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FAQ

f2h1@aol.com




YOU WILL FIND ON THIS PAGE FAQ QUESTIONS AND ANSWERS THAT SOME OF YOU HAVE ASKED OF ME. I AM PUTTING THEM HERE SO THAT YOU MIGHT FIND AN ANSWER TO YOUR QUESTION IF IT IS SIMILAR IN CONTENT.

SOME QUESTIONS CAN BE ANSWERED RIGHT AWAY. WITH MOST QUESTIONS I USUALLY NEED MORE INFORMATION FROM YOU TO TRY AND HELP YOU.

FOR AN EXAMPLE SOMONE WANTED TO KNOW WHAT WAS INVOLVED IN INSTALLING AN AMP IN HIS CAR AND TRUCK AND WHAT HE NEEDED TO GET.

WHAT I NEEDED TO KNOW FROM HIM WAS WHAT KIND OF CAR AND TRUCK, WHAT YEAR, AND WHAT KIND OF RADIOS HE WAS USING ANTENNA'S ECT AND WHAT KIND OF POWER HE WAS LOOKING TO RUN. SO IF I AM GIVEN THE RIGHT INFORMATION I CAN HELP. EACH SITUATION IS DIFFERENT. I HOPE THIS FQA PAGE HELPS YOU. THIS IS PEG LEG STANDING BY :>)


HI PEG LEG I WAS HOPING YOU WOULD PLEASE HELP ME WITH SOME QUESTIONS THAT I HAVE. YOU SEEM TO KNOW MORE AND ARE VERY HELPFUL WHEN IT COMES TO HELPING PEOPLE GET STARTED THEN SOME OF THE OTHERS THAT I HAVE TRIED TO GET HELP WITH SO HEAR GOES.

I WANT TO GET AN AMP FOR MY RADIOS IN MY CAR AND TRUCK 1- IS THERE ANYTHING I NEED TO DO TO MY RADIO BEFORE I HOOK UP THE AMP AND WHY?
2-DOES THE AMP NEED TO BE GROUNDED AS WELL AS THE RADIO?
3-HOW DO I HOOK UP THE AMP?
4-IF THE AMP SAYS ITS A 667 0R A 400 AMP DO YOU ACTUALLY GET A 667 OR A 400 WATT INCREASE IN POWER?
5-IS THERE ANYTHING I NEED TO BUY OR GET TO HOOK IT UP?
6-HOW CAN I PROTECT MY RADIO FROM GETTING FRIED IF SOMETHING HAPPENS TO THE AMP?
HOW CAN I MEASURE THE POWER? OR SEE WHAT I AM PUTTING OUT.
SHOULD I TRUST THE METER ON MY RADIO?
SOMEONE TOLD ME THAT I SHOULD REWIRE THE AMP IS THAT TRUE?
IS THE HOOKUP THE SAME AS IT WOULD BE FOR THE TRUCK OR WOULD IT BE DIFFERENT FOR MY CAR?
DO I NEED TO DO ANYTHING TO MY CAR OR TRUCK TO PREPARE FOR THIS AMP

SHOULD I CHANGE THE BATTERY AND AT WHAT POINT SHOULD THESE CHANGES BE MADE WOULD THE AMP GET INTO THE COMPUTER IN MY CAR OR TRUCK.

I REALIZE THAT THESE ARE A LOT OF QUESTIONS BUT I WAS HOPING YOU WOULD HELP IS THERE ANY THING THAT I LEFT OUT THAT YOU THINK I SHOULD KNOW?

HOOKING UP AN AMP[ Question: OK MY RADIOS ARE COBRA 148 INSTALLED IN MY 1990 FORD RANGER PICK UP I HAVE A 9I HONDA CIVIC WITH MY COBRA 29 LTD AND WANT SOME MORE RANGE OUT OF THIS RADIO

I HAVE'T GOT THE AMPS YET SO I DONT KNOW WHAT I AM GOING TO PUT IN. ANY SUGGESTIONS? I WAS THINKING ABOUT THE 400 FOR THE CAR AND MAYBE THE SAME OR LESS FOR THE TRUCK AND I DONT KNOW WHATS INVOLVED YET IN HOOKING UP THESE AMPS WHAT DO I NEED TO DO OR GET?

