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CB Radio Antennas

In trying to get my CB radio to achieve some sort of reasonable distance, I spent some time on the web doing a bit of research. What you'll find below is some blatantly bootlegged technical information. I probably broke every copyright law in existence in doing so. I'll let you know where to forward my mail and hacksaw. All of the source links precede each article. I have provided the bolding in the text but that was mainly for my own emphasis for what I felt were more important issues for my own installation.

I'm sold on the Firestik antennas. Everyone that I talked to said they're the best. One dealer told me that the truckers all use them because they get "twice the range of other antennas". Specifically, I like their no ground plane (NGP) antennas. A transmitting antenna requires a ground plane off which the signal reflects outward. The best I can describe it, without a ground plane it's like trying to bounce on a trampoline without the fabric center. A motorcycle, being relatively small, either lacks sufficient ground plane or the antenna has trouble establishing one.  I'll let you know how it all turns out.

OPERATIONAL DISTANCE AT CB FREQUENCIES

The popular statement, "There’s good news and bad news ...", could have been written for CB radio. The good news is, sometimes you can talk to someone down the street, or halfway around the world. The bad news is, you may not always be able to talk to someone down the street, or halfway around the world. That is the nature of communications on the CB band.

The frequencies that CB radios operate on are affected by terrain, ambient weather conditions, the forever changing height of the ionosphere, sun spot cycles with their radio frequency (RF) interfering magnetic waves, and the quality and design of the equipment. On any given day (or hour of the day) you might find that the person you spoke with earlier can no longer be contacted. And, while you are trying to talk to that person who is two or three miles away, somebody that lives a thousand miles or more away comes in as if they were in the other room. Since it is humanly impossible to manipulate the things in nature that affect all radio wave transmissions, especially those in the CB band, knowledgeable people with honest intentions will not promise the CB user a specific distance that they can consistently communicate over. Of course, dishonest people are apt to tell you anything when trying to separate you from your hard-earned money.

If ask to make an honest statement regarding the distance that one may expect from a legally operated CB, the statement across the industry must read as follows.

CB operators can expect a fairly consistent operational range of three to five miles in an area of limited obstructions. Prolonged periods of relatively consistent performance between two or more sites in the five to twenty-mile range is a very common occurrence. Consistent operation between locations beyond twenty miles will most often be sporadic. During the course of any given day, for a period that will vary in duration, could occur at any given hour and be in any possible direction, communicating over hundreds, thousands or even tens of thousands of miles with no more than 4 watts is a very probable possibility.There are many things that a CB operator can do to maximize performance under any set of conditions.

  • Adjust the SWR
  • Use high quality coaxial cable
  • Use top loaded antennas
  • Use 5/8 wave antennas
  • Select a longer antenna
  • Mount antenna higher
  • Use antenna(s) with proven history of performance
  • Clean coax and power connections
  • Make sure other station has quality components
  • Use in off-peak periods
  • Use power microphone
  • Have radio peaked by qualified technician
CB is meant to be a fun, useful, inexpensive, and unlicensed means of communications for Joe Citizen. Cost is minimal and airtime is free. If you are aware of the limitations that go along with the frequency, you can expect your CB to perform exactly as it was intended, so long as you do the most that you can do with the pieces you can control. Have fun! Have good conversations! Have CB! Compliments of Firestik® Antenna Company

MOTORCYCLES, ATV'S AND CB ANTENNAS

Do I need a no-ground-plane (NGP) antenna system or will a regular, ground plane (GP) dependent antenna system work better on a motorcycle or ATV? We know that the NGP system will work on any vehicle so long as it isn't mounted in a way that prevents it from radiating energy. But what about a regular GP system? The truth is, we don't know for certain. Read about an ATV installation.

GROUND-PLANE DEPENDENT ANTENNAS

Transmitting antennas, unlike receive only antennas, need some sort of counterpoise in order to function properly. Lack of counterpoise (ground plane) will result in high SWR (standing wave ratio) across the bandwidth (usually at least 2.0:1 or higher). In almost every case, the antenna will appear to be electrically short. If you have a GP antenna mounted and you're are experiencing high SWR you need to be certain that your antenna mount has a good chassis ground. DO NOT test for mount grounding with the coax connected to the radio. Low resistance grounding must be in existence between the mount and the vehicle chassis directly, not through the radio. If the high SWR condition exists after verifying the ground at the mount, chances are there is an insufficient supply of reflective material available for the antenna to use. There is one exception that you may want to look at too. It involves the coax cable.

