Maintenance tools

Maintenance involves taking care of all your equipment, as well as fabricating any necessary cables or fixtures to put it together. Figure 15-1 shows a good set of maintenance tools.

Having these tools on hand allows you to perform almost any electronics maintenance task:

• Wire cutters: Use a heavy-duty pair to handle big wires and cables, and a very sharp pair of diagonal cutters, or dikes, with pointed ends to handle the small jobs.
• Soldering iron and gun: You need a small soldering station with adjustable temperature and interchangeable tips. Delicate connectors and printed-circuit boards need a low-temperature, fine-point tip. Heavier wiring jobs take more heat and a bigger tip. A soldering gun should have at least 100 watts of power for antenna and cable soldering. Don’t try to use a soldering gun on small jobs or circuit boards.
• Terminal crimpers: Use a real crimper, not pliers — they are not expensive. There are lots of YouTube videos showing how to install crimp terminals (see Figure 15-2) and do the job right the first time. Also use the right terminal size for the wire you’ll be attaching it to.
• Head-mounted magnifier: Electronic components are getting smaller by the hour, so do your eyes a favor. Magnifiers are often available at craft stores. You can also find clamp-mounted, swing-arm magnifier/light combinations.
• Digital multimeter (DMM): Even inexpensive models include diode and transistor checking, a continuity tester, and maybe a capacitance and inductance checker. Some models also include a frequency counter, which can come in handy.

Electronic kit vendors offer inexpensive “learn to solder” kits. If you haven’t soldered before, these are a great way to learn. Most come with an simple soldering iron, too, but you should upgrade to a soldering station as soon as you begin regularly working on electronics.

Electronic components can be damaged by static electricity, such as when a spark jumps from your finger to a doorknob — a phenomenon called ESD (for electrostatic discharge). Inexpensive accessories for controlling ESD at your workplace and draining the static from your skin are available from electronic kit and parts vendors.

You also need to have spare parts on hand. Start by having a spare for all your equipment’s connectors. Look over each piece of gear and note what type of connector is required. When you’re done, head down to the local electronics emporium and pick up one or two of each type. To make up coaxial cables, you need to have a few RF connectors of the common types shown in Figure 15-3. UHF, BNC, and N. SMA connectors, common on the newer handheld radios, take special tools to install. You’ll purchase cables with SMA connectors already installed or adapters, as described next.

Figure 15-4 shows many of the common power connectors used for radios and accessories. Power connectors have large pins and sockets or surfaces to carry the necessary current with low resistance. The audio and data connectors in Figure 15-5 are much smaller. They don’t need to carry large currents so the contacts are smaller and more closely spaced.

You often need adapters when you don’t have just the right cable or a new accessory has a different type of connector. Table 15-1 shows the most common adapter types. You don’t have to get them all at once, but this list is good to take to a hamfest or to use when you need an extra part to make up a minimum order.

A plug is the connector that goes on the end of a cable. A jack is the connector that’s mounted on equipment. A male connector is one in which the signal contacts are exposed pins (disregard the outer shroud or shell). A female connector has recessed sockets that accept male connector pins.

Along with adapters and spare parts, you should have on hand some common consumable parts:

• Fuses: Have spares for all the fuse sizes and styles your equipment uses. Never replace a fuse with a higher-value fuse.
• Electrical tape: Use high-quality tape such as Scotch 33+ for important jobs, such as outdoor connector sealing, and get the cheap stuff for temporary or throwaway jobs.
• Fasteners: Purchase a parts-cabinet assortment with No. 4 through No. 10 screws, nuts, and lockwashers. Some equipment may require the smaller metric-size fasteners. You need ¼-inch and -inch hardware for antennas and masts.

Keep a list of what materials and components that are running low so that when you start shopping online, head for the store, or go to a hamfest or flea market you won’t forget what you need. This also helps you avoid buying unnecessary duplicate items.

Cleaning equipment is an important part of maintenance, and you need the following items:

• Soft-bristle brushes: Old paintbrushes (small ones) and toothbrushes are great cleaning tools. I also keep a round brush for getting inside tubes and holes.
• Metal bristle brushes: Light-duty steel and brass brushes clean up oxide and corrosion. Brass brushes don’t scratch metal connectors but do damage plastic knobs or displays. Don’t forget to clean corrosion or grease off a brush after the job.
• Solvents and sprays: I keep on hand bottles or cans of lighter fluid, isopropyl alcohol, contact cleaner, and compressed air. Lighter fluid cleans panels and cabinets gently and quickly, and also removes old adhesive and tape. Always test a solvent on a hidden part of a plastic piece before applying a larger quantity.

