Grounding the Hamilton Transmitter
Hamilton recommends running a ground wire straight down from the transmitter, attached to an 8' ground rod.
But if put in the middle of a roof, can it be grounded with a series of radials or wire mesh? Or is the ground rod the best?
They also recommend putting it on a 20' mast. Does the groud wire go straight from the transmitter to the groud rod, or does it connect somewhere at the base of the mast as well?
Here's a link on grounding the Rangemaster: http://www.am1000rangemaster.com/hints.pdf
Thanks. I already have a copy of that.
But I'm cofused about a ground rod vs radials, and am wondering if the radials can be on the roof and if that would be as good as the ground rod.
1. Yes, the radial system is as good as the ground rod. The radials act as an "artificial" ground or "counterpoise." The transmitter should be mounted as close to the center of the radial system as possible, and the base of the vertical antenna mounted just above the radial system.
2. If you have a ground connection available on the roof, like water pipes to/from air conditioning, connect the center of the radial system to that.
Thanks Trenonsee.
If using the radials on the roof, do I still want to put the transmitter up 20' on a mast? Then the radials go out from the base of the mast? Do you know about how long the radials should be and how many there should be?
1. If you are using the single-element whip directly attached to the Rangemaster, it would be best to have your radial system center directly below the transmitter, so the radials would be elevated if you mast-mount the transmitter. You can slant the radials down from the center and secure them to the roof near the edge.
2. The radials should be at least 3 meters long, and preferably as long as possible. There is nothing that says that the radials must all be the same length, although if you have a rectangular roof, with the transmitter centered on it and all radials brought out to the roof edge, this might give you a slightly "squished" radiation pattern, with the signal a bit stronger in the directions of the "long" radials.
3. If you look at the radial diagram for the Rangemaster, I think it indicates 64 radials, each of #12 wire, attached to the center ring of #4 wire. If you can't put up 64 radials, put up as many as you can. Generally, the more radials, the better the ground system. There is also nothing that says you have to attach all the radials at once. I would recommend no fewer than eight radials, preferably sixteen, to start with. You can add more later and have your listeners comment on any change in your signal.
Hope this helps.
Elevated ground systems are not uncommon in AM radio. For years, KSPO in Spokane had their antenna on top of a building downtown. Their radials attached to several other buildings. There was a station in Seattle that had a T-type antenna and its ground system was on the roof.