Read the instructions! Read the instructions again! Then, follow the instructions! Explicitly! If you're still having problems, read the instructions, yet again!
If there is one common factor with respect to antenna problems, it's failure to read and follow the instructions which came with the product(s). This should be done prior to any hardware installation, especially antennas! What's more, most ancillary equipment require that a specific setup procedure be followed. When they're not, exasperation and angst are the typical result. This is especially true of automatic antenna controllers.
The most common problems encountered are listed below, more or less in order. However, read the whole article, not just one section. The reason is simply this; some problems appear to be, or are manifested as, another problem altogether. Thus making assumptions of what your specific problem is, will get you into as much trouble as not reading the instructions in the first place.
Whatever the problem, it can be always be solved. Sometimes solving the problem requires a complete change in the architecture. For example, some mounting techniques are bound for failure. Lip mounts are the prime example. Designed to attach to trunk lids, hatches, or doors, every time they're opened or shut, stress is put on both the antenna and mount. Sooner or later, the mount loosens. Adding insult, users sand the paint and zinc undercoat to bare metal which accelerates rusting, and accelerates the failure rate.
Digressing. In case you missed the point, sanding the finish on modern vehicles to bare metal, will eventually cause what little connection there is, to fail completely.
Here are a few things to keep in mind. If the chosen mount requires no holes, or uses set screws to hold it on, it will fail in time (typically short). Ground straps are not a cure all for these poor mounting techniques. Even the lightest of HF antennas will stress their mounts when attached to trunks, hatches, or doors. Abbreviated mounts always add to ground losses, which increases the likelihood of common mode currents, which in-turn increases RFI.
A lot of folk use lip mounts to circumvent drilling holes. Click on the right photo, and take a look at what lip mounts do to sheet metal. The antenna in question is a Yaesu ATAS-120, one of the lossiest antennas money can buy! The coax feed is also the motor control cable. Depending on the voltage supplied to the antenna, it either extends or retracts. Since there is no provision for installing a choke on the coax cable to minimize common mode currents, owners often experience tuning problems, which are exacerbated by the clip mount usually employed. The problem is so pervasive, there is even a paragraph in the ATAS-120's Owner's Manual about it.
Digressing again. Without doubt, short, stubby antennas (including the High Sierra Sidekick®, and Lil Tarheel®), mounted atop lip mounts, are the most pervasive problem faced by neophyte mobile operators. If this is the type of antenna you're using, do yourself a favor, and pay particular attention to the next two sections.
My Remote Antenna Controller Won't Work
The biggest single issue which causes remote antenna controllers not to function properly is RFI getting into the logic circuitry. There are two main RFI avenues; The motor leads (and reed switch leads if used), and the coax cable.
The motor (and the reed switch) leads of remotely controlled HF antennas operate above RF ground. Therefore, they must be choked! With one exception, the manufacturers' supplied motor lead chokes are wholly inadequate for the purpose.
The requisite choke must have an impedance at least two magnitudes higher than the antenna's impedance. In other words, greater than 5,000 ohms. If you're using a stubby antenna and/or a poor mounting technique (a lip mount for example), the choke may need to be two, perhaps three times as large (10,000 to 15,000 ohms!).
These chokes must be as close to the antenna as possible. This negates mounting them inside the vehicle, or next to the controller. Remember! All of the wire before the choke is part of the antenna, and must be kept outside the vehicle. If you do not, RF can be induced into the vehicle's wiring, causing great grief and frustration. Again, this article explains how to properly wind the chokes.
Common mode currents flow on the outside of the coax cable. The larger the ground losses are, the greater the currents will be. Clip mounts, mag mounts, poor mounting positions, ineffective bonding, and inadequate coax shield returns, all add their toll. Again, a ground strap to the nearest hard point is not a cure!
These issues are covered in more detail below, and in the linked-to articles therein. If you take nothing from this article, it should be this; poor mounting techniques are the single largest contributor to RFI issues, poor antenna efficiency, and continuing problems with RFI, both ingress and egress. As stated below, the use of short, stubby antennas greatly increases this issue.
If your antenna came with a built in reed switch, and your controller doesn't require one, here's some sage advice. Do not DC ground the reed switch leads! Instead, either tuck them back inside the antenna mast, or solder on a wire lug, and connect them to the antenna's mast.