We cannot stress enough that you use really good coax. Because of vibrations, you should only use coax with a stranded center conductor (RG-58A/U, RG-8X). And, because of the constant exposure to the elements, choose coax with polyvinyl insulation (hard) around the center conductor (versus soft polyfoam). Lastly, you want a very high shielding percentage. We only recommend coaxial cables that have a minimum of 90% shielding. Another anomaly occurs within the coax when the antenna and the available ground plane do not cooperate with one another.

When the antenna and ground plane are compatible the length of the coax cable will have little affect on the performance of the antenna. However, it has been our experience, with our antennas, that incompatibility sets up a condition whereas the cable starts resonating as if it were an antenna. While this defies theory, we cannot tell you how many times that we have corrected SWR problems simply by having the users use an 18-foot (5.5m) coax cable. Again, if you have a good mount ground and still have high SWR we suggest that you give this a try. Before you route the cable, just connect it to the mount and the radio then retest. If the SWR improves, you'll know that the other cable is resonating and needs to be changed. If you find it necessary to use a long cable you will need to deal with a lot of extra cable. Whatever you do, do not coil it up into a nice pretty package because it will probably start acting like a RF choke and re-mess up the installation. Circular coils should be at least 10 inches (25cm) in diameter. We prefer the "bow tie" wrap whereas the coil is brought together in the middle and held there with a twist or cable tie.

Finally, the location of the antenna mount can be of equal importance. Transmitting antennas radiate an energy field along their entire length. The design of the Firestik/FireFly antennas creates stronger energy fields the closer you get to the top of the antenna. Accordingly, it is best to mount the antenna high on the vehicle to eliminate side interference within the antenna's strongest energy field. It is better to use a three-foot antenna on the highest part of the vehicle then it is to use a four-foot antenna mounted one foot lower. Nonetheless, for any given location, longer antennas are usually better than shorter ones.

NO-GROUND-PLANE ANTENNAS
Before any discussion of the NGP system, it is important to understand why NGP systems were even developed. The primary issue is as simplistic as any issue can possibly be. Specifically, the decision to choose an NGP system really gets down to the need or want to have communications on a vehicle that otherwise could not have any. That is, if you cannot make a standard GP system function on the vehicle your choice is to not have communications or go to a NGP system. Insofar as motorcycles and ATV's are concerned, there are two primary issues to consider when using the NGP system. First, the coax cable length (17 feet) CANNOT be altered because it is matched to the antenna. You must find a way to stow it on the vehicle. Secondly, NGP systems cannot be used with a splitter that allows the CB antenna to also be used for AM/FM radio too. Beyond that, they are easy to install and tune.

SUMMARY
We prefer to use ground-plane dependent antennas if there is sufficient reflective material. We try all of the things that we mentioned in this document. If and when we cannot make a GP system work, we go straight to the NGP system. If you can a install the antenna mount to a metal, grounded component of the vehicle there is at least a chance that you could make a normal ground plane dependent system work. But, if you are planning to attach the mount to a fiberglass storage compartment, you had better give a serious look at the NGP kits. We realize that we have a great advantage simply because we have everything at hand. If we are unable to make the GP antenna work we don't have to take it all apart and ship it back someplace. It is easy to take the quick way out and tell everybody to use the NGP system because they really are a no-brainer insofar as achieving satisfactory SWR. In every case, you must thrive for low SWR as it indicates how well the antenna is radiating the energy coming from and going to the citizen band radio. High SWR is an efficiency eater and it can get so bad that your radio can be damaged. Unlike many people, we are not obsessed with SWR to the point that we need it to always be below 1.5:1 but, we sure get uncomfortable when it gets over 2.0:1 (and panic over 3.0:1). Due to the numerous variables, mobile antenna installation is not an exact science. If you do not have the experience or psychological make-up to deal with the potential problems of installing a GP system on a ground plane deficient vehicle, don't get started. At the same time, regardless of whether you install or have someone else install a CB antenna on your motorcycle or ATV, make darn sure that the SWR is below 2.0:1 on no less than the primary channel you talk on, and preferably all of them.

