Transmitter Grounding

Most of your preparation and plan should go into having a proper ground system.

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Your coverage depends on your soil conditions and the time you take to do the grounds properly. Recently we completed a single transmitter in Minneapolis with a poor soil condition - because we went overkill on the grounds - the results were better than expected and better than average. Use this page to rank your area. The higher the number, the better results but again that still lays on your ability to get solid grounds in the soil!! Use this link to the FCC Soil maps.

The transmitter needs to be properly grounded (safety ground). See this paper. Use size #10 solid copper wire and connect one end to the binding post on the RANGEMASTER unit. The largest gauge binding post on current transmitters will accept is a #10 wire.
If you use a larger wire as I do, you will need to install a splice a few feet down the line from the binding post to larger wire.
Run the ground wire down to the ground with as direct a path as possible to a ground rod in the ground or other suitable grounding solution.  A ground rod next to the foundation of the house or building should be considered as more of a anchor point.

Sometimes you can get away with using the electrical ground of a building for ground, often it will not work at ALL!  If there is concern about the intentional frequency radiating into an electrical ground a choke could be used, see below. Generally building wiring seems to be poor/negligible radiator. See this link also. The transmitter needs a reasonably direct path to dirt ground with good penetration into ground. Some electrical grounds will not do this. If you find that you are not getting a sharp peak in voltage when you tune the "cap tune" then you probably are using an unacceptable ground (see troubleshooting document). This ground could also prove to be a bad lightning ground also. See the hints page elsewhere for an example how to run a good ground wire. The path should be as straight as possible to dirt ground.

On a large flat rooftop, one instance we grounded to the building steel ladder then continued the line through a vent to the TELCO Board ground with excellent results. You can also check continuity with earth ground with roof sheet metal and roof air conditioner systems (housings). Be careful but explore all possibilities. One customer had fair results with the A/C's Electrical Ground but that in not always the case.
A few commercial office buildings have a ground ring around a parapet wall. The best commercial sites are ones with cell antennas already there as there will be a earth ground point.

Avoid Placing your ground rod to close to your house or building. The ground rod needs to be in good dirt away from the sand/gravel foundation fill of the structure. You can place the ground rod 10-20 feet away from the building and bury the wire (preferably un insulated) a few inches below the ground. What works well is to use a flat blade shovel to create a "trench" the the wire can be laid into. Just insert the shovel into the dirt a few inches and rock it back and forth creating a trench. This way the wire can be installed without digging.

Two ground rods, a 4 foot right at the building for anchor and lightning protection drain with another 8 foot rod 10-20 feet away into the yard for performance can be quite a good system. The rod that is in the yard can be totally buried so it doesn't interfere with traffic, lawn mowing, etc. Later one could add more grounds in various fashions but mainly to surround the site.

If you use multiple rods be sure you don't drive the main junction one in the ground all the way until you are sure you have clamped on all your lines.
Good grounding really pays off and makes for an impressive system.

Remember, all connections must be soldered (clean first), or bright and shiny and the tightly clamped. What you are doing is making an electrical connection with the earth, the more copper / dirt contact the better. All solder and clamped connections need to be weatherproofed. I use this AMSOIL MP Heavy Duty Metal Protector Spray which coats the metal with a wax and guards from all oxidation.
The wire coming from the transmitter needs to be locked down (mounted) so that it doesn't move. The most common range problem is with the ground, either a bad connection, or the ground isn't good. If the ground rod has been put into sand or gravel that will result in bad performance. You want the ground rod into good loamy soil, real dirt, the moister the better. You will notice as time goes by and you keep the ground area watered, the signal will improve.

I also encourage you to read the numerous articles and writings by searching on the web "part 15 ground".

 

 

The below photo shows an excellent ground system which is near Minneapolis which has BAD soil conditions for vertical ground plane systems but because care was taken to do this layout and the grounds were soldered with quality Silver/Rosen core soldier the coverage worked beyond expectations. 2.3 miles radius SOLID signal! We are adding a 2nd transmitter and more grounds so stay tuned to the results!! This system works.

The red T represents the transmitter. The yellow dots are 8' ground rods and the brown lines are the ground radials. The dotted is a future one not yet connected. I will make a 2nd diagram with a step up in performance from this. It just takes a little effort to do this and pays off BIG TIME!

 

Thanks to all the snow I cannot show you the layouts we have done here locally but it's really simple. This photo shows one quality copper clad 5/8th" X 8' pole driven near the foundation for anchoring. The black insulated line leads up to a coupling near the transmitter and is neatly kept away from metal surfaces on the way down. The bare #8 or #6 solid copper will be buried when the soil thaws. The second ground is 20 feet out and ran under and along the overhead power lines which induces the signal that way too. The upper smaller gauge wire was added to settle a floating ground problem which connects the electrical ground to earth. There was an additional ground inside the house to the cold water system from the electrical box which this system reinforces. KEEP THE GROUND SYSTEM MOIST! Although some may not approve, salt water added in the start will quickly result in conductivity with the soil and minerals. This summer on a similar install I am running grounds 360 degrees around the transmitter location then re-tune for maximum efficiency.Be sure to work with a local electrical contractor to get the copper wire at a reasonable cost as that product IS NOT CHEAP retail!! I have another plan this spring where the 3rd ground crosses a garden (excellent soil) then terminates in a creek area which will propagate 5 miles or more. I have it reaching about 3 now thanks to the proximity to that creek.
The adjacent photo was on a roof of a brick building. All concrete surrounding so the ground is attached to the air conditioner electrical ground. I can make other recommendations depending what the property owner will allow. Spend time looking around for safe and efficient ground situations. A current project on a major shopping center allowed me to go through a vent to the main TELCO ground 200 feet away.	Clamp for railings or to ground to the frames of steel buildings, trusses and towers.
	Avoid this! Weatherproof after completing the electrical connection with soldier. Then keep the ground system damp through summer.

This is a good ground as long as they're soldered to the mast. This would be the ideal condition as the mast becomes a ground and of course it's easier to design a 360* ground plane. At the top one could simply ground safely an inch away from the transmitter.

 

Severe "hum" or noise was trapped into the audio path because the electrical grounds created ground loops. We spent some time to eliminate floating grounds. One symptom was a strange static sound when the water was running. That was because of poor grounds through out the cold water pipe systems which were rectified. You can see here that the conductivity was broken with a water softener and this dissimilar metal. Cleaning and re clamping solved the problem.

 

Older homes and structures usually will give you audio hum problems as it's easy to have floating grounds. One example would be a computer or DSL modem which gets power form one power source and the audio equipment is connected to another. The problem is that the outlets are not sharing the same ground system. You can sometimes alleviate the problem with a ground loop isolator which can be found from dozens of electronic stores, etc. These work best after the final stage of the unbalanced audio path.

Short Install Tip

 

 

	The photo to the left's radio is grounded underneath as seen here and on a roof-top air conditioner chassis we verified was also a sound ground.

 

 

 

You may be asking why would the guy mount the AM transmitter so low? Wouldn't the tower ground out or directionalize the signal? - No - in many cases the antenna could be parasitically feeding RF into the tower which matches the frequency more closely ending up in a larger footprint. FCC Rules have no comment on this type of set-up.

Here you see a ground mounted transmitter which works well with a good ground system too but look closely in the air - Because the transmitter is below those high voltage lines, a driver along the road will have good signal up to 5 miles away in this particular case. I'm not prepared to explain why but it works none the less.