If you would like more information about building electronic circuits and working with electronic components, check out Circuitbuilding For Dummies by the author.

Repair and building tools

Figure 15-6 shows additional hand tools that you need when you begin doing your own repair work or building equipment. (The figure doesn’t show larger tools such as a drill and bench vise.)

Repairing and building go beyond maintenance in that you work with metal and plastic materials. You also need some additional specialty tools and instruments for making adjustments and measurements:

• Wattmeter or SWR meter: When troubleshooting a transmitter, you need an independent power-measurement device. Many inexpensive models work fairly well (stay away from those in the CB shops; they often aren’t calibrated properly when not used on CB frequencies). If you do a lot of testing, the Bird Model 43 is the gold standard in ham radio. Different elements, or slugs, are used at different power levels and frequencies. Both used meters and elements are available online and at hamfests.
• RF and audio generators and oscilloscope: Although you can do a lot with a voltmeter, radio is mostly about RF and audio waveforms so you need a way to generate and view them. If you’re serious about getting started in electronics, go to www.arrl.org/servicing-equipment to read up on techniques and test equipment for working on radio equipment.
• Nibbling tool, stepped drill bit, and chassis punch: Starting with a round hole, the nibbler is a hand-operated punch that bites out a small rectangle of sheet metal or plastic. Use a nibbler to make a large rectangular or irregular opening and then file the hole to shape. The stepped drill bit (for smaller holes) creates a variety of hole sizes in sheet metal and plastic. A a chassis punch (for big holes) makes a clean hole in up to ⅛-inch aluminum or 20-gauge steel. Chassis punches aren’t cheap, but if you plan to build regularly, they can save you an enormous amount of time and greatly increase the quality of your work.
• T-handled reamer and countersink: The reamer allows you to enlarge a small hole to a precise fit. A countersink quickly smooths a drilled hole’s edges and removes burrs.

Drilling a hole in a panel or chassis that already has wiring or electronics mounted on or near it calls for special measures. You must prevent metal chips from falling into the equipment and keep the drill from penetrating too far. To control chips, put a few layers of masking tape on the side of the panel where you’re drilling, with the outer layers kept loose to act as a safety net. To keep a drill bit from punching down into the wiring, place a small piece of hollow tubing over the bit, exposing just enough length to penetrate all the way through.

Components for repairs and building

I find myself using the same components in the following list for most building and repair projects. Stock up on these items (assortments are available from component sellers), and you’ll always have what you need:

• Resistors: Various values of 5 percent metal or carbon film, ¼- and ½-watt fixed-value resistors; 100, 500, 1k, 5k, 10k, and 100k ohm variable resistors and controls
• Capacitors: 0.001, 0.01, and 0.1 μF ceramic; 1, 10, and 100 μF tantalum or electrolytic; 1000 and 10000 μF electrolytic; miscellaneous values between 220 pF and 0.01 μF film or ceramic
• Inductors: 100 and 500 μH, and 1, 10, and 100 mH chokes
• Semiconductors: 1N4148, 1N4001, 1N4007, and full-wave bridge rectifiers; 2N2222, 2N3904, and 2N3906 switching transistors; 2N7000 and IRF510 FETs; red and green LEDs
• ICs: 7805, 7812, 78L05, and 78L12 voltage regulators; LM741, LM358, and LM324 op-amps; LM555 timer; LM386 audio amplifier

There are two basic types of components: through-hole and surface-mount. Through-hole parts have wire or stamped metal leads that go through holes (thus the name) in a circuit board and are soldered to pads on the circuit-board. Surface-mount devices (SMD), or surface-mount technology (SMT) components, have metal contacts on their surface. The component is placed on a pad with some solder paste and the whole assembly heated until the solder melts, attaching the component to the pad. Through-hole components are a lot easier for human hands (and eyes) to work with, but SMD components are becoming the norm for electronics. Learning how to work with both is a good idea.

Although having a completely stocked shop is nice, you’ll find that building up the kinds of components you need takes time. Rather than give you a huge shopping list, I give you some guidelines to follow:

• When you buy or order components for a project, order extras. The smallest components — such as resistors, capacitors, transistors, and diodes — are often cheaper if you buy in quantities of ten or more. After a few projects, you have a nice collection.
• Hamfests are excellent sources of parts and component bargains. Switches and other complex parts are particularly good deals. Parts drawers and cabinets often come with parts in them, and you can use both.
• Broken appliances and entertainment devices around the home are worth stripping before throwing out. Power cords and transformers, headphone and speaker jacks, switches, and lots and lots of other interesting hardware items end up in the dump. Also, seeing how these items are made is interesting.
• Build up a hardware junk box by tossing in any loose screws, nuts, spacers, springs, and so on. Use an old paint tray or a flat open tray to make it easy to root through the heap in search of a certain part. The junk box can be a real time and money saver.