Captain, you should be able to run up to a 400 in your pickup, you will need to add an extra Battery identical to the one that is used by your pickup. Do you have a tool box on your pickup? That would be an ideal place to put the extra battery. Wherever you put it, the Two batteries must be wired in parallel with each other using #4 welding cable or larger. The wire from your amp to the battery should be the next size larger than what is coming out of the amp. (never run an amp without a fuse)

The Cobra 148 will run this one just fine, you will need to turn the dead key down so as not to overdrive the amp

The amp should be mounted as far away from the ECM (computer brain) as possible, such as behind the drivers seat, and should be grounded at that point,if your extra battery is in the engine compartment, the power cables should be routed underneath the cab to the engine compartment.

This is where it gets tricky, the radio must be within 3 feet of the amp because you will need a 3 foot coax jumper between the radio and amp, the coax should be RG-mini 8, don't get RG-58U, it has the highest loss factor of any other coax.

The antenna I will leave up to you, the ideal place to mount it is in the center of the cabs roof, if you mount it there, you can't use a long antenna or you will be hitting stoplights and most certainly will not be able to go through the take out line at Burger King. A good antenna would be a Super Penetrator from Palomar, BIC-11 comes to mind or a Super Pentrator made by Dr Crow, is a great antenna. found at most shoot out events. We have a big one here in Daytona Beach every year I have benn trying to find his address or Phone # He is somewhere in Texas, However as of right now I don't have that info

Now, as to the 91 Honda Civic, if your thinking of running a 667v forget it, you can't run anything larger than a 200 watt, why, because the battery in the civic cannot handle anything larger and there is NO room for a second battery.

You would need to run a D-8 battery for the 667) I have a 96 Honda Civic and I run a Palomar 2 pill, I have my amp and Cobra 29 LTD radio mounted in front, on the passenger side of the hump with 18 feet of RG-mini 8 going back to a trunk lid cone mount with a Francis 96 inch antenna, I also have the trunk lid grounded in two places at the hinges.

I have # 10 wire (supplying the radio and amp with power) going through the fire wall near the steering wheel to the battery. I have no ECM problems, however, when I go over a big bridge my lights flicker when I talk, all that means is I have lost my ground and SWR's went up causing the amp to draw lots of current. One other thing, the Cobra has Super Mod with variable control so I don't overdrive the amp. Oh one more thinng I left out dont get cheap on the antenna mount get a real good one specialy made for these antenna's its worth the cost

If I've left out anything let me know, you can even E-mail me, my address is f2h1@aol.com


Hi! I may be the person that MOST RECENTLY signed your guest book and voted for your site (10 BTW). But anyway I'm thrilled to have found someone who actually has a clue, and doesn't just claim to. I live in Birmingham, AL and there is one CB shop 35 miles away.

I am a computer networking guru. I know PC communications on an atomic level. But NOW, I have discovered the JOY of radio communication! (and I'm lost like a fish on land)! I understand wavelength, SWR, watts, ohms law, and basic electronics. I recently became a technician ham (KG4PQR), and now my goal is to become in radio, as I am on a computer.

You will either sell, or see my CB very soon. I have read your "helpful hints" page very carefully. But I am confused about one important thing. What is the difference between 50 ohm and 75 ohm coax? I also install phone systems and cable/Sat hubs for houses.
Because I am a perfectionist, and will not sign off on a job until it shines, I stock Genesis Cable Systems brand RG 6/U Quadshield 75 ohm coax by the 1000 ft box. This stuff is 99% shield. It has braid, then foil, then braid, then foil, then a PVC-like insulator, and 18 AWG solid copper core.
I placed an antenna on my roof using this stuff, and my SWR lands dead on 2.0:1 The SAME length of RG 58u with only 75% shield makes this same antenna SWR out at 1.55, in the same local. What gives? BOTH lines meter out at .1 ohm from end to end.

It would seem to me that the larger cable would be superior, but this is not true with radio, I see. Even though I use different types of wire in my field, even fiber, I have never learned nor heard the meaning of ohm ratings in coax. I know that my RG 6 Quadshield can STOMP the quality of RG 59 in a video app.
So please, in all your expert knowledge, explain to me why it is that I want to rip down my antenna and use it to roast marshmallows! And don't be afraid to use technical words with me, I'll probably get it. I thirst for knowledge, and you have become the only source I trust.
Thank you for your time.
Thank you for your time.
THANK YOU FOR YOUR TIME!
DE KG4PQR
xenonarc@bellsouth

Andrew,
fifty ohm and seventy-five ohm impedance, Humm, impedance is the key word, you can't measure it with an ohm meter.

