With all the storms that pounded us this winter, now is the time to check your antennas for wear and damage. How do you check for problems and where do you get the parts to repair and upgrade your antenna farm?
Wire Antennas
Question: How long should an antenna stay up? Answer: Only until it falls down, of course! Wire antennas don’t last forever—installation and quality of components are significant factors for increasing their useful life. The goal is to minimize major letdowns.
What about wire? Should you go with steel, copper or aluminum? Solid or stranded? Bare or insulated? Actually, the wire used has only a small effect on the radiated signal strength. However, solid wire is more likely to become brittle due to flexing in the wind, and more prone to break sooner than an equivalent stranded wire would. For ease of handling, many hams choose stranded PVC insulated wire.
DX Engineering Premium Antenna Wire is sturdy enough for replacement or new installations. This PVC-insulated, 14 AWG stranded copper wire consists of 19 strands of 27 AWG solid copper. Its PVC insulation is UV-resistant and rolls out easily without kinks. If placed under extreme stress, DX Engineering Premium wire will stretch before breaking.
When determining how much wire you need, remember to measure twice, add a little extra to cover mistakes, and order once.
Supporting Cast
You need to check out the entire length of all support ropes for wear, including guys and antenna support lines. This is especially true for ropes that contact tree limbs or any place that can cause abrasion. Also, remember that squirrels and other critters like to chew on ropes.
Compare your support rope with a piece of the same rope that has not been in the sun and weather. Note how quickly the material is deteriorating. Does it feel stiffer? Does its color look dull and weathered? Are strands breaking? If so, consider replacing them. Stick with ropes that are UV-protected for extended longevity. Mastrant and Synthetic Textile Industries ropes are made from Dacron, polypropylene, polyester or a combination of these for strength and UV resistance.
Suggested installation includes supporting the feed point to properly handle the weight of the feedline and balun (if used) so that the wires only need to support themselves. Ideally, the support should be a tree, insulated pole, or tower with an insulated standoff. If the antenna layout can’t accommodate a center support, add a messenger line—a rope stretched tight between two supports, such as trees, to hold up the center and minimize stress on the antenna wires.
If the antenna is hung between two trees, a “shock absorber” is needed to prevent the antenna from tearing due to swaying of the trees in windy conditions. The simplest solution is to use elastic material such as bungee cords or door springs on the ends of the support rope. Springs are usually more durable, but a good quality bungee cord will last for a few years. Provide fall protection with a short rope attached across the spring or elastic cord in case either breaks.
Insulators
The ends of wire antennas are high voltage points, and insulators are intended to isolate the voltage from coming into contact with other objects. Insulators can also ensure your antenna isn’t detuned if the element comes into electrical contact with wet ropes, etc. Antenna insulators are typically made from plastic, ceramic, porcelain or glass.
Remove the dirt and other accumulated gunk off the insulators. Replace if they are cracked. One particularly ingenious solution is DX Engineering Wire Antenna End Insulators. They feature a serpentine wire grip for insulated antenna wires with no need for soldering or crimping. This allows for fast and easy antenna length adjustments.
Center insulators isolate the two elements in a common dipole, act as a feed point connection, and may also be part of a balun/unun. These also deserve close inspection for cracks, broken or corroded connections, balun eye-bolt damage, or water inside the balun enclosure. Repair, drain or replace as necessary, and weatherproof any electrical connections.
Aluminum and Fiberglass Antennas
Verticals and Yagis commonly use aluminum tubing for constructing radiating elements. Though they’re lightweight and sturdy, they can be bent, or worse, by strong winds. The director element on my tri-bander was ripped from the boom during a particularly intense windstorm. I found it stuck in the ground like a giant aluminum javelin. The end element was badly bent and the trap behind it had a shattered insulator and bent trap cover.
This is a case where you need to contact the antenna manufacturer or dealer for replacement parts. This trap was a specialty item, specific to the brand of antenna, but the aluminum tubing was readily available at DX Engineering. Be sure to confirm the proper measurements, OD and wall thickness using a caliper. These pieces tend to have close tolerances for a tight fit.
Other antenna components such as clamps, hardware, adapters and other items can also be obtained through DX Engineering, as well as replacement parts for Hustler and Butternut antennas. And don’t forget anti-seize when replacing tubing and hardware.
Cobweb, spider, and hex antennas utilize fiberglass poles as spreaders in their construction. They’re lightweight and fairly sturdy, but UV will degrade the fiberglass if not protected. Broken or cracked pieces should be replaced. To help prevent or slow down UV damage, spray the fiberglass poles with clearacrylic or acrylic in the color of your choice.
Another suggestion is to guy your antennas to prevent some of these problems. Often, your antenna manual will have specific recommendations.
Coax Deterioration
Just because a cable looks okay doesn’t mean it is. Damage is sometimes invisible to the naked eye. You can usually depend on coaxial cable used in ham radio applications to last 10 to 15 years—maybe more depending on the quality of the cable. Damage from rough or improper handling and accidents are the most common types of damage, along with UV and water ingress.
The connector on either end can also go bad, whether it is BNC, SO-239, or some other type. Sometimes the damage will be obvious, like a missing center pin. Sometimes it will be hard to see, like if the solder has come loose behind the connector or the connection was improperly performed in the first place.
Cut the coax a few inches from the old connector to remove it and prep the coax for a new connector. If the wire and shield show no obvious corrosion, install a new connector and check the integrity of the connections. Attach the connector to the antenna and seal it with Temflex and electrical tape to keep water from getting into the connection and corroding it.
If you want to do more than a visual inspection, disconnect the coax from the antenna and measure the coax for power loss. Put a dummy load at the antenna end of the coax. Measure the transmitter output power, using an accurate wattmeter placed at the transmitter end of the coax. Next, move the wattmeter to the dummy load end of the coax and install it there. Reconnect the coax to the transmitter without changing any of the transmitter’s settings, and measure the power delivered to the dummy load. Compare the two numbers and determine the loss of power through the coax. If the measured value is not within a few percent of the cable’s loss specifications, replace the coax.
Avoid Future Problems
Sometimes it’s impossible to prevent unexpected damage to your antennas. But for those things you can control, prevention is the best medicine. Guys, weather seals, and coatings should be part of your regular installation and maintenance routine. When you make a repair or upgrade, be sure to use the best materials you can and protect your antenna system from corrosion and weathering.
