- Mobile antenna grounding
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- How to Ground an Antenna: aerial earthing
- Mobile antenna grounding
- grounding a mobile radio
Mobile antenna groundingBeep beep! Going mobile. Installing a ham radio mobile station in an automobile is often the next step for many hams following the establishment of a home station or perhaps as the upgrade from an HT. A ham radio mobile installation greatly expands the utility of amateur radio and increases the opportunity of time to get on the air. Just consider it yet another opportunity to learn and to expand your growing ham knowledge! Let me state from the git-go that there are probably a million feasible different ham radio mobile equipment combinations, installation methods, and techniques for achieving a well performing mobile station in your vehicle. But no matter your individual selection of transceivers, antennas, mounting methods, coaxial cable routing, operating bands, and other factors, some common tenets of mobile installations apply and help to avoid or reduce problems that are inherent in the mobile environment. Much like antennas, every ham radio mobile station is a compromise, but I came close enough to achieving the goals above to be happy. The transceiver s and related components such as an antenna tuner usually reside within the passenger cabin. A ham radio mobile transceiver may be a single contiguous unit or it may have a detachable control head, allowing the bulk of the radio chassis to reside out of sight, perhaps under a seat or in a stowage compartment. The power leads will be routed into the engine compartment to the car battery, while coaxial cable will be routed out to the antenna attachment locations on the exterior of the vehicle. A mobile station installation will require careful planning and component selection to ensure a well-integrated system that suits your needs and meets your mobile operating goals. The Transceiver: Besides your budget, your selection of a transceiver will be driven in large part by the bands on which you wish to operate. While variations exist, mobile transceivers tend to follow one of three primary styles:. With that assumption, the decision then turns to whether or not you want to have HF mobile, too. If you do want to reach out to greater distances with single sideband using the ionospheric skip provided by HF, the decision tree then branches to one of these two common transceiver arrangements:. My choice was a compact all band, all mode transceiver from Yaesu, the FTD. It supported several of my mobile station goals nicely:. Alt link. I clamped mine onto the left side of a console tray in the cabin, arcing the ball joint arm up and to the right so that the control head resides above the center of the console just in front of my gear shift handle and below the environmental controls of the dash board. I tightly zip tied the microphone clip that came with the FTD onto the ball joint and it holds fast just above and right of my knee while driving. The microphone is out of the way but within easy reach without even a glance, right next to my knee. Low clutter and a clean profile! Because the FTD integrated speaker resides in the chassis stowed under the seat, I included an external speaker that rests nicely in one of the forward console compartment bays. I used an MFJ Clear Tone speaker for its compact size and low price, and it sits nicely in the compartment facing the cabin to provide clear, loud audio.
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There is a serious flaw with the suggestion mobile radios be wired across battery terminals. The negative radio lead should actually not have a fuse, and not be wired to the battery post. Early vehicles had both positive and negative grounds. USA passenger vehicles evolved, standardizing on "12 volt" negative ground systems. The resting voltage was around Many large commercial vehicles, however, retained positive grounds. Non-standardization of systems meant two-way radios and other add on equipment was generally designed to operate with either negative or positive grounds. This was accomplished by floating the internal negative supply buss, while grounding all normally accessible external user ports to the case or cabinet. These early systems started the trend of negative fuses, with both power leads directly attached to the battery. This was not harmful, because the equipment had a completely isolated internal "ground " that was electrically isolated from all other leads leaving the device. Once any other lead common with the negative bus leaves the case, it is no longer safe to conned the negative to the battery post. It is also not safe to fuse the negative lead. In most early CB and commercial two-way radios, the negative buss inside the unit fully floated from the cabinet and any external ports. This included commercial two-way radios like the Motorola Motrac, Micor, and other expensive, high-quality, radios. The floating negative was universal across brands including, but not limited to, GE and RCA land mobile equipment. The floating negative allowed use of radios in either negative or positive ground vehicles. It also solved ground loop issues, allowing direct connection to battery posts without fire or equipment damage hazards. Equipment manufacturers had no way of knowing if the final installation would be in a negative ground vehicle or a positive ground vehicle. As a result, systems with a floating negative buss were shipped with both negative and positive power line fuses. The floating negative buss system inside the radio allowed safe direct connection to the battery posts, and safe shutdown if either the positive or negative fuse opened. The floating negative power buss made it impossible for starter or charging currents to flow through antenna cables, microphone, or speaker leads. All exiting connections, as well as the case, were electrically isolated from the negative lead.
How to Ground an Antenna: aerial earthing
Forgot Password? After antennas, station grounding is probably the most discussed subject in amateur radio and it is also the one replete with the most misconceptions. The first thing to know is that there are three functions served by grounding in ham shacks: 1. Electrical Safety 2. Lightning Protection. Each has it's own set of requirements, but not all station setups need every kind of ground. In fact, some setups don't use a ground at all! The articles on this page will help clear up some of the myths and mystery surrounding this popular topic. How important is a ground? Most people say that grounding is all- important, but I have had a few people tell me that grounds aren't necessary. Grounds fulfill three distinct functions. The best ground for one function isn't necessarily the best for another. The three are:. Safety ground. This protects you from a shock hazard if one of the mains or high voltage power supply wires contacts the chassis due to some kind of fault. The requirements for this ground are spelled out in your state's electrical code. The safety ground conductor in your wall sockets should be connected to ground according to this code, and your rig's chassis should be connected to the safety ground. Lightning ground. The requirements for a ground for lightning protection are much more stringent than for a safety ground. The topic has been discussed in this group many times, and there are numerous resources available for learning how to make a ground system for lightning protection. RF ground. This is required only for certain types of antennas-- ones which require current flow to ground to complete the antenna circuit. An example is a quarter-wave vertical. One wire of the feedline connects to the base of the antenna, and the other connects to ground. The connection to ground has to have a low RF resistance, or you'll expend too much of your power heating the ground. A few radial wires will provide a moderately low loss connection. A ground rod will help a little, but the RF resistance will be high, resulting in quite a bit of loss. If it's longer, you can get by with fewer. The requirements for various other end-fed antennas depend on their length. If you use a "complete" antenna like a dipole or a ground plane that is, one that doesn't require your feedline to connect to groundyou don't need a RF ground, as long as you keep common-mode currents off your feedline. A "current" or "choke" balun is most commonly used for this. I live in an apartment, and I highly doubt I can do this. Shallow-buried radial wires are the best. Connection to other conductors just under the surface, like a metal water pipe, is next.
Mobile antenna grounding