Next, most radios that "transmit" are made to "Load" into a fifty ohm impedance cable, seventy-five ohm is used for data transmission and low power due to the loading necessary for the device's that use it.

Your experiment using seventy-five ohm proves this, your SWR was 2.0:1 and with the fifty ohm it was 1.55:1. If you want your radio to perform the way it is supposed to, use fifty ohm, also fifty ohm will transfer your RF a lot better than seventy-five ohm.

Hint, if you look up the loss factors on coax cable in the ARRL hand book you will find that RG-58 has the highest loss factor of any of the fifty ohm coaxes, if you want to use the best coax then use RG "Mini" 8, or RG-8, or RG 214 which is double shielded.

you didn't say what antenna and what length coax you used or what brand of meter you used to measure the SWR with.

In some respects you are right about size of coax. The loss factor goes down as the size of coax goes up but you can't go by size alone, the impedance is important also.


My dummy load on my work bench that I use to tune up radios is a fifty ohm / one thousand watt resistor immersed in a mineral oil, now the difference is, the dummy is a pure resistive load. An antenna has Capacitance, and inductance which adds up to impedance.

Beyond what I have said there is the mathematics of transmission lines. I hope I have answered your questions, at least shed some light on things. If you have more questions feel free.
Peg Leg

THINGS EVERY CB'er SHOULD KNOW
THE FOLOWING EDITIORAL WAS NOT WRITTEN BY ME, HOWEVER THE INFORMATION CONTAINED IS INVALUEABLE TO ALL CB'rs AND MAY HAVE A LOT OF ANSWERS TO SOME OF THE QUESTIONS THAT YOU MIGHT HAVE.....


From Firestik® Antenna Co. Technical Support

Every industry has its bottom dwellers. We cannot protect you from them. Consumers who make decisions based strictly on price, or on what someone says instead of what they can do, will often fall prey to the bottom dwellers.

Beware of information from "experts" (real or self-proclaimed). There is antenna theory and there is antenna reality. We have yet to see a vehicle that simulates a lab. While theory is a good starting place...experience is invaluable when it comes to real problems. The knowledge gained from the best book on theory will not necessarily produce the best antenna design.

Some "experts" may "claim" 5/8 wave mobile antennas are not possible because they would need to be 23 feet high. They are wrong! Physical length and ground wave performance are not the same. If you ever hear someone make that claim, ask them how a handheld CB can have a 1/4 wave antenna 8 inches long and mobile 1/4 wave antennas can be anywhere from 12-60 inches long in spite of the fact that a physical 1/4 wave is 108 inches.

Never key up or attempt to operate your CB without a working antenna or "dummy load" (non-radiating antenna simulating device) connected to the radios antenna jack, unless you have extra money to buy another radio, or know a good repairman. All mobile and base transmitting antennas need counter-poise, more commonly called ground plane. The antenna is the reactive unit, the ground plane is the reflective unit. Neither is more important than the other. In mobile installations with standard antenna systems, the vehicle metal (body, frame, etc.) acts as the ground plane. In "no-ground-plane" systems, the coax shield is used for counterpoise.

Most, but not all, manufacturers pre-tune their mobile antennas on a test bench. To protect your radio's circuitry and achieve optimum performance, mobile transmitting antennas (CB, cell phone, amateur, etc.) need to be tuned on the vehicle. Before transmitting, you should check your antenna system for shorts or opens. If you have continuity between the center pin of the connector and the outer threaded housing, you may have a short. Don't transmit! If you do not find continuity between the center pin of the coax and the antenna base, you have an open. Fix it. (See "Testing Continuity") Exceptions: Some base loaded antennas use a center tap design and there will be continuity from ground to center conductor. Also, Firestik "No Ground Plane" antenna kits will have coaxial center pin to ground continuity.

SWR that pegs the needle on all channels almost always indicates a short in your antenna system. Do not attempt to tune the antenna until the short is fixed. Operating with high SWR will probably damage your CB's internal circuits. Make sure that the antenna you are using is the right antenna for your application. Don't use a TV antenna or an AM/FM antenna for your CB. Do not operate your CB without an antenna or dummy load.

