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I have had the opportunity to use several different ground radial configurations with my Rangemaster over the years. In all the installations the transmitter was mounted on a iron pipe at least ten feet in the air. In all cases, the”safety ground” lead (12 gauge insulated) to the 4-8 foot ground rod, was run down the pipe on old television twin-lead style standoffs. The pipe was not connected to the ground terminal on the transmitter. The ground radial system(s) were connected to the bottom of the safety ground lead at the ground rod. The reasoning to the use of ground radials is to provide a low resistance path for an electrical potential to discharge.
The minimum number of ground radials used was 4 and the maximum was 16. The radial conductor length was about 20 feet. Additional length didn’t seem to perceptibly increase “listen-ability”. The transmitter, operating with just a ground rod, consistently could be heard out to about 100 yards without objectionable noise. The more radials, the greater the distance. The radial systems were spaced evenly 360-degrees around the ground rod, laid tight on the ground with metal clips and not buried. 16 radials increased the signal to 3/4 of a mile without objectionable noise. I can image that 32 ground radials would significantly increase the signal in comparison to just four radials. The transmitter required re-tuning after each change in the ground system. More radials did seem to cause the tuning dip to be sharper. Terrain, buildings and obstructions did punch holes in the signal area and shorten range.
It is important to isolate the mount pipe from the transmitter ground to keep it from radiating. The safety ground conductor should be allowed by inspectors just because its good engineering practice. Its in the rules. The safety ground conductor connects directly to the ground terminal on the transmitter. Don’t forget the standoffs. This arrangement will allow you to put a choke and/or ferrite beads (filter) on the conductor if the inspector requires it.
The ground radials can be as small as 20 gauge insulated copper bell wire. The radials carry very little current and a surprisingly high voltage (100-200 volts) because of their high impedance when the system is properly tuned. Results from your own installation may vary from mine.
