I am looking to optimize my Rangemaster setup. I would like your thoughts on the most effective configuration for my situation.
I am looking to optimize my Rangemaster setup. I would like your thoughts on the most effective configuration for my situation.
Option 1, and the current configuration, has the Rangemaster mounted on a 5′ TV mast that is supported by an eave mount on the far end of the garage. The unit is about 12′ above ground level. An appropriate length of #8 jacketed stranded copper wire connects the bottom of the TV mast to a single 6′ ground rod. I plan to add at least two more ground rods if I can find a source of 6-footers locally. I have discovered, to my dismay, that nobody but nobody sells ground rods any more! Home Depot sometimes has the 8 footers, which I don’t want to use because they are very difficult to put in and impossible to remove later on (should you change your mind).
If I keep this configuration, does anyone have an opinion on how far apart to space the ground rods? The wires interconnecting them will be run on the ground, not from the garage roof. Also, does anyone know who sells ground rods?
Option 2 would be ground mounting in the back yard. Unfortunately, in this case it would only be possible to space the unit about 10′ away from the back of my home. In addition, there are many trees and bushes to contend with, as well as an old galvanized wire fence along the back of my property. Beyond the fence is a river, which is normally meek and mild, but which becomes rambunctious when it floods. I can run radial wires down the bank to the river, but anything I put down there will be swept away in the next flood. I could deploy at least three ground rods and probably some radials (e.g. 16 radials 10′ long, on the ground) in that location.
Option 3 would be to mount the transmitter in the back yard on a short pole, say for example 6 feet, set into the ground. As in option 2, radials could be installed, but I would probably not want to elevate them, so they would be on the ground. The only advantage to this option over Option 2 is that it gets the transmitter a little ways off the ground. But not high enough to clear the house.
Let’s hear your thoughts on these three options. Which would you choose? Or do you have another recommendation? My home is a ranch house with an attached 2-car garage.
That river is tempting…
I’ve wondered about mounting over a body of water.
When I was in Vancouver WA there was a “mit-pond” directly behind my apartment. Mitigation ponds are required in many Washington state communities when the amount of watershed displaced by a large development could create a flood hazard – you might have heard that we get a bit of rain here 🙂 All of the run-off from the roofs, sidewalks and parking lots drains into the mit-pond first, settles there and is slowly trickled into the storm water system.
I was thinking of a nice short copper pipe pounded into the pond botom with the XMTR and ANT mounted there, fed power and content via a weather proof cable.
Especially tempting with the certiified and self-tuning Talking House, because a shorter vertical could be used to offset the ground pipe to absolutely adhere to the 3 meter rule, and with the self tuning I wouldn’t have to stand in the pond and tune the XMTR, or retune it if the water level changed significantly enough to throw the ANT out of whack 🙂 .
I never did that because there were many children at the complex and you just can’t have stuff like that in a common area, even if it’s in the middle of a 100′ x 100′ pond 🙂
I would try to do something close to that nearby body of water.
Experimental broadcasting for a better tomorrow!
Grounding
Hi,
I am going to post here something I recently wrote on grounding. Check back to the RM website later for an updated version, I’m not quite done with it yet. Also the diagrams did not come out here.
Grounding an AM radio system
The AM ground in an AM system is critical, not only for system performance, but also often for lightning protection. The goal is to provide a low resistance connection to the local Earth, less then 25 ohms if possible, less then 5 ohms is ideal. The ground resistance in an area will be determined by your ground system and:
• Moisture content of soil
• Mineral content of soil
• Soil type
• Soil contaminants
In general the higher the moisture content, the lower the resistivity will be.
What you are trying to do is make an electrical connection to the earth over a broad area. What that means is if you have multiple rods keep them at least 6 feet apart, don’t concentrate on just a small area of dirt. For example don’t place 10 rods in a 2 foot circle. The more yard area you can cover with your system the better. A 20 foot diameter circle would keep the rods about 6 feet apart. Keeping the system spread out allows the currents to flow more efficiently.
Working with different installation sites you have to be creative in making a good ground. You may find existing structures and/or items that can help you connect to the Earth. A buried tank, deep well casing, metal fence, Metal tube lawn sprinkler system, all can be useful.
• Sand and gravel, even when wet can make a poor ground.
• Use corrosion resistant connectors when possible
• Solder (electrical type solder) all connections or be sure all connections are bright and shiny & then tightly clamped.
• You can use an Earth resistance meter to check the resistivity value of your system. Also see the troubleshooting page of the transmitter manual.
• If you are connecting to a utility water pipe, connect to it within 5 feet of where it comes in from the dirt. This keeps someone else from coming in later and putting in non-conductive pipe, making your ground useless.
• Sodium bentonite can be used to enhance a ground.
• If you are using ground radials, they should be as long as your antenna is high to be effective.
• Try to use the moistest dirt possible. For example if there is an air conditioning system, install a rod where the condensate drips. Look to see where the rain comes off the roof to find moist areas. Look for any creeks or ponds.
• Generally the deeper your rod, the lower the resistivity will be.
Bury any horizontal wires, the more ground/dirt contact the better. Just an inch or two below the surface will do. You can use a flat blade shovel to create a “trench” that the wire can be laid into. This works well with lawns. It is best to bury your rods entirely if possible to avoid anyone tripping over them, the lawn mower hitting them, ect.
The type of trench ground system above can work well with sandy soil. (diagram missing)
R-F Grounds
Even a ground system of one or more ground rods having ZERO ohms of resistance to earth potential around them will not provide a zero ohm connection to the r-f currents that the ground system needs to collect and return to the antenna/tx system.
For minimum loss those r-f currents must be gathered where they first enter the earth, after radiation by the antenna. If they have to travel through more than a few inches of lossy earth to reach the perfect ground of the above paragraph, then much of that current will be absorbed by the earth, and converted to heat. For that reason a radial system and/or ground rods in a creek bed some distance from the antenna itself would not be a very good choice.
It is essential that the r-f ground system collect and return those r-f currents, because their sum is the amount that will flow into the 3-m radiator at the output of the transmitter — therefore are directly responsible for the amount of available power that will be radiated. This performance is best supplied by a system of radials extending in all directions outward from the base of whatever is supporting the tx+whip.
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