Short, stubby, HF mobile antennas (High Sierra Sidekick®, and Lil Tarheel® particularly) are very popular due to their diminutive size, light weight, and apparent ease of mounting (they're not necessarily less expensive). As a result, owners often resort to trunk lip mounts, luggage rack clamp mounts, and even mag mounts. All of these add to the overall losses, including the (easily kinked) RG174 sized coax most of these mounts utilize. These losses are seldom noticed because owners have nothing to compare them to. If they can make contacts, especially DX ones, that's all they seem to care about.
This said, there is a hidden factor common to all stubby antennas, and it isn't their very-low efficiency. Because of their inherent design, the control leads have an excessive amount of RF flowing on them (common mode currents), which is exacerbated by the poor mounting methods usually employed. This fact requires extraordinary efforts to proper bypass (choke off) the leads, no matter the control methodology. Remember too, a ground strap to the nearest chassis ground point will not negate this RFI issue.
In several of the articles on this web site, I remind readers that it is the mass under the antenna, not along side that counts! This gets misconstrued to mean that a trunk lid is an adequate ground plane. It isn't. Even if you properly bond across the hinges, the level of ground loss is still higher than is would be, if the same antenna were mounted atop the quarter panel. This is especially true if you use a lip mount.
A trunk lip mount is not a very secure mount. Every time you open and close the trunk (hatch), the mount flexes, and it should be evident what the outcome will eventually be. What's more, the fact the start of the ground plane (assuming a trunk lid mount is being used), is below the location where the coax shield connects, ground losses increase. As a result, no matter how many ground straps you use, there will still be common mode currents flowing on the coax. These will have to be choked off, or RFI issues will haunt you ad nauseam.
The photo shows a mix 31, 3/4 inch ID split bead with 6 turns of RG8X. Note that the coax is not tightly wound, but has a diameter of about 3 inches. Any tighter and the center conductor could migrate and cause a short. This choke has an impedance of about 2,500 ohms at 10 MHz.
Coax chokes must be mounted outside the vehicle. If you don't, you'll have both ingress and egress RFI problems. Remember this; common mode current can flow either way. This is to say, out of the coax when you transmit, and into the coax when you're receiving. If this is the case, the majority of the RFI you experience will be as a result of incoming common mode currents. Yet another good reason to properly mount antennas!
Just for the record, short, stubby antennas typically don't require matching, like that described in the next section. This is because of their rather low coil Q ratings, which bring their input impedance close enough to 50 ohms.
The usual call-for-help conversation starts out with these words; "I grounded the antenna." If that were true, it wouldn't work! Obviously, they're referring to the antenna's mount. The second part of their conversation includes; "I grounded the radio." The radio is already grounded through its power cable. These statements point out an unfortunate truth; Far too many amateurs confuse the need for a DC ground with the need for a ground plane. As a result, they often end up creating a ground loop, which they assume is an RFI problem. Here's how to avoid this scenario.
First, if the antenna is properly mounted, no further grounding, strapping, scraping to bare metal, or connections are necessary. To be sure, there needs to be a return for the coax shield, however, that's covered under the words, properly mounted. Bonding is also an important undertaking, but it shouldn't be a work-around for improper mounting. Running ground strap hither and yon to the chassis of the vehicle shouldn't be required, and may actually cause yet another problem.
Here's a good rule of thumb with respect to grounding antenna mounts, and radio chassis'. If a ground strap fixed or reduced an RFI problem, then something else in the installation was amiss.
Everything you need to know to match an HF mobile antenna is in this article, Antenna Matching, and its subsequent article Antenna Coil Adjustment. If you read (or have read) the articles, you'd might know the answer. I say might, because you could have missed the most important part of adjusting a matching coil. To wit: You have to know the exact resonant frequency of the antenna while you're in the process of adjusting the shunt matching coil. You cannot tell the exact resonant point with just an SWR bridge, and that's why you really need an antenna analyzer. Remember! The resonant point is when X=Ø, not the lowest SWR! Additional information on this subject is covered in the Antenna Myths article.
Here are few important points to consider.
It is much preferred to use a home brew shunt matching coil, rather than a commercial one like the MFJ-908 shown here. It should be evident why this is so, once you read the aforementioned articles.
I do not recommend using capacitive matching. Capacitive matching does not DC ground the antenna; an important attribute in minimizing rolling static, lightning protection, and power line safety. When you change bands, you must also change the value of the shunt capacitance.
While UNUN matching does DC ground the antenna, it too requires adjustment between the low bands (160, 80), and the higher bands (40 and up).