Sporting-goods and craft stores have frequent sales on inexpensive tackle boxes and multiple-drawer cases that are perfect for electronic components. ICs and transistors should be kept in aluminum foil or static-dissipating bags to prevent damage from static electricity, called ESD for electro-static discharge.

To get experience working with electronics, build some kits! The instructions help you get the kit built and working. You gain experience with how electronic devices are made and in handling components. Plus, you get a working piece of electronics that you made yourself. See the section on building kits later in this chapter.

Power problems

Power problems can be obvious (no power), spectacular (failure of the high-voltage power supply), or subtle (AC ripple, slightly low or high voltage, or poor connections). The key is to never take power for granted. Just because the power supply light is on doesn’t mean the output is at the right voltage. I’ve wasted a lot of time due to not checking power, and now I always check the power supplies first. Try these tests to find power problems:

• Check to see whether the problem is caused by the equipment, not the power supply. You can easily isolate obvious and spectacular failures, but don’t swap in another supply until you’re sure that the problem is, in fact, the power supply. Connecting a power supply to a shorted cable or input can quickly destroy the supply’s output circuits. If a circuit breaker keeps tripping or fuse keeps opening, don’t jumper it. Find out why it’s opening.
• Check for low output voltage. Low voltage, especially when transmitting, can cause radios to exhibit all sorts of strange behavior. The microprocessor may not function correctly, leading to bizarre displays, loss of external control, and incorrect responses to controls. Low voltage can also result in low power output or poor RF stability (chirpy, drifting, or raspy signals). Check with the supply disconnected and with a light load. Remember that “12 volt” radios usually need 13.8 V or so to really work properly.
• Check the supply output using both AC and DC meter ranges. Ripple on your signal can mean a failing power supply or battery. A DC voltmeter check may be just fine, but power supply outputs need to show less than 100 mV of AC. Watch for intermittent or erratic voltages that indicate voltage regulation or internal connection problems.
• If you suspect a poor connection, measure voltage at the load (such as the radio) and work your way back to the supply. Poor connections in a cable or connector cause the voltage to drop under load. They can be difficult to isolate because they’re a problem only with high current, such as when you’re transmitting. Voltage may be fine when you’re just receiving. Excessive indicator-light dimming is a sure indicator of poor connections or a failing power supply.

Working on AC line-powered and 50-volt or higher supplies can be dangerous. Follow safety rules, and get help if you’re unsure of your abilities.

If your USB device is powered from the USB host, be sure that the host can supply power at the required amount of current. Remember that portable USB hubs often don’t supply power unless connected to an AC adapter. Similarly, a laptop may be configured not to supply USB power unless its battery charger is working.

RF problems

Some RF problems occur when RF isn’t going where it’s supposed to go. These problems generally are caused by a bad or missing cable, connector, or switching device (a switch or relay) that needs to be replaced. Try fixing these problems with the following suggestions:

• Replace cables and adapters one at a time, if you have spares that you know work.
• Note which combinations of switching devices and antennas seem to work and which don’t. See whether the problem is common to a set or piece of equipment or specific cables.
• Bypass or remove switches, relays, or filters. Make a note in the station notebook to put the device back in and put a label or sticky note on the equipment to remind you of the change.
• Check through antenna feed lines. Take into account whether the antenna feed point has a DC connection across it, such as a tuning network or impedance-matching transformer. Gamma-matched Yagi beams show an open circuit, whereas beta-matched Yagis and quad loops have a few ohms of resistance across the feedpoint. (Note: Recording the normal value of such resistances in the station notebook for comparison when troubleshooting is a good idea.)

Other problems you may come across include “RF hot” microphones and equipment enclosures, and interference to computers or accessories. (You haven’t fully lived until you get a little RF burn on your lip from a metal microphone!) Usually, you can fix these problems by bonding equipment together (see Chapter 13). Try these suggestions:

• Double-check to ensure that the equipment is connected to the station RF ground bus. The equipment may be connected, but double-checking never hurts.
• Check the shield connections on audio or control cables. These cables are often fragile and can break when flexed or yanked. (You never yank cables, do you?)
• Coil up an excessively long cable or swap in a shorter one.
• Add ferrite RF suppression cores to the cables (see the “Ferrites as RFI suppressors” sidebar, later in this chapter).