Compliments of Firestik® Antenna Company

Firestik ® No-Ground Plane Side Mount Kit

PURPOSE: The LGX-M2 (where X = antenna length in feet) series, 'No ground plane" (NGP) CB antenna kits were specifically designed to solve the problems associated with the lack of ground plane (counterpoise). This normally occurs on vehicles constructed of plastic, fiberglass, wood or aluminum. This includes, but is not limited to, motorhomes, boats, automobiles and 18-wheeler trucks. Ground plane problems typically show up in the form of high standing wave ratio (SWR) and poor performance. The isolated ground plane that is built into these kits can also eliminate problems on metal base vehicles that lack the sufficient ground plane for proper operation. This could be due to the size of available ground plane (ATV, bicycle, motorcycle, wheelchair, etc.), or because the operator chooses to mount the antenna in a location that is unable too properly take advantage of available ground plane. These kits utilize a stylish mount made specifically for mounting on the vertical side of a vehicle or structure. Aside from being a NGP kit, the main feature of these kits is that they utilize a lightweight antenna. The antennas are at least 40% lighter than the heavy-duty antenna used in the FGX-648 kits. This offers a more stylish look, while at the same time reducing mount stress that is caused by physical weight and wind load.

Component Information

ANTENNA: The antennas used in these kits utilize the same 5/8 wave design as the patented tunable-tip FireFly antennas. The antenna's frequency is altered in order to maintain a desirable center band position when used with the tuned coaxial feedline. Accordingly, these antennas may only be used with the Firestik NGP cable. The core material is a 5/16-inch (0.313" or 8mm) diameter reinforced plastic (fiberglass) tube. Our custom blended formula offers a preferred balance of flexibility and strength. The chrome plated machine brass mounting base has standard 3/8"-24 threads. A high efficiency, voltage increasing helical wind is utilized. Heavy insulated, light-gauge copper wire is used to guard against shorted coils and corrosion induced resistance commonly found on non-Firestik brand antennas. The antenna used in these kits have our patented "no tools required" tunable tip for fast and easy SWR adjustments. The rated wattage for these kits is 100 watts. Each antenna is covered with a static reducing, heavy PVC shrink tubing with both pigment and UV stabilizers mixed in. Available colors are black with yellow tip.

COAXIAL FEEDLINE: The seventeen-foot ((5.2 M) RG-58 A/U coaxial cable used in these kits is of the highest quality. Due to the vibrations found on all mobile installations, a multi-wire stranded center conductor is used to prevent breakage. Surrounding the center conductor is a long life, flexible polyvinyl insulation. To guard against signal leakage, the center conductor is shielded with a copper wire braid that averages about 95% coverage (versus the industry standard of 70%). The coaxial feedline, besides being the conduit for the signal to reach the antenna, serves as a tuned circuit that creates the necessary counterpoise. If a longer cable length is required, the user may add standard RG-58 A/U cable between the radio and system cable, preferably in lengths that are multiples of nine feet.

MOUNT AND HARDWARE: These kits use our molded "teardrop" side mount. The black plastic shell has a textured finish to keep it looking nice. All hardware and coax connections are hidden in the inner wall of the vehicle to maintain visual integrity and prevent weather exposure. For a closer view of the mount, click on the following model number M-2. Because of the increased flexibility of the antenna in these kits, the cost of adding a spring was decided against.

ADDITIONAL FEATURES: Each kit includes a FREE microphone hanger and comes complete with user installation documentation. Warranty: 5 Year: Antenna, 1 Year: Mount & Coax Cable

 Installation Guide for No Ground Plane kits

ATTENTION INSTALLER: We recommend that you read all of this text before starting. Even though we tried to assemble the information in a logical fashion, there may be some considerations that appear in later text that could have helped you earlier. You may even find some helpful information printed under the heading of a mount you do not even have. The NGP antenna kits are extremely user friendly, but we want you to get the absolute most from your system. The time will be well spent.

(T1) CHOOSING A MOUNTING LOCATION

a) All antennas perform best if they are given the room to work. If you sandwich the antenna between two or more objects, or place it in a way that prevents it from being able to radiate its energy in one or more directions, you will have diminished the antennas capabilities. Generally speaking, you should make every possible effort to keep the upper most two-thirds of the antenna above the roofline. If a four-foot antenna causes you to want to install the mount lower, it would be better to use a three-foot antenna and place the mount higher on the vehicle.

b) Transmit antennas are fussy when it comes to their near field of radiation. Objects, especially those made of metal, can distort the radiation pattern and/or cause energy to be reflected back into the antenna. Give your antenna the most freedom that you can and it will perform better.

