Antenna and tower work are never far from our minds as hams. Most amateur loads are considered light by professional installers, but they can be heavy enough to cause injuries if mishandled or poorly secured. This article is an overview of ropes, knots, and slings which are used by hams. Since most of us are not professionals, it’s always a good idea to review and brush up our skills before “game day.”
Two complementary resources are sold by DX Engineering: “Up the Tower” by K7LXC and the ARRL’s “Antenna Towers for Radio Amateurs” by K4ZA. The first features a lot of information on rigging, including ropes, slings, and tools. The second discusses how to properly build a tower system. You should review both of these references, which go into far more detail than this article.
OnAllBands also features an excellent five-part series, “Amateur Radio Tower Safety,” featuring W3YQ. Please be safe when climbing and working aloft. Take advantage of the excellent training material that is available to you!
Except for the lightest loads, always use a suitably rated pulley or block when raising and lowering items. Avoid the small hardware store pulleys that are not rated for heavy loads. Light-duty hardware is often stamped or labeled as unsuitable for climbing and lifting—heed that warning!
The snatch block is the most useful since the rope does not have to be threaded through the pulley—one side opens so the pulley can be placed directly on the rope, even when it is tied off at both ends. This is called “snatching the rope.”
The snatch block pulley shown in the photo is rated at a working load of 24 kN (kilo-Newtons), which is about 5,400 lbs. Marine and construction pulleys are also available, although they weigh more. Get pulleys with sheaves that fit your rope so it can’t slip and jam between the sheave and body of the pulley. Watch for sales and have a few pulleys in your tool kit.
For basic tower and antenna work, Dacron and nylon ropes are preferred. A kernmantle rope has a braided sleeve that protects the rope’s core. For tower work, use a 3/8 or 1/2 inch rope because they can handle heavy loads and are easier on your hands than thinner ropes. Inexpensive polypropylene rope is useful for light lifts—such as the tool bucket or a rotator. Wear sturdy gloves when working with a rope under load so that if the load slips, your hands won’t be burned from friction.
Remember that to lift something to a certain height, you’ll need at least twice that length of rope, and another 50% of length is recommended. Try to have at least two load-rated ropes available.
There are two strength ratings for rope: breaking strength and working load limit. The breaking strength is usually three times the working load rating. Try not to use ropes near or at their load limit.
Using ropes as temporary guys should be done with caution and rarely, if ever, as permanent guys. Stretching varieties, such as nylon, should never be used as a guy line. Use a low-stretch rope material, such as Dacron, and be sure it is well within its load limit.
There are many, many types of knots and you should find a how-to book or website that shows how to tie the basic knots. If you’re a beginner, some essential knots are demonstrated on the Columbus McKinnon YouTube channel. This site is about entertainment rigging, which is a lot like basic ham radio rigging! For more advanced knots, resources such as animatedknots.com show you exactly how to tie knots (it also includes a beginner’s section).
The most common types of knots used in antenna and tower work are hitches that pull on or lift tubing and tower sections. The below photo shows two half hitches:
Another common knot is the bowline, which is very useful because it doesn’t slip and can be untied relatively easily, even after being used with a heavy load. I use it for tying ropes to antenna insulators because I can untie a bowline even after the rope has been out in the weather for months.
There are lots and lots of instructions for how to tie a bowline. Many of us of a certain age learned the “make a hole next to the tree, the rabbit comes up through the hole, goes around the tree, and back in the hole” method. This video, however, is probably easier to learn! You might also try to learn the one-handed bowline so you can tie a secure knot with one hand while the other is holding a load—a not unusual situation aloft.
To attach a rope to a structure, a climbing harness, or other rope, carabiners are often used. An assortment is shown in the photo below.
Clockwise from top left are a D shape wire gate, straight gate, oval shape straight gate, auto lock, and twist lock. The straight gate versions are the most common in antenna and tower work.
Note the load ratings in the middle. The highest rating of 24 kN is the breaking load with the gate closed. The working load is one-third of the breaking rating. The smallest value is the maximum load with the gate open. Lightweight clips that look and act like carabiners are often sold as keychains or hangars but should never be used for lifting loads! They are stamped with warnings showing they are not to be used for load lifting.
Rather than tie a rope directly to the workpiece, a synthetic web sling is much more convenient to use. Visit Hoistwire.com for images of various web slings, including common types such as the endless sling and those with eyes at the end. There are also rope, wire rope, and chain slings, but those are not often used for ham radio jobs.
For a complete table of single-ply web sling ratings, see Table 22 “Rated Load for Two-Ply, Class 5 Synthetic Webbing Slings Expressed in Pounds” here: OSHA.gov.
The three most basic uses of slings are straight, choker, and basket as displayed at PracticalMaintenance.net, which shows many ways of using slings and how to determine the load rating of each method.