All of these alternate matching schemes are a real nuisance if you're using a remotely-controlled antenna and/or an automatic antenna controller.
Whatever matching technique you use, there are a few things you should know. First and foremost, forget the notion that SWR is king! It isn't! For example, a HF mobile antenna with a measured input impedance of 25 ohms, at resonance, will exhibit a 2:1 SWR. However, it is possible to move the resonant frequency and get a lower reading, but the antenna is no longer resonant. When you're trying to adjust the shunt matching coil properly, this fact will get you into trouble. Remember! The resonant frequency is when the reactive element (X), equals zero! It is not the lowest SWR. The only time the two will coincide is when the characteristic impedance of the antenna equals that of the SWR bridge and the coax feeding it.
Assuming you've read the aforementioned articles, and you still can't find a compromise, here are the most common reasons. First, the antenna analyzer should be connected to the antenna through a short piece of coax (≈12 inches), not at the radio end. The shunt matching coil should be mounted as close to the antenna as possible. If you try to use an MFJ-908 for example, and it's mounted near the radio, the chances are very good that you won't find a good compromise, try as you might!
With just one exception (Scorpion®), the motor lead chokes supplied by every antenna manufacturer are inadequate! An inadequate RF choke will effect the input impedance. As I point out in the articles, the motor leads should be disconnected at the antenna when adjusting the shunt matching coil. Once you've matched it, and reconnect the motor leads, the input impedance should not change. If it does, even by one ohm, the choke is inadequate!
High Sierra®, Scorpion®, and Tarheel® (perhaps others) supply a base matching coil with their larger antennas. If you mount these antennas decently, and you use an automatic antenna controller, the chances are you'll have to adjust the supplied coil, usually by elongating it. Because of the mounting location of some factory coils, this is not always possible. The solution is to wind a replacement one as described in the Antenna Matching article which is much easier to adjust. At a minimum, the factory coil should be relocated away from the mounting bracket.
Lastly, antenna manufacturers often tell customers, to cut their coax feed lines to a specific length in order to achieve a good match. All this does is mask the problem by moving the SWR node to another part of the feed line. While this might work in some cases, it won't fool most of the automatic controllers on the market. Caveat emptor.
Poor mounting position is another big problem. If there is a large amount of capacitive coupling between the body of the vehicle and the antenna (especially the coil area), you won't be able to find a matching compromise, no matter what you do. A typical scenario is mounting an antenna on a bumper or trailer hitch mount, on the back of a van or SUV. The antecedent is, if the coupling is large enough, you won't need any matching, as the resistive losses will be high enough to preclude matching. Read this as very low efficiency.
Another is a lack of a good RF return for the coax shield. We're not talking DC ground here, although the two may be coincident. Think of it this way. Wherever the coax shield is connected should be the start of the ground plane for the antenna. When it isn't, losses increase, and matching becomes more problematic.
The photo at left is a Diamond® K400 style clip mount with an NMO look-a-like connector on top. It is very similar to the one with a 3/8x24 stud typically used to support a stubby HF antenna. Note where the coax shield is connected. It isn't at the base of the mount, but about 3 inches away. It is easy to suggest that this fact doesn't matter, but it does as it represents additional ground loss. In fact, you can measure the loss with an antenna analyzer if you know how to do it. The usual work around is to add a ground strap to the base of the mount. Or, to grind off the paint and zinc coating down to bare metal (a very bad idea actually) where the mounting screws contact what ever lip it is attached to. Neither of these techniques work! Keep in mind, attempting to replace an inadequate ground plane with a ground strap, is yet another prescription for poor efficiency, and common mode currents problems.
There is more information on this subject, read the Antenna Mounts article.
Unfortunately, antenna manufacturers don't provide enough lead length, or they have pre-attached connectors. As a result, you have to splice the leads in order to attached the RF choke at the base of the antenna where they must be located. Most owners are reluctant to do so for warranty issues. In some cases, you can remove the antenna's base plug and motor assembly, and replace the factory wiring. However, at least four manufacturers pop-rivet their motor/reed switch assemblies to the inside of the mast making this difficult if not impossible.
Here's what I suggest. Carefully cut the existing wires close to the base of the antenna leaving about 2 inches. Attach a male Molex connector (2 or 4 pin as required) as shown in the photo. When you wind your choke(s), use mating female connectors to extend the leads. This even makes antenna removal easier too.