(T2) INSTALLING THE MOUNT

a) Unlike standard antenna systems, the NGP mount does not require grounding. You may mount it to plastic, wood, fiberglass or any other non-conductive substance. However, if you mount it to a grounded surface, such as a mirror arm, luggage rack, etc., don't worry. The path to ground will be isolated as long as the rest of the mount components are properly installed (refer to pictorial of your specific mount). In every case, the mount MUST remain insulated from the antenna base. If you ever have continuity between the mount and antenna base while the coax is unattached to the radio, you will have a mechanical problem that requires fixing.

b) Roof Mount: The roof mount requires a 1/2" hole and a flat surface, preferably as horizontal as possible. The stainless steel disc and rubber-sealing disk go to the outside of the vehicle. The nylon shoulder washer with the longest shoulder should also be installed on the outside of the vehicle, as should the lock washer, flat washer and spring-stud. Because of the variation in the thickness of material used on vehicles, it is a good idea to make sure that the mount will properly tighten on your vehicle. If one or more of the shoulder washers are preventing the assembly from tightening, you should sand down the shoulder of one or both nylon insulators. Refer to the pictorial of this mount for the proper location of the coax termination. You may use silicone type sealant in conjunction with the rubber gasket for additional water protection if you wish.

c) Molded Plastic Side Mount: This mount is specifically made for mounting on a vertical surface, such as the side of a motorhome, camper, pick-up, etc. Two holes are required, one directly below the other. The top hole needs to be 13/32 to accommodate the shoulder washer while the bottom hole should be drilled to 3/16" diameter. The mount and rubber gasket stay on the outside of the vehicle, the metal plate, shoulder washer, and nuts go on the inside. Refer to the pictorial of this mount for the proper location of the coax termination. You may use silicone type sealant in conjunction with the rubber gasket for additional water protection if you wish. Trick: If mounting on a motorhome with double thick walls, try to select an area where you have clear access from the inside, such as a flat wall or inside a cabinet. Pick up a "no-holes" electrical wall plate at the hardware. Hold it to the wall and make an outline and mark where the two mounting screws go. Now cut out an access hole from the inside that is smaller than the wall plates requirements. Drill your mounting holes from the inside. After everything is finished, mount the wall plate with wood screws fore a professional looking installation.

d) 3-Way Mount: The stainless steel 3-way mount is the most versatile mount on the market. You can mount it in a vertical or horizontal bar (mirror arm, luggage rack, ladder, cargo rack, motorcycle frame, etc.), or use it as a flat mount on any vertical surface. If need be, the angle can be changed by bending the bracket to accommodate minor slopes from vertical. When mounting to a bar, use the supplied clamp and two sets of the stainless steel hardware. If side mounting, we recommend using all four sets of the mounting hardware unless, a) mounting to a strong metal surface, or b) when using the clamp on the inside wall of the installation for added strength. Refer to the pictorial of this mount for the proper location of the coax termination. You may use silicone type sealant in conjunction with the rubber gasket for additional water protection if you wish. Read mounting "trick" regarding double thick walls.

(T3) COAXIAL CONSIDERATIONS
The coaxial cable used on the NGP systems are an integral part of the system. As a matter of fact, neither the antenna nor the coax may be used with other antennas or coax that are not designated a being Firestik NGP components. This is a closed, tuned system.

Unlike standard coaxial cables, if you were to place an ohm meter across the center pin and ground housing of the radio connector, you might think that the cable is shorted. However, on the NGP system, this is normal for we have built a path that allows the coax shield to act as the needed antenna counterpoise. There are some very important issues to keep in mind when dealing with the NGP coaxial cable.

a) Never, ever reduce the length of the cable. It is so sensitive that removing 1/2" could cause the system to be untunable at the desired center frequency of your transceiver.

b) Never, ever ground the coax at the mount. This is unconventional, but necessary. Only the center conductor at the mount end needs termination and connected to the spring-stud assembly.

c) If you need or want a longer feedline, use a barrel connector and add the additional cable between the radio and the NGP cable. We found that lengths that are multiples of nine (9) feet (9, 18, 27, 36, etc.) perform consistently well.

d) Treat the cable gently when routing it through the vehicle. Don't let it become pinched and avoid sharp bends. Protect the outer cover from abrasion because holes in the cover open the door to RF leakage.