An assortment of web slings comes in handy for antenna and tower work. Most lifts will use slings from 18 to 36 inches long. One inch wide slings will handle nearly all antennas. A pair of 36 inch slings configured as a bridal hitch make a stable and strong way to lift a Yagi boom. I recommend having at least two slings of several lengths.
If you plan on lifting a tower with a boom truck or crane, use heavier slings that are two inch wide or more. Consult with the crane operator first.
Finally, you really need to take good care of anything you depend on for safely working on antennas and towers! After the job is done, lower your ropes into a plastic milk crate or bucket. The rope won’t tangle and will then pull out easily without kinking or knotting. Larger and longer ropes can be wound on a portable hose reel.
As you store ropes and slings, inspect them carefully for chafing or cutting that may have occurred in use. Look for carabiner gates that are twisted or won’t latch securely. Damage beyond superficial wear is enough to warrant replacement.
If your crew is going to be bringing some of their own gear, label your stuff! A permanent marker will help you keep your gear separate from that of others. Colored tape will also make it easy to tell everyone’s stuff apart.
Ropes and slings need to be kept clean, dry, and away from where rodents and insects can get at them. Avoid kinks and sets by making sure there are no tight knots or bends in storage. Keep them away from oil and grease that might degrade the fibers.
Take care of your gear and it will take care of you!
Editor’s Note: DX Engineering carries a variety of rope in a range of diameters and break strengths, along with rope hardware kits to work with different sizes of Mastrant rope.
The post Ham Radio Tech: Knots & Slings appeared first on OnAllBands.
Going mobile? Installing a ham radio station in your vehicle expands the usefulness of amateur radio, making automobiles ham shacks on wheels. It’s a convenient way to have instant emergency communications onsite without any tedious setup. You can even treat yourself to park and POTA—no picnic table needed.
Those of you who have moved to mobile radio operation probably started with combination VHF/UHF radios. Some go the extra mile and later add HF radio to the mix. Either way, ham radio mobile installations can present some unique challenges for the operator. Anyone who has shopped for a car or truck in the last 20 years has found that Detroit took away a lot of the radio space that we can utilize. Yet, we still adjust and improvise.
There are many different ham radio mobile equipment combinations and installation approaches that can result in an efficient mobile station. Every ham radio mobile station is a compromise, but you can do things to improve both operating flexibility and range, no matter what vehicle you drive.
Few amateurs search for a new vehicle with the idea of creating a mobile station in mind. In most cases, they already own a vehicle and decide to operate mobile. Either scenario presents its own set of issues. Minivans, SUVs, RVs, Jeeps, station wagons, crossovers, and plastic/fiberglass bodies present challenges.
One of the most useful features found in some mobile rigs is the remote head, which allows you to separate the controls from the radio and save space. Choose a mounting location that will put your remote head within easy reach and be easily viewable. The best rule of thumb for every mobile installation is to secure your equipment properly. You don’t want a flying station in the event of a panic stop—or a collision.
One example of a secured solution is the Lido LM-300 Gooseneck Mount that attaches to the seat bolt, allowing the remote head to be easily adjusted. Cup holder mounts like the heavy-duty Lido LM-820 expand to fit by twisting the base, establishing a friction fit. It also has a swivel to adjust arm position.
Sometimes you’ll find that what you need came with your radio. My Yaesu FTM-400 Mobile Transceiver had a mounting bracket for the remote head. Everything fit in a cubby located on the dash side of the console, secured by two small sheet metal screws and industrial strength Velcro. Another good solution I’ve seen recently is a mount that clips into the seams of the dashboard.
Based on personal experience, suction cup mounts aren’t always reliable, especially in the heat. Vent clip mountings vary greatly in quality. Better ones have adjustable tensioning and secure both on the horizontal and vertical planes. Forget the double-sided super-duty tape. Sometimes it holds, sometimes it doesn’t, and it can be difficult to clean after removal.
The radio’s main body should be mounted in a location with proper airflow around the entire unit. Avoid closed areas like tight cubby holes, center consoles, glove boxes, trunks, and storage boxes. Open areas in the rear of SUVs, mini/full-sized vans, and hatchbacks are acceptable as they maintain the same temperature as the rest of the interior. Under passenger seats is a popular mounting location for the radio body—just be sure not to disturb any existing wiring.
Sound Advice
Install an external mobile speaker—it will make the audio much clearer and easier to hear, especially if you have the radio mounted under the seat or back in the cargo area. They don’t have to be high-fidelity, but you want clear audio at voice frequencies.
Speakers like bhi’s DSP NES10-2MK4 and West Mountain Radio’s WMT-58407-948 ClearSpeech DSP Noise Reduction model increase audio levels and noise canceling technology. Remove noise and interference and crank the volume to overcome road noise.
My car has an auxiliary input so I can connect the audio out from my rig to the car stereo. This way, the audio comes out the car speakers and I can use my steering wheel controls to adjust the volume. I can even adjust the tone from the radio controls to make it sound better than the built-in speaker.
