answering all those questions this weekend.

In R56 you are bound to find info that is close enough to what you need to do at you home ham shack.  Also, for ham shack specific concepts read the three part lightning article from QST in 2002 by Ron Block (relation to Roger Block from Polyphasor who wrote the now out-of-print book "Grounds For Lightning And EMP Protection"--some of the diagrams are in the QST article).  Search ARRL.org site for QST articles: http://www.arrl.org/arrl-periodicals-archive-search key word "Lightning".

Main things for hams to focus on for lightning protection: 
(1) ground all cable shields to grounded tower legs every 150 ft or at the top & bottom and/or entry into house; 
(2) solid-tinned, buried, outside-perimeter ground buss w/rods every 16 feet (doesn't need to surround entire house, but must be long enough wire  to connect all cables & utilities grounds; 
(3) surge protectors (Polyphasor or equiv.) on each RF cable entering home and AC surge protection for everything inside; and 
(4) internal radio equipment secondary ground buss tied back to single point master ground buss at cable entry point.

If you do these four things as close as possible to following R-56 specs, you could probably operate your station throughout a thunderstorm; however, since equipment damage risks/costs will come out of your own pocket, you may still want to disconnect and ground all your valuable stuff anyway unless money is not an issue for you.  I disconnect & ground via antenna switches at home, but at work it has to operate 24/7 so we always have some tolerable risk to our 30 radio sites.  Been almost 20 years since we upgraded to R-56 and only lightning failures happen when a tech forgets to ground a new cable somewhere.

Oh, and special rules: 
(1) Never use braided ground cables outdoors or in damp environments (or at all if possible).  Tinned copper or flat straps only if possible.
(2) Avoid copper to steel connections especially grounded steel anchors to avoid galvanic corrosion problems.  Use brass in between.

And for you guys who just cannot get enough from R56, google search for Army Tech Manual TM 5-690 or IEEE Standard 1100.    Happy Holidays and Merry Christmas to all!

73, de ed K0iL

-----Original Message-----
From: RFI [mailto:rfi-bounces at contesting.com] On Behalf Of Mark Hawley

Although this Motorola document is written for commercial installations, the
information is straight-forward enough to apply to more modest amateur
installations and may be of some help. It covers many grounding
configurations and has lots of diagrams.



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