(T4) ANTENNA TUNING

Why should you tune your antenna? For maximum performance! When your antenna is tuned in a manner that allows your radio to transmit the maximum amount of power, you will benefit. When you first install your Firestik NGP antenna, set the tuning screw about half way out (the gap between the lock nut and bottom of the tip, the exposed thread area, will be a little more than 1/4"). At this position, assuming that your mount and cable were properly handled, you can safely operate your radio. Nonetheless, we always recommend that you measure the standing wave ratio (SWR) of your system and fine tune it to your vehicle.

Before you start, keep these few things in mind ...

The vinyl antenna cap should be on during all SWR measurements. If you set the antenna with the cap off, then put it on, the SWR will change.- Move the vehicle to an open area when testing. Your readings will be more accurate. Simulate actual use.- Keep doors, hood and truck closed as they can reflect signal and possibly cause false readings.- If SWR on all channels is greater than 2.0:1, you may have a problem with the way the mount was assembled.

Your primary goal should be to have the SWR on all 40 channels below 2.0:1. For best performance across all channels, your specific goal should be to have the SWR on channels 1 and 40 set at the same value. It is really very simple! Even though the meters that are built into some radios are okay for general adjustments, an external meter between the radio and system coax will return the most accurate readings and make your job a bit easier. Radios with built in SWR meters, and external SWR meters always have instructions on how to use the meter. Nonetheless, take a reading on channel 1 and on channel 40 ... write them down.

If the SWR is a "Higher" value on channel 1 than on 40, you need to "Raise" the tuning screw.

If the SWR is a "Lower" value on channel 1 than on 40, you need to "Lower" the tuning screw.

You will develop a feeling for how much the SWR shifts with the amount of change you make in the tuning screw. When you have everything perfect, the SWR on channel 1 and 40 will be below 2.0:1 and will also be close to the same value. If you have accomplished this, the SWR on channel 20 (mid-band) should be below 1.5:1. Remember, low SWR equates to higher output. If you always use a particular channel that is not near the center of the band, you can shift the lowest SWR point to that particular channel. But keep in mind, the further you move from that channel, the higher the SWR will become. For instance, if you "dip" the SWR to its lowest point on channel 5, than move to channels over 25, your SWR may begin to exceed the 2.0:1 value

TUNABLE CB ANTENNAS

Throughout history, manufacturers have found a way to create confusion within their markets. Some do it intentionally to overcome their inability to sell their products or services based upon the merits of the product or service. Other manufactures simply ignore the fact that many users of their products have absolutely no background regarding the product and need the most fundamental information from which to build their knowledge base. The antenna industry, by use of vague terminology, has created some confusion too. Two of these areas, "factory pre-tuned" and "tunable antenna", will be explored.

Factory Pre-Tuned This DOES NOT mean that you can screw the antenna into the mount and go. CB antennas are not plug-and-play devices. "Factory Pre-Tuned" only tells you that the manufacturer has established a standard frequency for the production of their antenna(s) and that the antenna was manufactured to meet that standard. The manufacturers standard refers to a given frequency … NOT a specific SWR reading. Furthermore, the standard is developed on a specific and fixed ground plane. It is doubtful that your vehicle ground plane would match that of the test standard ground plane. You MUST set the SWR of all CB antennas after the antenna is mounted in its final location. Failure to do so will limit the performance of your system and could damage the radio’s circuitry.

Tunable Antenna All CB antennas are tunable in one way or another. Those antennas that have an easy, often mechanical, tuning device are referred to as a "tunable antenna". Accordingly, lots of people think the other antennas are not tunable and so they make no attempt to have the antenna tuned. This is a critical mistake.

Wire-wound antennas without mechanical tuners, that test electrically long, can be tuned by removing wire from the top. If SWR testing indicates the antenna is electrically short, the coils at the top of the antenna can be separated and spaced further apart or accessories that increase the physical length of the antennas (springs, quick disconnects) can be added.