On the higher HF bands (particularly 21, 24, and 28 MHz), cables and wires begin to look like antennas as their lengths exceed ⅛ wavelength. A 6-foot data cable, for example, is about wavelength long on 28 MHz and can have a sizable RF voltage at the midpoint, even though both ends are connected to equipment enclosures. If you have RF pickup problems on just one band, try attaching a ¼-wavelength counterpoise wire to move the RF hot spot away from the equipment in question. A ¼-wavelength wire left unconnected at one end can act like a short-circuit at the other end. Attaching the counterpoise to the enclosure of the affected equipment may lower the RF voltage enough to reduce or eliminate the interference. Keep the wire insulated and away from people and equipment at the unconnected end.

Operational problems

Operational problems fall into three categories: power, data, and control. After you determine which type of problem you have, you often come very close to identifying the cause of the problem.

Dealing with interference to other equipment

Start by making your own home interference-free. Unless you’re a low-power VHF/UHF operator, you likely own at least one appliance that reacts to your transmissions by buzzing, humming, clicking, or doing its best duck imitation when you’re speaking. It’s acting like a very unselective AM receiver, and your strong signal is being converted to audio, just like the old crystal radio sets did. It’s not the ham radio’s fault — the appliance is failing to reject your signal — but it’s still annoying.

Your goal is to keep your signal out of the appliance so that it doesn’t receive the signal. Sounds simple, doesn’t it? Start by removing all accessory cords and wires to see whether the problem goes away. If it does, put the cords and wires back one at a time to see which one is acting as the antenna. Power cords and speaker leads are very good antennas and often conduct the RF into the appliance. Wind candidate cables onto a ferrite interference suppression core (see the sidebar “Ferrites as RFI suppressors”) close to the appliance to find out whether that cures the problem. You may have to add cores to more than one of the leads, although generally just one or two are sensitive. You can buy component-level Corcom AC line filters from most distributors and MFJ makes AC line filters, as well.

If the device is battery-powered and doesn’t have any leads, you probably can’t fix the problem, I’m sorry to say. You either have to replace the device or get along with the interference. The manufacturer’s website may have some interference cures, or you may find some guidance from ham radio websites or club members. Try searching for the model number of the appliance and interference or RFI to see what turns up.

The stored messages in the archives of the RFI email reflector (www.contesting.com/FAQ/rfi) are good sources of information. You don’t have to be a member of the reflector to read them. Start by searching for messages about the type of device you’re having trouble with. If you find information about it, narrow your search with additional terms.

The following common devices are often victims of interference:

• Cordless telephones: Older phones that use 47 MHz frequencies are often devastatingly sensitive to strong signals. Luckily, newer phones use 900 MHz and 2.4 or 5.6 GHz radio links and are much less sensitive to your RF. If you come up against one of the 47 MHz units, just replace it with a newer one.
• Touch lamps: These accursed devices respond to nearly any strong signal on any frequency. You can try ferrite cores on the power cord, but results are definitely mixed. Internal modifications are described on the ARRL RFI website. Replacing the lamp may be the easiest option.
• TV, video, and audio equipment: A common path for interference is via the speaker wires, but any of the many connections among pieces of equipment can be picking up RF. Make sure that all the equipment ground terminals are connected by short, stout wires. The ARRL’s RFI website is probably your next stop.
• Alarm systems: The many feet of wire strung around the house to the various sensors and switches create a dandy antenna. Unfortunately, the system controller sometimes confuses the RF that these wires pick up for a sensor signal. System installers have factory-recommended interference suppression kits that take care of most problems.

By practicing on your own home electronics, you gain valuable experience in diagnosing and fixing interference problems. Also, if a neighbor has problems, you’re prepared to deal with the issue. See the nearby sidebar, “Part 15 devices.”

Dealing with interference to your equipment

Two noise sources are likely to cause interference: electric and electronic. Electric noise is caused primarily by arcing in power lines or equipment, such as motors, heaters, and electric fences. Electronic noise is caused by leaking RF signals from consumer appliances and computers operating nearby. Each type has a distinctive signature, or characteristic sound. The following list describes the signatures of common sources of electric noise:

• Power line: Steady or intermittent buzzing at 60 Hz or 120 Hz. The weather may affect interference.

  Power-line noise is caused by arcing or corona discharge. Arcing can occur around or even inside cracked or dirty insulators. It can also occur when two wires, such as neutral and ground wires, rub together. Corona discharge occurs at high-voltage points on sharp objects where the air molecules become ionized and electricity leaks into the atmosphere. The interference is a 120 Hz buzzing noise because the arc or discharge occurs at the peaks of the 60 Hz voltage, which occur twice per cycle.