The electronics industry has standards for just about every facet you can think of. Resistor color codes are a very good example. These standards extend to DC motors too. When the polarity is observed (positive on + and negative on -), the motor rotation will be clockwise with respect to the shaft end. For small DC motors, the positive is always red, and the negative always black. However, not all motors come with leads, or have a specific color which may vary between manufacturers. Antenna motors are no different. In fact, between the 50 or so manufactures of remote controlled, HF mobile antennas, only about 6 or 7 follow the wiring standard. At least 3 use what ever wire they have on hand, thus two otherwise identical antennas may be wired different. So, before you mount your antenna, it's best to check it out on the bench to make sure it gets wired correctly.
While the occurrence of a shorted lead is rare, it occurs often enough to be of concern. When you first unpack your antenna carefully look over the leads where they exit the antenna base structure. Look for any breaks, cuts, or abrasions in the leads. Check for any continuity between each lead and the mast of the antenna; there shouldn't be any! If there is, call your supplier before installation begins.
Not all leads are as well protected with heat shrink or other insulating material like the one in the upper left photo. On many popular brands, the antenna structure where the leads exit is also very sharp. Note the nick in the white wire in the right photo (click for larger view). This nick was caused by the sharp edge at the bottom of the mast (it was pulled further from the base after the short was discovered). Further note, there is no protective sleeve around the leads coming out of the Ameritron SDA-100 shown at right. If you have the wherewithal, add a sleeve as a preventive measure.
After you install your antenna, you should repeat the continuity check. It pays to remember an important point. If any of the leads are shorted to the mast of the antenna, properly RF choked or not, transmitting will destroy what ever controller is attached.
Referring to the photo of the SDA-100 above-right; at the very bottom of the photo are the connections for the coax feed. The supplied shunt coil (not shown) connects across these connections. The hole for the bottom connection (at right) is drilled and threaded clear through the base insulator. Supposedly, this ground connection provides a secure return for the shield of the coax. It doesn't. Since it is very important to provide a secure connection between the coax shield and the ground plane, a short, braided jumper should be installed between the screw and the mounting mast (plate).
The upper screw (barely shown in the photo) is also drilled and threaded clear through the base insulator. If you bottom this screw, you short out the coax via the mounting mast with obvious results. Although the owners manual mentions this, of the four examples I've seen, three had this problem.
These aforementioned problems are not unique to the SDA-100, as several other popular models are nearly identical, or at least have identical problems. That is to say, the connections between the antenna, the shunt matching coil, and the coax feeding them, can become loose. This can cause all sorts of problems, both minor and major.
Another problem area is the connection where the whip screws in. Even when short whips are used, this connections is the one that receives the most stress. If you're experiencing some intermittent receive, this is the first place to look. If you use a quick disconnect for the whip, you should use one that is not spring loaded. One of the best ones come from Breedlove Machine Shop. They also make a combination fold over/QD that's quite clever.
A few additional comments about the SDA-100. For the money, it's a fair performer. Except for the pop rivets holding in motor assembly, it appears well constructed. It does have a couple of drawbacks. The antenna's base plug accepts a one inch pipe thread, which is a better mounting method than the U-bracket its stable mate uses. However, this fact leads some folks to mount the antenna atop a long pipe stub which adds a lot of ground loss, and makes matching difficult. Lastly, as pointed out above, the methodology used to secure the matching coil isn't all that great. If you experience matching and tuning problems, this is the first place to look!
Several antenna manufacturers supply coax with a solid wire center conductor (typically, copper plated steel), rather than a stranded (copper) one. As a result, the center conductor is hard to solder, and breaks easily. The resulting open circuit often results in fried finals.
Some of the aforementioned supplied coax cables are siamesed along with the control (motor) leads. Besides making RF bypassing difficult, it makes the probability of the coax core breaking an absolute certainty.
The type (size) of coax is up to the user, but there isn't a need for anything larger than RG8X, even if you run power. The reason is simply this. The coax runs are short, less than 10 feet in most cases, so the loss difference between even RG58 and RG213 or LM400 is all but moot. What's more, the big stuff is hard to snake through the vehicle. No matter the coax used, you have to be careful not to exceed the bending radius. That's about 5 inches for most RG8 sized coax, and about 3 inches for RG8X.
This article explains how to properly solder PL259s. It also points out the need to use decent quality connectors, and there is good reason to do so. Remember! Poor solderability equates to loose connections!