Solid fiberglass antennas (straight or helical wire impregnated in fiberglass resins) that are electrically too long can have the cap removed and the top can be cut off with a hacksaw. If the SWR test on one of these antennas indicates that it is electrically short, the addition of a spring or quick disconnect (or both) is the only way to correct for the short condition. Base loaded antennas with wire whips have a set screw (or two) just below the area that the whip is inserted into the loading coil. By loosening up the set screw(s) you are able to slide the whip up or down as required. Compliments of Firestik® Antenna Company

UNGROUNDED ANTENNA MOUNTS

On standard mobile antenna systems (those NOT designated as no-ground-plane), it is imperative that the antenna mount be grounded to the vehicles chassis. Ungrounded mounts will cause high SWR readings and/or low output power readings.

There are three common situations when the mount may be inadvertently affixed to an ungrounded fixture.

  • Swing-away SUV spare tire racks mounted on nylon bushings.
  • Luggage racks or RV ladders mounted with rubberized bushings.
  • Mirror arms on fiberglass trucks or motorhomes.

For proper performance the mount must be grounded. It should be a standard part of the installation procedure to verify that the mount is grounded. It is an easy test to perform with either a VOM meter set in the Resistance (Ohms) mode or in the audible diode testing mode. Another method of checking is with a self-powered continuity tester. These test need to be made with the coax disconnected from the antenna mount or the radio. If the coax is fully connected and the radio is grounded you will get the false sense that you have a sufficient ground at the mount. Grounding the mount via the coax cable to the radio is not good enough. It requires a direct ground. Either the mount has a good direct chassis ground or it is grounded via the object it is mounted to.

The SWR readings on an ungrounded mount will almost always be 2.0:1 or higher on all channels. You may actually see the SWR dip during the testing procedure (i.e. 3.5:1 on channel 1, 2.5:1 on channel 20, 3.5:1 on channel 40). But, anytime it stays high you can be 90% sure that the mount is ungrounded, there is insufficient ground plane and/or you have low quality or the incorrect coax.

Also, keep this in mind. If it becomes necessary to run a ground wire or braid to a chassis ground point, use a wire of at least 12 gauge. We have reviewed installations where the installer used a small gauge wire (20ga) and when the SWR was tested it fell from over 3:1 to below 1.5:1. However, the power out put was very low due to the undersized path to ground provided by the thin wire. The path to ground must be sufficient enough to carry the power being applied to the antenna.

Compliments of Firestik® Antenna Company

CB Antenna Tuning

This is a document that was copied over from "Wings on the Internet" and forwarded by De Witt Morgan KM6UK.
From: lenwin@freenet.edmonton.ab.ca
Subject: CB antenna tuning

There was quite a bit of discussion a while ago about instructions for tuning CB radios/antennas on the list. I'm not sure that the original request for instructions was answered and I finally found my instructions with some additional information. After a bit of typing, I finally have this in my computer. Hope some of you find it useful. The archives also has some good information.

Instructions for tuning a CB antenna with a Standing Wave Bridge. SWR Measurement copied from original instruction sheet.

  1. Turn the transmitter off. Disconnect the antenna coaxial cable at the transmitter output.
  2. Connect the "TRANSM" connector to transmitter output, and "ANT" to antenna connector. A short cable equipped with male connectors on both ends will be required between the transmitter and the meter. (*Note: adapters will have to be bought or fabricated to tune Honda radio antennas.)
  3. Set the center switch to "FWD" and rotate the adjusting knob to near minimum position (counter-clockwise).
  4. Turn the transmitter on, rotate the adjusting knob for full meter swing.
  5. Next, set the switch to "REF". Read the meter scale. The indication will give the SWR reading directly.
  6. A perfect matching, viz., 1:1 ratio, in ideal from the theoretical point of view. Adjustments on the transmitter and antenna system should be made so that the SWR is as low as possible. An SWR of 1.5:1 is considered satisfactory, taking into account the line losses and slight mismatching. (*note - readings are always taken with the transmit lever -PTT switch- depressed.)