Best Antenna Locations
Antenna location makes all the difference. Regardless of where you mount one, it’s the metal mass directly under the antenna that counts, not what’s alongside. Increasing the antenna height may also increase distance, so mount your antenna as high as possible.
The center of a vehicle’s roof is a very good place to mount a VHF/UHF antenna. However, creating an optimal ground in this position involves drilling a hole. If you choose this path, seek professional help from your dealer or a qualified installer. You could use a mag mount instead, but the only ground path is through capacitive coupling, which is lossy in comparison.
Trunk mounting is second best. It’s probably the easiest location to place VHF/UHF antennas, loaded UHF/VHF/HF antennas, and small screwdriver antennas like the Diamond SD330 3.5-30 MHz model. Seam mountings and clip mountings are commonly used here, but it’s important to make sure they are well grounded (bonded) to the frame. If your vehicle doesn’t have a trunk or rear hatch, the front fenders or cowl areas are good alternatives.
Locations like bumpers, trailer hitches, and ball mounts on the rear quarter panels round out the list. They’re the solution for tall antennas like a 102-inch whip, Hustler HF Mobile System, large screwdriver antennas, and hamsticks.
With screwdriver antennas, you’ll want to keep as much of the coil in the air—above the metal— as possible. Putting the coil right up against the body will result in greater losses. If you have a pickup truck, mounting in the middle of the center of the bed with the coil raised has proven to be a good strategy.
One of the most important mobile purchases you’ll ever make is the antenna. Choosing the right antenna can help improve your reception and transmit range.
When you’re shopping for VHF/UHF mobile antennas, don’t take the dB gain figures as fact— think of them more as a guide. Yes, most of those antennas will have some gain to them, but how and where you mount it will affect its performance. You’re better off with an effective mounting location instead of just comparing dBs of gain, so choose the best antenna to fit your needs over its specs.
Longer antennas may perform better. But consider this—a 1/4 wave VHF/UHF has a relatively high angle of radiation, making it easier to reach radio communication sites located in higher places, like repeaters. So they’re more useful in mountainous and metropolitan areas with tall buildings. A 5/8 wave antenna radiates and receives more energy toward the horizon and can have up to a 2-3dB gain over a 1/4 wave. They’re best used in the flatlands and suburban areas.
HF antennas are a different animal. All of them are a compromise to some extent, especially on 80 and 40 meters. All of them will allow you to make contacts—even DX QSOs. But their efficiency, overall length, quality, design, sturdiness, and ease of mounting will vary. The most important thing to look at is overall antenna efficiency, your specific needs, and how the antenna can be mounted on your vehicle.
Many HF mobile antennas require some kind of impedance matching to obtain a reasonable SWR. Overall length is also important in obtaining good efficiency, but there are practical limitations for antenna height and placement on vehicles. Driving around with a 33-foot vertical radiator for 40 meters would be silly—and dangerous.
Probably the most efficient HF mobile antenna is a Texas BugCatcher, followed by the screwdriver (easiest to operate), Outbackers and similar multibanders, single-band Hustler, hamsticks, and base-loaded antennas, in that order.
There will always be some level of common mode current flow in any mobile installation. That’s because there is always ground loss, even at VHF/UHF frequencies. The more ground loss, the higher the level of common mode there will be. Causes include poor antenna mounting techniques, such as using magnet mount antennas or clip mounts on the hood, trunk, or luggage rack. Trailer hitch and bumper mountings can increase common mode significantly.
Proper choking of these currents must be done to help improve your signal to noise ratios (SNR). Using ferrite cores (Mix 31) is essential in minimizing RFI produced by today’s vehicle microcontrollers. Vehicle wiring doesn’t always provide enough slack to install multiple-turn toroid cores. Under these conditions, use multiple snap-on cores if there is enough wire space available.
Don’t forget chokes on power connections to the radio. You’ll also want two chokes on the feedline—one right at the antenna and a second where the feedline enters the vehicle. The one at the antenna is especially important if you’re using a screwdriver antenna.
We’re not referring to 007 here. This kind of bonding involves making low impedance connections among the conductive parts of your vehicle to make a workable ground plane.
To improve RFI noise reduction and antenna efficiency, bond horizontal body surfaces together, such as the hood and trunk to the rest of the vehicle body. This is done by attaching short pieces of tinned copper braid across the hinge connections of the hood and trunk. The braid connection helps to electrically join these surfaces into a single massive ground plane. For pickup trucks you may also improve the ground plane by bonding the bed to the cab, using braid segments underneath the truck and utilizing existing bolts as connection points.
Also consider grounding the exhaust system on cars and trucks, which can act like an antenna. Electrically bond your exhaust pipe to the vehicle frame at three or more points, spread out along its length. Attach the braid to the pipe using clamps and use screws with star or tooth lock washers and soldered ring connectors to ensure a good connection to the car body or frame. Ready-to-install kits specifically for exhaust system grounding are available, or you can homebrew your own.
