12

One way to tell is by its effects. Do you hear a garbled version of yourself in nearby speakers when you transmit SSB? Do GFCI outlets pop even though no one is being electrocuted? Does handling the transmission line give you RF burns when transmitting, or change what you hear when receiving? If you had these problems and now you don't, you must have been ...


10

Some older GFCI circuits were known to be susceptible to stray RF. The ARRL recommends replacing these older breakers with new ones that they have listed at the link I provided.


8

A dipole is twice as long as the equivalent monopole. However if the size of a dipole isn't a problem, then certainly it's possible to use one. As Michael Kjörling mentions, you want (by convention) a vertically polarized antenna on VHF, not horizontal as the "T" you have drawn would be. But that's no problem -- we can make a vertical dipole also. The ...


8

Should I drive ground rods into the ground for antenna/RF grounding? Probably not. What you are likely to accomplish is this: (diagram from W8JI) If the lightning hits the antenna, have the same problem in the other direction. The important thing to realize is that the current from a lightning strike is so huge that it will go through all the grounds, and ...


7

Your solution to "RF in the shack" should be proper antenna design first, and grounding second. See Using a balun with a resonant dipole (or any other antenna, really). If you take care to address common-mode currents, you won't need a ground. Regarding lightning protection, you might just forget about it. If lightning has struck your indoor antenna, it's ...


7

"Ground" is not the same thing as "Earth". It may be confusing because the surface of the Earth is sometimes called "the ground", but still this is an entirely different thing than electrical "ground". It is often convenient to define ground to be Earth, but that's no requirement. In a battery powered system far away from Earth, "ground" is likely the ...


7

To add to what Dan is saying, for (horizontal) dipole antennas, ground height is important because although a dipole doesn't require ground to work, ground is still a (lossy) conductive plane, and you still get an image. That is, it appears that there's another dipole, fed in anti-phase, underground. Even if nothing in your transmitter or antenna is ...


7

While ground effects are common concerns in almost every antenna and radio system, they are particularly important in the case of a monopole antenna. Monopole antennas, including quarter wave verticals along with many other electrically short verticals, are different from dipoles because the currents going into the elements do not balance. While a dipole has ...


7

It's true, some GFCIs are just abnormally fussy, and you can attenuate RF on a conductor with ferrites. However, a lot of amateur setups have improperly designed or installed antennas. Common-mode RF currents in the antenna feed system will travel right down the feedline, to your transmitter, down its power cord, and into every other device in your house ...


7

How do I ground this system? Don't. You can't, anyway. Whatever connection you make will be long enough that it will be more of an antenna than a ground. But don't worry, you don't really need a ground anyway. Why would you need a ground? One reason is lightning protection, but that's probably not what you hand in mind, and it's more complicated than ...


7

There are two reasons for the advice to run direct to the battery: Minimize the area enclosed by the power connections. This reduces both interference picked up by the wiring, and inductance (which is undesirable in power supply connections). Minimize resistance. A radio can be a fairly heavy load as car accessories go, so you want to avoid any voltage drop ...


7

With the canal 60 feet away it's not of much help. The objective with a monopole antenna is not just to have any ground connection, but to have a low-loss ground plane under the base of the antenna. The ground plane provides the return current and creates an image antenna. The return current density is highest where it converges at the base of the antenna. ...


6

grounding an antenna mast/tower (outside, lightning prevention) A tower or mast must be grounded to "earth", usually through an 8' conductive (copper) rod driven into the ground as close to the antenna setup as humanly possible. Should the worst happen and lightning strike on or about the mast/tower, you offer the electricity a shorter path to "earth" and ...


6

That statement is wrong on several levels. The antenna is DC grounded so no lighting arrestor is needed. A lightning arrester is needed, even if the antenna is DC ground. The arrester's job is to limit the center conductor's voltage to be not very different from the shield. That the antenna is "DC grounded" isn't worth much. Lightning is not DC. In fact,...


6

what would be the theoretical disadvantages of such a disconnect system? Firstly, keep in mind that antennas don't cause lightning damage: grounds do. It's not clear from your description if your patch panel is grounded at the same point as your electrical service or not. If it's not, you have two separate grounds. This doesn't comply with the NEC, and it ...