Belden's RG8X is decent coax, and it weathers well. However, some brands, like Coleman®, aren't worth the effort. If you run high power, and suddenly have an RFI or intermittent SWR problem, the first place to look is at the coax. Click on the photo at left, and look at the small cracks is the foam dielectric. Once the cracks were discovered, the burn spot, right photo, was found by pulling the coax through a soft cloth looking for a bump. Incidentally, the coax in question was in service less than 6 months. The burn occurred in an area protected from the elements, and was not subjected to stress.
It also pays to weatherproof the connections, and Rescue Tape is a good solution. Rescue Tape doesn't hold up to abrasion well, but it sure does seal out moisture. Ace Hardware stores carry Rescue Tape. It also comes in black and clear, besides the colors shown. It is truly amazing material. It's dielectric strength exceeds 8 kV per layer, and it's absolutely waterproof. When you remove it, there is no residue, period!
There are other problems relating to coax. I shudder every time I see an installation where the coax is routed through a door or trunk lid seal. Trust me, this is a problem waiting to happen, especially if the coax is RG174 like that supplied with most trunk lip mounts. And speaking of RG174. The center conductor is #26, and it will barely handle 100 watts at a 1:1 SWR. Dump 200 watts from a Kenwood TS-480Hx, and poof! What's more, at 15 MHz (20 meters) the 6.5 foot length supplied with the K400 mount has almost .5 dB of loss at an SWR of 1:1. At 2 meters it's over 1.2 dB, and on 70 cm, it's almost 6 dB! Or about 3 times greater than RG8X.
The antenna end of the coax feed isn't always a PL259. If yours requires spade lugs, remember this. Crimping alone will not adequately ensure a lasting connection, so soldering is also a necessity. Use either adhesive heat shrink or Rescue Tape to weatherproof the connections. The use of star washers under screws and bolts is also recommended.
Some brands of antennas use a tapered plug at the bottom of the mount which mates with a socket at the base of the antenna. While secure most of the time, the parts are made of brass which corrodes in some climates. NoOx® and other anti-corrosion products will help prevent this.
Every single HF mobile operator has at least one RFI issue, even if they don't realize it. It may be related to on-board electronics, ground loops, or their mounting methodology. What follows are a few causes (certainly not all) most operators don't think about.
Absolutely, the biggest single factor is mounting methodology. I'm not naive, and I know I'll never convince everyone to drill holes in their vehicles, leased or otherwise. Nor will I be able to convince anyone not to use their spouse as an excuse for using a mag mount or other poor mounting choice. This said, be advised: Low mounting (trailer hitch mounts are a very good example), mag mounts, trunk lip mounts, clamps, etc., all reduce efficiency, and increase RFI issues. Ground straps are not a cure, and may actually increase RFI if incorrectly applied.
I mentioned this above, and I'll mention it again. Coax chokes must be mounted outside the vehicle. If you don't, you'll have both ingress and egress RFI problems. To repeat; common mode current can flow either way. This is to say, out of the coax when you transmit, and into the coax when you're receiving. If this is the case, the majority of the RFI you experience will be as a result of incoming common mode currents.
Incorrect wiring practices are the second biggest cause. Aside from the direct RFI issues, the resulting ground loops are the hardest of maladies to find and cure. Do yourself a favor, and take your time to do your installation correctly. Not just to prevent RFI, but from a safety standpoint too!
I already mentioned stubby antennas, but because of their popularity they've become the third biggest cause of RFI issues. They're not cheaper than their bigger brothers, and their efficiency level is about one fourth as good, at best! These facts alone, should be food for thought. Speaking of which; the most popular HF mobile antenna model? The ATAS series from Yaesu. It just so happens, it is also the lossiest, remote controlled antenna money can buy, and it isn't a cheap purchase either!
In fourth place is the lack of understanding of what is, and what isn't, ground! And what is, and what isn't, a ground plane! In about a dozen places on this web site, I remind readers that it is the mass under the antenna that counts, not what's along side. Unfortunately, a lot of amateurs believe a ground strap is a replacement, or a substitute, for an adequate ground plane. It isn't! And just because you DC ground something, doesn't mean it is RF grounded too, or visa versa. Lastly, keep this thought in mind; the higher the ground losses are, the worse the RFI problems will be, no matter how many ground straps you use.