Remember, the primary goal is to maximize the ground plane under the antenna and to improve the conductivity at RF frequencies. This alone will help control many of the issues with mobile operation.
The post Tweaking Your Mobile Installation for Best Performance appeared first on OnAllBands.
Space, the final frontier for antenna installations. The ham’s ongoing mission: to explore their shrinking lot sizes and seek out smaller antennas that will keep them on the air—ones that boldly perform with the fewest compromises.
There’s nothing that says you can’t bend or wrap antenna elements to make them more compact. Think of open folded dipoles or the end droop on a wire antenna when it’s a few feet too long. Keep in mind that making a dipole smaller by wrapping it back on itself reduces not only the size but affects bandwidth as well. Regardless, this might be a good tradeoff under the right circumstances.
Another advantage is that all the antennas mentioned here resemble an outdoor clothesline to some extent. They look like they belong in the backyard, perhaps making them more acceptable to a ham’s family and the neighbors. Just make sure they don’t hang wet shirts or socks on the wires since it will negatively affect SWR.
A hexbeam, or hexagonal beam, is a type of directional antenna for amateur HF bands. The name comes from the hexagonal outer shape of the antenna—not curses put upon them by HOAs. Its design resembles a modified two-element Yagi-Uda antenna, consisting of a W-shaped dipole and a reflector but no directors. The finished design looks something like an upside-down umbrella.
Hexbeams consist of six arms of non-conductive materials, such as fiberglass or plastic pipes. Insulated wire is used for the elements. In the original design by Mike Traffie, N1HXA, there were two W-shaped elements. Steve Hunt, G3TXQ (SK), later modified the design. Hunt changed the dimensions and shape of the antenna elements, resulting in an antenna which retained the original W-shaped driver, but with a semicircular reflector.
The Hexbeam can be built as a single or multiband antenna to cover different frequency ranges. Popular combinations cover 20m, 15m, and 10m (3-band) and 20m, 17m, 15m, 12m, and 10m (5-band), like DX Engineering’s XB-5 Hexx Beam. There are also eight-band models on the market. The antenna elements for the lowest frequency band are located at the exterior of the antenna, with the higher frequency bands moving inward toward the center.
Driven elements are dipoles for each band. The spacing of each element is critical because the elements of a multiband hexbeam influence each other. If the elements are not parallel, antenna characteristics may change. The spacing between the ends of the driver wires are adjusted for the best compromise between gain performance and SWR. This spacing is maintained using an insulated cord spacer between the tips of the reflector and the driver.
A hexbeam has slightly less forward gain than a two-element Yagi (5 dBi or 3 dBd) depending on the band. It beats the Yagi with front-to-back ratio across the band, reaching peaks over 20 dB. The hexbeam is also broadbanded, with the SWR comfortably under 2:1 at the band edges. For a relatively small antenna, the hexbeam holds up well against the Yagi given its size, and far exceeds the performance of multiband mini beams.
Given all these advantages, there is one minor downside. There’s more work involved assembling all those wires and spreaders than there is working with aluminum tubes. I had some hands-on experience assembling one for a display at Hamvention—and this one was a scaled-down version to fit in the booth area. It just takes some time, patience, and reading the manual prior to assembly. Real hams do read the manual. It’s worth the effort. Editor’s note: The DX Engineering XB-5 Hexx Beam (below) has been designed with fewer parts for faster and easier assembly compared with competing models.
The cobweb was developed by G3TXQ. It was a variation of Steve Webb, G3TPW’s CobWebb antenna, consisting of concentric dipole element sections for each band that are bent into the shape of a square. The outer element is the largest and is tuned for the lowest frequency band. Elements for other bands are nested inside the larger outer loop. The feedpoints of all dipole elements are connected together and driven by a common transmission line.
The cobweb antenna is relatively small yet offers good overall performance. The below MFJ-1836H six-band version (20-6m) is easy to install in limited space, with a compact 9 x 9 footprint. It’s a lightweight structure with a low wind-loading cross-section, making it a robust antenna.
Gain is slightly lower compared to a traditional dipole (1-2 dB less peak gain), which is offset by the nearly omnidirectional pattern of the cobweb. There aren’t the deep pattern nulls off the ends you’ll see with a dipole. The bandwidth (>2:1 SWR) fully covers the 20, 17, and 12m bands but may require a tuner on parts of 10, 15, and 6m for full coverage. I’ve also noticed it has a low noise floor with less static than my other antennas.
Only one coaxial feedline is needed. To match the cobweb’s impedance of 12.5 ohms, it must be fed using a 4:1 matching transformer or balun to match it to a 50-ohm transceiver. A 1:1 balun is also needed to feed this antenna to prevent common mode currents and achieve optimal radiation. If a current balun is used, no additional choking on the coax is needed.
Cobwebs are typically fixed mounted antennas that don’t require an antenna rotator or a tall mast. You can expect reasonable performance at 10 feet, but 20 feet or more is recommended. If you want to include 30 and 40 meters, you’re in luck. The MFJ-1838 8-band version has a 12 x 12 footprint, or you can add a conversion kit to the six-band model.