Additional checks and tips. Before tuning:

  • Clean and check all grounds. The ground plate in the trunk of the GL1500 must be cleaned and bolts tightened. A sure way to get a good ground to the m/c main frame is to run a wire from an antenna mounting bolt to the m/c frame under the seat. I have seen several GL1500s with a significant resistance between the trunk framework and the main frame.
  • Check antenna for continuity. Two checks, from the tip of the antenna to the end of the cable center plug, and from the base of the antenna mount to the outside portion of the cable end.
  • Check for infinite resistance between the antenna element and the base. If there is continuity, don't try to transmit. Possible cause may be a crushed antenna cable causing an electrical short.
  • Check cable (coax connections) clean, tight, with no moisture.
  • Vehicle should be outside and at least 5 meters from any buildings or large objects such as trees.
  • SWR meter hooked up to CB end of coax using short connecting cables.
  • Do not touch the antenna while transmitting.
  • Do not let anyone stand close to the antenna. It won't make them sterile but it will screw up your SWR reading.
  • Objective is to obtain an SWR of less than 2 to 1 (2.0:1) on all channels from 01 to 40. If you experience a high SWR on all channels, you are probably experiencing a ground plane deficiency. RE-CHECK your GROUNDS.
  • If the SWR on channel 40 is greater than that on channel 01, the antenna is considered to be 'long' and reduction of physical length is necessary. On m/c antennas with a center loading coil, adjustment is made after loosening the top allan screws. If it is required to cut the antenna, the amount that you cut off should be in increments of no longer than 1/8th of an inch. Remember, cutting is your last resort after all possible trouble areas have been eliminated.
  • If the SWR on channel 01 is greater than that on channel 40, your antenna is considered to be 'short'.
  • Follow the instructions for your SWR. You probably will have to 'recalibrate' the meter each time you make a major change in frequency (channel change) or adjustment in antenna length.
  • Coax for 50 ohm systems employing a single CB antenna should be RG-58A/U. Dual or co-phased systems require a 75 ohm cable, RG-59A/U. Cables supplied with CB antennas should not be cut or shortened as they are a predetermined length. Do not tightly coil excess cable as this will effect your SWR.

Len Winder
'91Gold Wing SE


Here are some of the things everyone, who puts "ANY" antenna, of "ANY MAKE, OR MODEL," on a motorcycle should consider.

Before you even put the antenna on your motorcycle for the first time, take all the little set screws out along the entire length of the antenna, and put them back in with LOCKTITE on them. Save the little allen wrench, you'll need it in the future. I keep one on the motorcycle at all times. Do "NOT" use the type of LOCKTITE that freezes the screws in permanently. Don't use Kraze glue, or anything like it, or, when you do need to get the screws back out to do some repairs, you will strip out the screw heads. LOCKTITE is available in different grades, and will hold the screw from backing out under severe conditions (on a motorcycle,) without using the type that is permanent. A few minutes here, will save you some embarrassing moments, frustration, and money later. If the Comet repair guy, Jim, can not get the screws out, he can not repair them, and therefore must charge you for a new one, at their wholesale price. Do you know of any other company that would even consider doing that?

Last year we were fiber glassing all the Comet Z780 antennas at the middle phasing coil, and later on even at the base. But since then, we have discovered that by tying a piece of 20 lb. test mono filament fishing line just above the center phasing coil, and running it down to the front of the trunk rack on a GW 1500, we no longer have to do all that fiber glass work. It takes all the rearward pressure off the antenna. We only run with the Z780 when we are doing charity events, and/or we are not going to be where we can hit the repeaters easily, or we want to talk bike to bike over long distances. Most of the time around here everyone runs the Comet HP-32, because it is indestructible under most any conditions, and you don't have to take it off when entering, or leaving your garage with it mounted on your trunk rack.

In the Nov. 1996 newsletter was a report on the 4 Comet antennas that we tested last summer while covering 25,000 miles. I will be leaving, I hope, in the next few days on the USA 4 CORNERS RIDE, 10,500 miles, and again will be testing some new Comet antennas. And yes, I will be paying for them, but if they get broken, Comet will repair them free of charge and both they and MARC, will know which antennas to recommend to anyone who is inquiring about what antenna to run on a motorcycle. And I do run them stock until I break them the first time, and then we experiment with what it takes to make them survive on a motorcycle. A newsletter article will detail the new antenna tests.

You see this is a lot work. None of these antennas by "ANY" manufacturer is, or was ever designed to be used on a motorcycle. They are designed to be used on a vehicle that has at least 4 wheels with 4 cushy radial tires on it, not a 2 wheel vehicle with two very hard bias ply tires with rock hard side walls and 40 lbs. of air in them.

Article By: David J. Morrow

August 2001 

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