There is one ground strap which isn't needed, but will nonetheless act as a telltale indicator. To wit; If you ground the main chassis of your transceiver, and it cures or lessens and RFI issue, then something else in your installation is amiss. The three biggies, in order, are; RFI flowing on the antenna's control leads, common mode currents flowing on the coax cable, and/or a poor coaxial connection.
If you are using an Icom IC-706 or IC-7000, along with the remote kit, there is one very important point to be made. The 2 mm x 6 mm, phillips head screw which secures the separation cable's main body connection also grounds the shield of the cable. Leave the screw out, and you're going to have RFI issues, some of which you might not even know about. The data is in their manuals on page 10 and 16, respectively.
Scorpion, and a few others incorporate a Polyswitch® or Polyfuse® to limit the maximum current which can be drawn by the motor. This protects the motor from burnout. When the antenna is moved to one end or the other, the typical run current (250 to 350 mils but may be higher). At stall the current more than doubles, and maybe as high as 2 amps (2,000 mils)! In at least one case, stall current exceeds 8 amps! To the uninitiated, this fact can cause a variety of hard-to-solve (and fix) problems.
Automatic antenna controllers often have a park feature, or require the antenna to be parked during the setup procedure. Depending on the make and model, the motor current required to move the antenna to its end of travel may be more than its running current, but less than stall current. As a result, once you move to one end, you can't get it to move in the opposite direction. If your antenna incorporates a Polyswitch®, and this happens to you, just wait a minute for the Polyswitch® to cool, and try again. In rare cases it may become necessary to use a bench supply to unstick the antenna.
Another end of travel problem is hidden in the first paragraph, and you should take heed with the following. Literally dozens of manual controllers, and several of the automatic ones, draw power from the radio's accessory socket. Almost without exception, the maximum current draw from these ports is 1 amp total. What's more, the voltage drop through the radio may exacerbate the end of travel problem, but that's not the worst that can happen.
Most miniaturized radios have an internal fuse. The Icom IC-706 has a 4 amp fuse, and the IC-7000 has a 5 amp one. The ones in the various Yaesu models utilize surface mounted fuses, rather than plug in ones like the Icoms use. In every case, a circuit trace feeds the accessory port(s). This trace will fail long before the fuse opens. The best way to protect your investment, is to use a controller that uses a separate circuit to feed your antenna's motor, or rewire your unit so it does.
Internally, antenna controllers usually use a sub-ohm resistor in series with the motor leads. The voltage drop across this resistor is used to detect the motor run and/or the stall current. At least one commercial controller uses a jumper to adjust the resistance value, rather than change a CPU parameter. As a result, controllers designed this way don't work well with with antennas drawing less than 600 to 700 mils at stall, as they further exacerbate the end of travel stick problem.
Here's a really esoteric problem you won't see often, but one you need to be aware of. Let's assume you're operating on 75 meters, and decide to QSY to 17 meters. At some position of the coil below 20 meter resonance, there will be a dip in the SWR (a harmonic point) which will tell your controller you've reached 17 meters. Most of the time, the SWR will be about the same as the true resonant point. Then let's say you QSY down to 20 meters. If you're using a smart controller like the BetterRF TCSC®, it will correctly sense the correct direction, but in this case it's toward 40 meters, not 20 meters. The direction of travel is easy to change in the BetterRF unit, but with others you'll have to allow the antenna to move to the lowest frequency, stall, and then move back. This is not a fault of the controller, but simply a fact of life. The best way to avoid it is to QSY one band at a time. By the way, this only happens when moving to a higher frequency, not to a lower one.
The input impedance of any HF mobile antenna is partially dependent (largely in some cases) on the ground losses which can vary from location to location. If you set the SWR threshold too low at one location (like your steel re-enforced driveway), your controller might not detect a low enough dip and will continue to run past the lowest SWR point. This can occur even though the controller might incorporate automatic SWR threshold settings. The solution is to set the SWR threshold no lower than 1.5:1, and occasionally slightly higher.
Controllers like the BetterRF unit are the wave of the future, and for all practical purposes, they eliminate the need for any additional metering. Yet a large portion of the amateur community just can't help themselves, and just have to use an external meter. If you do, don't be surprised if the readings differ, especially if your antenna isn't well matched. The reason is simply this. You're measuring the SWR (or power) at different spots along the length of the feed line.
If you're into V/UHF operation, then read the VHF Options article.
Like the other articles on this web site, this one is a living document, and it will continue to grow as required.