The halo antenna is commonly used for amateur radio operations. You’re probably familiar with the mobile and VHF/UHF versions. It’s a circular loop of wire that is bent into the shape of a halo or a doughnut—with a bite missing. The halo antenna is known for its omnidirectional radiation pattern, which means that it can transmit or receive signals equally well in all directions. This makes it ideal for applications where a wide coverage area is desired.
Overall, the halo antenna is a versatile and effective option for amateur radio operators looking for a compact and efficient antenna. Each half is about a quarter wavelength long and ends with a current node (zero current and peak voltage) at the break. Halos pick up less ignition noise from engines when mounted on vehicle roofs than whip antennas. They can also be stacked for additional gain and increased efficiency.
However, it’s a challenge to make a 33-foot-long folded dipole for 20 meters in a circular shape for HF use at home. But the circular shape is not necessary—a square version has almost the same properties. This antenna configuration is known as the Squalo (square and halo.) You can apply the same shape and configuration as done with the cobweb, adding additional bands. You want to add 10 meters? Make a 10-meter folded dipole and place it inside the square shape created by the 20-meter dipole.
The square halo is electrically similar to the cobweb in construction and size. If you compare the MFJ-1836 antenna to the Cushcraft ASQ-20, you’ll find both incorporate the half wave folded dipole(s) and a matching transformer. The Squalo maintains its square shape while the cobweb angles the wires to the transformer.
The antenna world is full of dipole variations, and we’ve only looked at a few. If this article piqued your interest, take a look at the OnAllBands article, “Guide to Unusual Ham Radio Antennas” for a discussion of Moxon and Skeleton Slot antennas—close cousins of the halo and hexbeam.
The post Cobweb, Halo, and Hex: Ham Radio Antennas You Can Bend, Wrap, and Fold appeared first on OnAllBands.
I have written about an amazing program called RadioMail in previous articles. This is an application that allows for Winlink mail to be sent and received on an iPhone or iPad. It’s an amazing application for emergency communications use.
That is all well and good, but what if you don’t have a radio with a Terminal Node Controller (TNC)? VARA is a software program that serves as a “sound card TNC” for use with radios. Basically, the TNC translates certain computer files and commands into sounds that are in code. These coded sounds can then be transmitted via RF. On the receiving side, the TNC translates the coded sounds back into computer commands and/or files where they can be used by the receiving computer. The original TNCs were only hardware devices and can still be found on the market.
From RadioMail: VARA is a type of radio software modem that is used for transmitting and receiving digital data over amateur radio. RadioMail interfaces via TCP/IP with such software modem to connect to stations using the VARA protocol. The VARA software modem listens on two ports for commands and data payload.
Using a network protocol like TCP/IP enables the software modem to run on a radio-connected computer, while applications such as RadioMail can operate on a separate device anywhere on the network. However, since VARA wasn’t designed to function as a service, this setup comes with certain limitations, particularly when you don’t have a mouse, keyboard, or display access to the remote computer.
In order to allow for VARA to run on a headless computer, its lifecycle and configuration needs to be manageable entirely remotely.
Varanny is a command line helper tool that steps in to address these limitations, acting as a “nanny” for VARA. It offers the following capabilities:
Questions? Share them in the comments below or email me at KE8FMJ@gmail.com
The post Update to RadioMail—Varanny appeared first on OnAllBands.
In this installment of Ham Mobile Install, we will talk about what happens when you have followed the mobile radio installation instructions to the letter, but there is still something very wrong with the signal.
Noise is a problem that can originate from many different sources when wiring a mobile radio. Noise is often associated with the HF bands, but it isn’t unheard of to have noise issues in VHF/UHF setups. For instance, a common complaint is vehicle alternators and certain engine types causing a whining noise on VHF radios.
Let’s look at just a couple ways hams have dealt with noise problems. If the noise is getting in through the power wires from the car battery to the radio, a quick fix could be adding some ferrite chokes. If there is still an issue, some have suggested coiling the power cable six times to form a two-inch diameter circle, and cable tying it in place. A larger ferrite choke that can fit over the loop of wire would then be added. Chokes can be added to both power cables and coax cables in case the noise is entering by that method.
Others have reported successfully eliminating noise by taking steps to improve the grounding, such as adding a common ground point for the vehicle’s body, hood, exhaust, and radios. This is usually a good practice in general.
RF signals can emanate from your vehicle ignition system, fuel pump, fans, electric motors, onboard computers, and many other sources. Spark plug noise is generated through ungrounded body panels and the exhaust system, which is normally suspended from rubber vibration dampers, as previously noted in OnAllBands. The rubberized supports insulate the exhaust from ground, essentially creating a radiating spark antenna. To deal with spark noise, use tinned copper braid to electrically connect the hood to the firewall of the vehicle. This will turn your hood into a Faraday shield.
