Toward a Better Ground Station
My station is located in Kennebunkport, Maine, a small town on the coast about 90 miles northeast of Boston, and it is probably best described as an average ham installation. It consists of several transceivers with no amplifier, a tri-band beam at about fifty feet, a vertical for the five bands 10 thru 20 meters, a 40 meter sloper, a Windom antenna for 40 and 80 meters, and a two meter packet connection. My interests include DXing, contesting, and rag-chewing – particularly on digital modes – and my achievements thus far include working about 260 countries, all states on several modes, and all 3076 US counties.
In the years since installing the tower and beam, and particularly since monitoring the reflector, towertalk@contesting.com, I learned that there were a number of things that I should have done differently. The tower is located in a semi-swampy area behind the house and is well-grounded at the base. The rotor cable and the coax cables for the beam, sloper, and Windom antenna were routed down the tower to a point about eight feet above ground, and from that point overhead to a storage shed and then along the side of the house to the room where the shack is situated. They entered the house in close proximity to the electrical main and telephone line, and went directly to the operating desk on an interior wall. Lightning protection consisted of coax switches with internal gas discharge tubes, but the only ground connection in the shack was to the coaxial shields and the electrical system ground. I would usually disconnect the electrical and antenna cables during electrical storm season – if I remembered. Sporadic bouts of RF feedback and telephone interference were reminders that the ground system was less than ideal.
At some point in the past I had obtained a copy of The “Grounds” for Lightning and EMP Protection published by PolyPhaser Corporation, and I had subscribed for a while to their quarterly newsletter. For those who have not ever seen the manual, it is best described as a reference source for protection against damage by lightning and electro-magnetic pulse. It may be purchased for approximately $23, and excerpts (as well as other data) are available at the web-site, www.polyphaser.com. (Let me point out here that I have no connection or interest in PolyPhaser, other than as one who believes the statements made in their documentation.)
During this past summer I perused the manual and the PolyPhaser product catalog for about the sixth time in as many years, and I realized that there were several things that I could and should do which would improve the station grounding and lightning protection, and the appearance where the cables had been attached along the side of the house. First would be installation of a what PolyPhaser called a ‘single-point ground panel’ near where the coax and rotor cables entered the house. This panel would be connected to a eight foot ground rod driven immediately outside the house and on the panel would be mounted suppressors for the coax, telephone, and rotor cables, as well as the fore-mentioned coax switches. The second step would be the re-routing of coax and rotor cables so that they ran underground within PVC conduit. This would look better, and more important, it would according to PolyPhaser, greatly reduce the likelihood that a lightning strike would follow the cables into the house.
At this point I did make an effort to determine if there were products by another manufacturer that should be considered, but I kept returning to the PolyPhaser products even though they were slightly more expensive. Inquiry revealed that the Ham Radio Outlet did not stock the products, but Amateur Electronic Supply did and they shipped them so that I had them for the weekend. A trip to the local Home Depot resulted in bringing home seventy feet of PVC conduit, fittings and cement, an eight foot ground rod, ground wire, and clamps for less than thirty dollars.
I removed the old coax and rotor cables from the side of the house, and decided to replace the coax but reuse the rotor cable. Five lengths of coax (two are spares) and the rotor cable fit easily inside 1″ diameter PVC, and my xyl and I were able to route the cables and bury the conduit in an afternoon. I did not purchase a PolyPhaser ‘single point ground panel’ because it was smaller than what I needed, but I chose to make my own from an aluminum panel which I fastened to an interior wall and securely clamped to the ground wire which ran from the operating desk past the ground panel through the wall to the ground rod immediately outside. On the panel I mounted coaxial switches and PolyPhaser suppressors for the rotor, telephone, and each coax cable.
I am very satisfied with the result. First and foremost, I have the peace of mind coming from knowing that the job was done in almost complete compliance with PolyPhaser’s recommendations. Secondly, the unsightly wires are gone from the side of the house. Last but not least is the fact that signals definitely seem to be improved with less pickup of man-made noise, and there is no RF feedback or telephone interference. In the event that the station might someday suffer damage from an electrical storm, at least I know that I made some effort to prevent it from happening.
What didn’t I do that PolyPhaser suggests? First, instead of using #4 wire from the single point ground panel to the ground rod, they suggest using 1-1/2″ copper strap because of its lower inductance. Second, they recommend that each coax line be grounded at ground-level where they leave the tower, as further preventative, to keep electrical energy from reaching the house and equipment. (I plan to do this next.) Third, they recommend a series of ground rods at the base of the tower spaced 6 to 10 feet apart and interconnected with copper straps, instead of just one. (Since the tower is in such a wet area I am confident that it is well grounded with only one rod.) Fourth, they suggest installation of a surge protector on the main electrical service. (I will investigate the cost of this step. I did install an uninterruptible power source for the computer this summer, and wish I could afford the luxury of a large unit for the station equipment.)
Originally posted on the AntennaX Online Magazine by Bob Boyd, W1VXV
Last Updated : 3rd May 2024