A Ground Breaking Review on Grounding Your Station?

 

Grounding.

It’s one of those topics that can be as diplomatic and mutually respectful as discourses on political favorites and religion on the HF bands.

There are a lot of facts on the subject as well as a lot of folklore being passed around, and quite a bit of legitimate differing opinions.

Grounding is really two quite separate (hopefully) subjects, although they often get confused with each other. There is the concept of an electrical ground related to your house power and covered by the National Electrical Code (NEC) article #250 (covered very nicely in: fyi.uwex.edu/mrec/files/2011/04/W4.-Biesterveld-NEC-grounding-MREC2010.pdf , and www.mikeholt.com/instructor2/img/product/pdf/1292448885sample.pdf (you really don’t want to read the NEC’s actual article – it can be rather “dry”). RF grounding is discussed very nicely by Polyphaser, a company that manufactures a lot of equipment to perform this very feat, at: www.radio2way.net/Polyphaser%20Guide.pdf . I would urge anyone particularly interested in these subjects to read these references.

First, let’s put electrical grounding to rest. In the bad old days not only were electrical devices not required to be grounded, but there weren’t even polarized plugs to make sure that the ‘hot’ and ‘neutral’ lines weren’t accidentally swapped. Those people old enough to remember the old 5 vacuum tube “All American Five Radio”, will no doubt have had the experience of being electrocuted by holding onto the back of the chassis in one hand and any local ground in the other (it happened to me, and might be the explanation for a few things that happened to me later on). Suffice to say, electrical codes have, thankfully, changed, and this and such dangers should be a thing of the past. Your electrician and your local electrical utility should make very sure that you have a ground wire fully bonded with the Earth ground when it enters your home and stays very close to Earth ground. There are times when equipment is interconnected in such a way that “ground loops” occur with their resultant 60 cycle hum that we all know and loathe. The quick and dirty way to deal with them is to “float their ground”, or isolate the ground plug away from the AC receptacle, usually using a two to three wire power adapter:

This is the ‘quick and dirty’ solution, and like most ‘quick and dirty’ solutions, it will work in the short run, but increase your risk of getting bit on the arse at some later time if/when you develop a short to hot on your chassis and fail to notice it until you are semiconscious from a sudden bout of electrocution. Hamius Emptor! “Let the Ham beware” if you choose to “float” your electrical ground.

Electrical grounds should be addressed by a licensed Electrician and your utility company. What we will address for the remainder of this article are RF grounds, chassis grounds and lightning dissipation grounds (since they all inevitably get dealt with at the same time by the cautious Ham)!

Although it might seem advantageous to deal with both kinds of grounds simultaneously, by using your outlet’s electrical ground for your station’s RF ground, I would strongly advise you against such folly as the possible problems outweigh any possible benefit. Both types of grounds can be bonded together, often with an additional RF choke, but this should not be done at the level of your Radio Shack itself, but at the entry of your electrical utilities.

Let me start off by advising people that some Hams “float” their RF grounds entirely. If they are fortunate not to have too much stray electrical currents in their shack and wise when lightning storms approach this can be a viable option.

Proper RF grounds can improve isolation from local currents by giving them an opportunity to be bled to an Earth ground, diminishing background noise, which is always desirable. Excessive lengths of a conductor to ground in the HF/VHF or UHF range can possess significant inductive impedance that would impede the dampening of the local currents. This is why a relatively short length of flat, highly conductive copper strapping arranged in a “starfish” configuration with individual short lengths connected to a copper busbar, which is then connected directly to an earth ground, rather than a daisy chain type of configuration where the wire lengths end up being much longer, is the rule here.

                             

Keep it as short, and keep it as straight as you can.

If you need your ground strapping to be very flexible, like at the hinge of a car’s hood for bonding different metallic parts into a single ground, then braided strapping is an acceptable compromise. If you are building a stable stationary ground system, then solid copper strapping is the preferred way to go.

Another aspect of an RF ground is in dealing with unbalanced antennas, that are not truly a complete RF radiator, but rely on some additional element to serve to “balance” it to a degree and provide something similar to an antenna’s counterpoise, ground plane, or its radials. This can be an aspect of the ground connector on your transmitter, linear amplifier, and or antenna tuner. It is for this aspect that “artificial grounds” offered by such manufacturers as MFJ can be useful. They amount to a mechanically shortened counterpoise, electronically lengthened by a variable tuned circuit. They might offer some improvement in your poorly implemented antenna and provide some noise abatement, but they are band aids on a festering sore – an indication that your antenna system could use some improvement and they offer no help in the third and final aspect of an RF ground:

Lightning protection.

Depending on your location, altitude and surroundings you may require serious lightning protection. It is here where Polyphaser’s document would be very useful. Whether a single well placed grounding bar will suffice or a series of ground bars bonded together depends upon your particular situation – they each have their own individual benefits and problems. The one thing that I must universally urge my fellow Hams NOT to consider is lightning protection systems that offer your local lightning an escape to a ground potential inside your house. All lightning protection should be set up with a ground potential outside and away from your home. Letting it “inside” will be worse than inviting local robbers inside your house!

Outside grounds are primarily 8-foot copper clad steel rods hammered into your ground, either singly or as a group that is well bonded together. A poorer second choice would be cold water pipes used to water your lawn, fire escapes and perhaps your metal fence. Large blocks of metal which are not physically grounded to Earth ground may help in the first two aspects of RF grounding, but they will not be terribly effective in lightning protection.

What can you do as far as inside your home or apartment?

Well, your final option is your plumbing. In the good olde days plumbing was all metal-to-metal and often soldered together, but now we live in an age of Teflon “plumber’s Tape” and entire lengths of nonconductive plastic pipes, so check your plumbing before you use your bathroom’s cold water pipe or even worse, your radiator’s hot water pipe, but if that’s all the Universe has given you, lotsa luck!

Stay safe!

…and have fun!

 

73,

Roy AC2GS