Another form of radio interference is loud static. This issue is often found on the HF frequencies, which are more susceptible to static. Bonding straps can be used for the body, hood, and exhaust to take care of a lot of these issues.
Editor’s note: DX Engineering carries a number of products designed to mitigate these mobile radio noise issues:
The post Ham Mobile Install–A Few Suggestions for Dealing with Noise Issues appeared first on OnAllBands.
Finding activity on the ham radio bands used to mean tuning around the dial and listening for QSOs, one frequency at a time. We were blind to anything but the frequency we were on. But now, a useful display tool is appearing on current model radios. Whether you call it a waterfall, band scope, or panadapter, this modern display can show you an overview of the signals present on any radio band.
With waterfall displays, you can instantly tell whether anyone is around. Being able to locate ham radio signals means that you can move quickly to the frequency and give them a call. On some radios, it can be as simple as touching the screen or a mouse click—no need to touch the VFO knob.
The technology has been around for more than 90 years. Panoramic reception was created by a French engineer and ham, Marcell Wallace, F3HM. His panadapter made RF signals visible on a CRT and they could be identified by mode. Early versions like the RBY-1 US Navy Panoramic Radio Adapter were paired with the Hallicrafters SX-28 during WWII.
A radio waterfall display is a graphical representation of a radio signal. It provides a way of visualizing the frequency content of a signal over time and can help radio operators in identifying and analyzing signals easily. On the Icom IC-7610 transceiver, for example, you can select a small range of frequencies or the entire band by adjusting the span.
Typically, the waterfall display appears as a scrolling graph that shows frequency on the horizontal axis. Time can be found on the vertical axis and display speed can be adjusted using <MENU2> on the IC-7610. It features a series of vertical waterfall lines, each representing a snapshot of the signal’s spectrum at a specific moment in time. The most recent snapshot is located at the top of the display, while older snapshots are displayed below it in chronological order.
The default on the IC-7610 is for the centerline to be in the center of the band of the signal, matching the displayed frequency (7.134.00, on the main VFO). Note the numbers at the bottom of the display. The negative numbers moving right indicate decreasing frequency; the positive numbers moving left indicate increasing frequency (see below).
By observing the display over time, an operator can see how the frequency content of the signal changes and can identify patterns in the signal. Starting from the top down, you’ll see the signal amplitude represented in white that is regularly changing. The grayed-out area behind this represents the ghost of signal peaks past, known as peak hold. This spectrum scope is useful for knowing what’s happening on the band this instant.
But there’s additional information the waterfall can tell us. Moving down the screen, look at the waterfall component. Instead of representing signal strength with a graph, you can translate that into a line. New lines are created at the top and then fall downward in real time, just as water does over a waterfall. Speed is adjustable. Sometimes you can find things in the waterfall that don’t show up well on the spectrum scope—maybe some rare DX!
As long as the line is visible, you have time to look back in time. The history shows where conversations have been taking place, and there’s a good chance more could appear as time goes by. This could be useful for finding contacts during contesting—or locating unused frequencies where you can move in and start calling CQ.
You’ll find spots of color with brighter colors on the lines indicating higher signal strength. Waterfall colors are under your control—press and hold the <EXPD/SET> soft button in <MENU1> and the scope set options appear. If you press the <SPAN> button, you can adjust the width of the line or signal trail. Voice modes such as AM and SSB will appear wider than those for digital or CW (see below).
Open spots in the waterfall trail represent several things. They might indicate varying modulation in a transmission, the station got weaker, or it’s a break as the conversation is turned over to another station.
Two can be better than one. There’s a dual panadapter mode that lets you monitor activity on VFO A and VFO B. The example below is from an Elecraft K4D.
Better yet, your radio doesn’t need to have a built-in waterfall display to take advantage of its features. If you’re a digital user, free programs like Fldigi and WSJT-X have built-in waterfall displays to help you navigate the tightly packed signals. Older radios without the waterfall can be used—your computer handles the display.
Yaesu FTXD101 and FTDX10 transceivers offer a 3DSS version of the waterfall. It adds depth to the two-dimensional waterfall. It reminds me of watching an armada of toy sailboats (representing the signal) slowly floating on the Niagara River toward the Falls, then plummeting out of sight.
At lower frequency spans, I’ve found 3DSS is a good way to visualize how much space a signal is taking up and where the peaks are over time. The width and color intensity found on the standard waterfall appear, but it’s a different and perhaps more convenient way to visualize it. Turn down the signal level so the spikes look like individual blades of grass—this will maximize the view of signals (see below).
When there are static crashes, the 3DSS image creates a tall “wall” that makes it hard to see the signals before and after the static crash. Even if you attenuate the level of incoming signals, it still makes the 3D waterfall a challenge to use. That’s when to switch back to the standard waterfall.
The waterfall display can provide a visual representation of complex signals over time, making it a valuable tool for a wide range of applications. You can look for activity on the air, determine the operating mode, and determine signal strength by the clarity and color of the vertical signal trail.