  Do not attempt to fix problems with power lines or power poles. Always call your power company.

  You can assist the power company by locating the faulty equipment. You can track down the noise source with a battery-powered AM radio or VHF/UHF handheld radio with an AM mode (aircraft band works well). If you have a rotatable antenna at home, use it to pinpoint the direction of the noise. (The null off the side of a beam antenna is sharper than the peak of the pattern.) Walk or drive along the power lines in that direction to see whether you can find a location where the noise peaks. I’ve found several power poles with bad hardware by driving around with the car’s AM radio tuned between stations. If you do find a suspect pole, write down any identifying numbers on the pole. Several numbers for the different companies that use the pole may be on it; write them all down. Contact your utility and ask to report interference. You can find a great deal more information about this process on the ARRL RFI web page (www.arrl.org/radio-frequency-interference-rfi).

• Industrial equipment: Sounds like power-line noise but with a more regular pattern, such as motors or heaters that operate on a cycle. Examples in the home include vacuum cleaners, furnace fans, and sewing machines.
• Defective contacts: Highly erratic buzzes and rasps, emitted by failing thermostats or switches carrying heavy loads. These problems are significant fire hazards in the home, and you need to fix them immediately.
• Dimmers, electronic ballasts, and variable-frequency speed controls: Low-level noise like power lines that comes and goes as you use lights or motors. Variable-frequency drive (VFD) systems in large appliances can generate a lot of noise that is present when the appliance is operating.
• Switching power supplies: Miniature power supplies that mount directly on the AC outlet (called wall warts) use rapidly switching electronics to convert AC power to low-voltage DC. They are used for low-voltage lighting and all sorts of appliances, computer equipment, and phone chargers. Although these devices are efficient, they can be real noisemakers. Sometimes, a ferrite core on the DC output helps, but the best solution is to replace the supply with a regular linear supply that uses a transformer.
• Battery chargers: These sometimes use switching electronics, too, and they’re much harder to fix or replace. You can often get relief by turning them off or unplugging them when the batteries are fully charged.
• Vehicle ignition noise: Buzzing that varies with engine speed, which is caused by arcing in the ignition system.
• Electric fences: Regular pop-pop-pop noises at about 1-second intervals. A defective charger can cause these problems, but the noise is usually caused by broken or missing insulators or arcing from the fence wires to weeds, brush, or ground.

Finding an in-home source of electric noise depends on whether the device is in your home or a neighbor’s. Tracking down in-home sources can be as simple as recognizing the pattern when the noise is present and recognizing it as the pattern of use for an appliance. You can also turn off your home’s circuit breakers one at a time to find the circuit powering the device. Then check each device on that circuit.

Battery-powered equipment may not turn completely off via the power switch if internal control circuits are still on in a low-power state. You may have to physically disconnect or remove the batteries to be sure the device is off. If the noise is coming from outside your home, you have to identify the direction and then start walking or driving with a portable receiver. Review the ARRL RFI website or reference texts for information about how to proceed when the interfering device is on someone else’s property.

What about electronic noise? The following list describes the signatures of common sources of electronic noise:

• Computers, videogame consoles, and networks: These devices produce steady or warbling tones on a single frequency that are strongest on HF, but you can also hear them at VHF and UHF.
• Cable and power-line modems: You hear steady or warbling tones or hissing/rasping on the HF bands.
• Cable TV leakage: Cable TV signal leakage at VHF and UHF sounds like hissing noise. Cable channel 12 covers the same frequencies as the 2 meter band. If you have leakage, a strong ham signal can also cause interference on the same channel.
• Plasma TVs: Although a few models are RF-quiet, many generate noise across a wide spectrum of frequencies. The only solution seems to be to replace them with LCD or LED models, which don’t have the noise problem. Plasma TVs are gradually being retired as they wear out.

Each type of electronic interference calls for its own set of techniques for finding the source and stopping the unwanted transmission. You’re most likely to receive interference from devices in your own home or close by because the signals are weak. If you’re sure that the source isn’t on your property, you need a portable receiver that can hear the interfering signal.

The ARRL RFI website has some helpful hints on each type of interference, as well as guidance on how to diplomatically address the problem (because it’s not your device). The Overview page of the ARRL RFI website contains excellent material on dealing with and managing interference complaints (both by you and from others). ARRL members have access to the league’s technical coordinators and technical information services.

You can eliminate or reduce most types of interference to insignificant levels with careful investigative work and application of the proper interference-suppression techniques. The important thing is to keep frustration in check and work the problem through.