6

It's all of the above: an RF ground a 12 V power ground a lightning ground, for what it's worth a chassis ground to prevent "buzz" on the chassis if your shack 0V is not earthed The manual says to connect it to a ground rod, to prevent TVI, BCI. If you used an end-fed antenna without a ground or counterpoise, the mains wiring (through your power supply) ...


6

The picture you have drawn suggests a lightning suppressor installed in this way will do little to nothing to protect your station. The suppressor does only one thing: it limits the maximum voltage between the center conductor and the shield. It doesn't do anything to limit strike current on the shield, which is where most of the energy is anyhow. The ...


5

To answer your first question, yes, it will affect the signal, but it's a good thing. What you do to (RF) ground your antenna(s) depends on what type of antenna you are using. For instance, dipoles do not require a ground. Typical vertical antennas do require a graound though some types such as the GAP Challenger use 3 wires insulated from ground (in this ...


5

What size wire is recommended to bond the antenna ground to the electric service ground? I'd recommend (and electrical code may require) 6 AWG solid wire, both for electrical and mechanical reasons. If the cost is acceptable, flat copper strap is even better since it has lower inductance. Make the connections with brazing or welding if possible. Every ...


5

This design of a crystal radio relies on the capacitance of the antenna and the inter-winding capacitance of the inductor as well as the inductance of the inductor to form the tuned circuit. The length of the antenna can therefore play a role in the ability to tune in AM stations. I agree with Mike regarding the soldered connections. Go through them all ...


5

Congratulations on getting permission to install an antenna. There are many hams that rent that would love to be in your position. As Phil correctly asks, why do you need an earth connection? Here are some possible reasons to be thinking about earthing in your situation. Common Mode Current An OCF antenna is an inherently imbalanced antenna. Such an ...


5

If you are in a jurisdiction that requires compliance with the US NEC (National Electric Code), you will probably find that there is no requirement for grounding the cable or having a lightning arrestor on the cable. This is because the NEC grounding requirement (article 810) starts with the presence of a mast mounted or tower mounted antenna or associated ...


5

If the container is small relative to wavelength, then it won't have much effect at all. If it's very large (say, infinite) then it will reduce ground losses by providing a more conductive ground plane. It doesn't matter if it's actually connected to the soil or not. This is a good thing. The container will be closer to the antenna, which will change the ...


5

The purpose of the ground radials isn’t to ground the counterpoise. The purpose of a dense field of radials is to emulate as much as possible a perfect mirror surface, so that, to the far field, the vertical monopole seems to have a mirror image half that makes the monopole seem more like a full size vertical dipole, with a pattern maxima orthogonal to the ...


5

There are some suitable connections in the reusable Cadweld product line: But you're right, there don't appear to be any similar connections in the One Shot line. An alternative is brazing. An alloy like Harris Stay-Silv 15 works well. I've managed to make acceptable connections (barely) with a good MAP plumbing torch to ground rods that are not buried yet ...


4

Isn't one building a vertical dipole when they make a 'tiger tail' for their HT? For an example and plans see this: http://www.hamuniverse.com/htantennamod.html


4

Another way to detect current on the outside of coax is to run your hand up and down the coax wile an analyzer is connected , if you see a fluctuation on the meter then current is following on the outside. On vhf I built sleeve chokes to remove it with great results. KC5ULU


4

Two drawbacks to ignoring your grounding: You will have a poor(er) signal. You could become the ground and experience an RF burn first-hand. That said, VHF antennas are often not grounded - handhelds and VHF radios in cars, for example.


4

The misconception about grounding is widespread. In the real world outside of hobbies, grounding is an art depending on each situation and location. I have no grounds running down my 3rd floor condo, but I do have solid point-to-point grounding systems for two consoles of radio and computer gear. Do not depend on your house power wiring grounding pin/...


4

Bond it all together. At both ends, if you can. Effective lighting protection isn't really just about providing a path to ground, though that's part of it. More importantly, lightning protection is about having "ground" at just one point so "ground over here" can't be 200V different from "ground over there". This is what you get, for example, when your radio ...


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