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In this installment of Ham Mobile Install, we will discuss powering options for your mobile radios. There are several options to explore, depending on the power of the transceiver and the amount of time it will be in use without the vehicle running.
The first and easiest option would be for very low power radios—say, handhelds or mini mobiles that top out at 20 to 25 watts. HTs can use their built-in battery or you can purchase a cable that powers the radio from the cigarette lighter. Sometimes these cables plug into the charger port and sometimes they are marketed as battery eliminators. Below is a cigarette lighter cable (KWD-PG-3J) for select Kenwood handheld transceivers.
Mini mobile radios rated at 20 or 25 watts typically come with fused cigarette lighter power cords and are safe to use in your car as they don’t draw too many amps from the cigarette lighter adapter.
The next option is to wire your mobile radio directly to your car battery. Run your transceiver power leads directly to your vehicle battery terminals and avoid any use of existing automobile wiring. The wiring used in most car power outlets is not designed to carry the high currents that a full power transmitter can draw and may quickly overheat and start a fire. In addition, you will probably pick up an abundance of electrical noise going that route.
The power leads will need to be routed through the vehicle’s firewall into the engine compartment and to the battery. In older vehicles, this is much more difficult to do and might require some drilling. Most modern automobiles have access ports through the firewall in different locations. They are usually plugged with a rubber grommet and aren’t always in the most convenient locations. You may have to go searching under the hood and/or under the dashboard. The access ports might even be behind engine components or under carpet or trim.
The last option needs to be considered if you plan on operating from your car for long periods of time while it is stationary. You don’t want your car running for hours, wasting gasoline. You also can’t run for hours on battery power with the car off without depleting your battery.
The thing to do in this case is to have another large battery that can be recharged externally. This battery can be stored most anywhere convenient in the vehicle.
Lithium Iron Phosphate (LiFePO4) batteries, like those from Bioenno Power, have become a reliable energy storage solution for ham radio operations. Unlike traditional batteries, LiFePO4 batteries offer longer lifespans, better thermal stability, and higher energy density, making them ideal for amateur radio where consistent power is crucial.
Questions? Share them in the comments below or email me at KE8FMJ@gmail.com.
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Coax became popular with hams after World War II when war surplus was plentiful. Hams liked it because it was easy to obtain, relatively inexpensive, and easy to install—much easier than ladder line.
We’ve all got some. Whether it’s for cable TV, satellite, Internet, or ham radio, coaxial cable has become the RF highway for moving signals from one point to another. Fortunately, there are no orange barrels or detours—most of the time. But there are occasions when we need to check, repair, or even replace coax.
Materials Needed: Digital voltmeter, jumper with alligator clips and/or SO-239 shorting adapter, dummy load (optional)
The most common and readily available test tool is the digital voltmeter (DVM). Cheaper ones include the basics: voltage, current, continuity, resistance. The more expensive ones add features like capacitance, frequency, amperage, and others. All you need for this checkup are the continuity and resistance settings.
To enter continuity mode, turn the dial to the continuity symbol, which will resemble sound waves or a symbol for a musical note. If you’re using an auto ranging multimeter, you may need to press the “mode” or “select” button a few times until the symbol also appears on your screen.
For testing unconnected patch cords or rolls of coax, touch the multimeter probes on both sides of the cable. Check the shield ends, then the center conductor—if it’s bulk coax without connectors you’ll need to strip the end. If you don’t hear a loud beep, it means there’s a break in the wire or a faulty coax connector.
Stress points on the cable near an antenna rotor or a tight bend can cause the conductor to break, especially with solid wire. Sloppy soldering, or corrosion, on connectors can cause poor connections and problems with your antenna system.
If the cable is already installed, make sure to disconnect it from your radio and antenna—below any matching devices. Things like baluns, ununs, and chokes can cause false readings. For example, a 4:1 balun can read as a DC short on a DVM but operate properly at radio frequencies.
It’s a pain to check a 100-foot coax run that’s already in place—the meter test leads aren’t long enough. Instead, check the cable for an existing short by touching one probe to the center pin and one to the outside of the PL-259 connector at one of the ends. If there’s no beep indicating a short, make it a single conductor by tying together one end, connecting the center pin and outside of connector. The alligator clip jumper will work, but I prefer using a panel mount SO-239 with the center grounded to the pin.
Touch both leads at the remaining end with the DVM leads. If you hear the beep, both shield and center conductor are okay. If not, check your connectors for issues or consider replacing the entire run.
Some prefer to use a similar method with the resistance scale and a 50-ohm dummy load, which substitutes for your antenna. No dummy load? You can use a 47-ohm resistor, which is close enough. When you touch the leads, the 0L reading should change to something in the ballpark of 50 ohms if the coax is okay.
In the next section, you’ll see how to check the cable’s integrity. Sections of the coax you replaced could test okay and possibly be recycled to make jumpers or short runs.
