Q Butch, KE5DE, asks, “I have a 10 foot braided and tinned ground wire running to a 6 foot ground rod driven into soil outside my shack. If I ground my rig in this fashion, I get a terrific hum on my transmitted signal. If I disconnect the ground, the hum disappears. This doesn’t seem to make sense. Any ideas?”
A You didn’t say what band(s) cause the problem, but I wouldn’t be surprised if this is limited to one or two bands at most. There are two possible causes. One is that you may have an alternative path to ground that is unknown to you. This could create a ground loop. Another possibility is that the length of braid you are using for your ground rod connection is long enough to pick up a fair amount of RF and conduct it back to the chassis of the radio (this would most likely be true on 10 and possibly 15 meters).
Examine your station with an eye toward “return signal” paths. Make a note of all the possible ways current can flow through ground wires. This includes both the “safety” ground of the ac outlet and the “neutral” return paths for both ac and dc power. Make sure also that your station ground is a single-point type. Run a separate braid to each piece of equipment, then join the individual braids into a single braid that connects to your ground rod.
If all else fails, try changing the length of your ground braid. Make it a bit longer and see if that helps. If the braid is indeed picking up RF, lengthening the braid slightly may prevent it from being resonant on the band in question.
From QST August 1999