Materials Needed: Antenna analyzer, coax connector or alligator clip jumper to short the end of cable, velocity factor (VF) numbers for cable(s) you’re testing. Velocity factor can be found at the dealer or manufacturer website.
Most hams use antenna analyzers while building and tuning antennas, but it has other features that will help you measure coax length without a tape measure, calculate loss in dB, and discover its general condition. The examples that follow are based on one popular model, the RigExpert AA-55Zoom, measuring DX Engineering RG-8X 50-ohm Coaxial Cable (DXE-8X). Consult your specific analyzer’s instructions for operation.
Got some coax but no tape measure? Let your antenna analyzer do the work. On the AA-55, select TOOLS from the menu, then LENGTH & VF. Enter the velocity factor and press OK. Length will appear on the screen in the format you’ve selected (feet or meters).
You can also find velocity factor by entering a known length. The photo below shows the length of a patch cable I randomly selected, calculated by the AA-55.
The greater the length of coax cable you use, the more signal loss you will have. This is due to a number of factors. Losses within the coax cable itself come from the resistance of the conductors. Dielectric loss represents another of the major losses in most coax cables—the dielectric is the insulation around the center conductor. The loss increases with frequency.
Radiated loss of a coax cable is normally much less than the resistive and dielectric losses. But some very cheap coax cables may have a very poor outer braid, and in these cases will contribute to additional losses.
To find how much attenuation there is in a length of cable, go to the TOOLS MENU and choose CABLE LOSS. You’ll take two measurements, the first with the cable end open and the second with the end shorted. The AA-55 will collect the data and show a graph (below) of the losses in dB. You can change the frequency by moving the left/right arrows.
The loss graph shows 1.46 dB attenuation for the 150-foot test cable at 7.150 MHz, which has seen plenty of action at Field Days and Ohio State Parks on the Air (OSPOTA) activations.
To find the impedance in a length of cable, go to the TOOLS MENU and choose CABLE IMPEDANCE. You’ll take two measurements, the first with the cable end open and the second with the end shorted. The AA-55 will collect the data from 100KHz to the maximum frequency on your analyzer and show a graph (below) of the impedance at any given frequency. You can change the frequency by moving the left/right arrows. You’ll notice in this case, it’s very close to the 50-ohm specs.
This can help you identify unmarked coax as well as check compliance with the coax specs provided by the manufacturer. It’s also a way to monitor coax condition from season to season. As the sun bakes our coax installed outdoors, impedance and losses will change over time due to exposure.
It’s not practical to peel back the jacket and shield to examine a length of coax—it would render the cable useless. But tools like the DVM and antenna analyzer will let you check and assess the viability of your coaxial cable electronically to help you make decisions about repairing or replacing.
The post How to Test Coaxial Cable appeared first on OnAllBands.
In this installment of Ham Mobile Install, it’s all about mounting options for your mobile radio—the where and how of making sure the transceiver or head is in a place good for viewing and operating. Steady and secure are the objectives.
While there are plenty of brands out there, none are better than Lido Mounts, in my opinion. Lido offers no-holes mounting solutions for any type of radio. You can choose from gooseneck, cup holder, seat-bolt-style, suction cup, vent, and other mount options; seat rails for remote heads; microphone hangers; adapters; and additional accessories.
The most basic type of radio in your mobile setup would be an HT. When choosing a mount, ask yourself how you would like to view the HT while driving. With or without a mic, you could do a dashboard mount or a vent mount. You could have that same dashboard mount hold multiple portable handhelds. Another very popular option is the cup holder mount.
Lido cup holder mounts can handle multiple devices with not much movement. The design is based on the 1-inch ball system. The ball and socket design allows the user to tighten the plate in place so it will not move with any vibration. The base expands from 2 1/2 to 3 1/2 inches in diameter so it will fit many types of cup holders. Make it a double, as shown above, and you can add your cell phone right beside it!
For my Jeep, one of my very favorite mounts is the Lido Wedge Car Seat Console Mount (LM-WEDGE). The adjustable wedge-style mount fits in the space between your front seat and the console. It features a Robust Mount Series shaft and padded sides that keep the mount in place. The arm of the mount includes two adjustment points, providing flexibility in placing the control head at any angle, including toward the back seat.
You can attach optional remote head brackets with the included hardware, or if you want to mount the entire transceiver, you can attach the mounting brackets that are made for the transceiver to the four-hole AMPS plate with the included hardware. The LM-WEDGE comes with the Lido EXT-01-D Extension Bracket Package.
For weightier heads and radios, there are more robust mounting solutions, such as Lido’s Heavy-Duty Seat Bolt Mounts.
These low-vibration mounts hold heavier control heads with little movement and can be folded out of the way to accommodate passengers. The swivel ball adapter allows 360 degrees of rotation for precise positioning of your device.
Happy mobile radioing!
Questions? Share them in the comments below or email me at KE8FMJ@gmail.com
The post Ham Mobile Install–Mounting Your Radio appeared first on OnAllBands.
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