Transmitting antennas are sensitive to objects in their "near field of radiation." Tune your antennas in an open area. Never tune inside or next to a building, near or under trees, near or under power lines, and never with a person holding or standing next to the antenna. Try to simulate normal operating conditions.

If you mount two or more antennas close to each other, you will alter the transmission patterns of each one. The affect may be either positive or negative. We recommend that a minimum of 12" exist between your CB antenna and other types of antennas. Your radio cannot tell one component from another. As far as the radio is concerned, the coax, stud mount, mounting bracket, antenna and vehicle is ONE unit. Don't be too quick to fault your antenna until you are sure that all of the other components have been given equal consideration.

Of all antennas returned to Firestik for warranty service, 75% show no signs of being tuned to the vehicle. All antennas should be checked prior to use. Most will require some adjustment. Less than 3% of all returned antennas have actual performance causing problems. Of those, half of the problems are user or installer created. High SWR and other performance problems are 20 times more likely to be caused by bad coax, bad connections, shorted mounts, poor installation location or faulty test meters.

In almost every instance, once you get the same SWR reading on channels 1 and 40, further antenna tuning will not improve the readings. If the SWR is still over 2:1, you have other problems to conquer. Exception: There are rare occasions when the ground plane is so small or large that the system is way out of phase (especially with high-performance antennas). If you have high SWR on all channels and have confirmed that you have no opens or shorts in the feedline, try making a small tuning adjustment in the antenna. There are times when the SWR will drop equally across all channels under unusual ground plane conditions. If you find this to be the case, carefully adjust the antenna. SWR that is high on all channels (over 2:1 but not pegging the needle) after the antenna has been tuned normally indicates a ground plane or coax cable problem.

The doors, mirrors, spare tire racks, luggage racks, etc. on many vehicles are insulated from a good ground with nylon or rubber bushings. This also stands true for fiberglass vehicles. Make sure that your antenna mount is grounded, even if it entails running a ground wire to the vehicle chassis. Bad hard ground at the mount generally equates to less than optimum performance. Exception: No ground plane antenna kits do not require a grounded mount.

If you are hearing whining noises from your radio while your vehicle is running, it is probably due to "dirty power" being supplied to the radio. Under dash power may be more convenient, but the "cleanest" power will be found by running the radio's power leads straight to the battery.

You can never buy coax cable that is too good for your system. Never compromise quality for cost when purchasing coax. Your best bet is to stick with coax that has a stranded center conductor and 90% or higher shielding. Most manufacturers of high performance antennas recommend a specific length of coax cable. If your antenna manufacturer suggests a specific length, give priority to that recommendation.

If your ground plane is good, your mount grounded and, your antenna favorably located, coax length rarely becomes an issue. But, if one or more mismatches occur, you may find high SWR. This can often be corrected by using 18 feet lengths of high quality coax.

Excess coax between your radio and antenna mount should never be wound into a circular coil of less than 12" in diameter. Doing so can cause system problems. Your best option for handling excess coax is to serpentine the cable into a 12 to 18 inch yarn-like skein. Secure the skein in the center with a wire tie and tuck it away.

Single antenna installations require coax with approximately 50 ohm's of resistance (RG-58/U, RG-58 A/U or RG-8X). Dual antenna installations require the use of 72 ohm cable (RG-59/U or RG-59 A/U). Coaxial cables with foam (polyfoam) center conductor insulation should be your last choice for use on mobile (vehicle) installations. Even though it will work initially, it has limited life and does not stand up to the conditions encountered in the mobile environment. Choose coax with polyvinyl insulation when doing mobile installs.

Coax cables should never be cut and spliced together like common electrical wire. Line losses will occur. Coaxial cable with holes in the outer insulation, severe bends, or door, trunk or hood caused pinches will cause performance problems. Treat your coax with care.

If you live in an area where rain and/or sleet is common, wipe your antenna down with a rag that has been coated with WD-40, Armor-All, Pledge, light oil, etc. This trick prevents ice build up that can overload and cause your antenna to break. In an emergency use butter, cooking oil or anything else that will repel water.

When tuning your antenna(s), make sure that you do so with the vehicle doors, hood and trunk closed. If left open, they can cause inaccurate SWR readings. Try to simulate actual operating conditions.

Mobile antennas, for best performance, should have no less than 60% of their overall length above the vehicles roof line. For co-phased antennas to perform optimally, the space between the top 60% of the two antennas needs to be unobstructed. Remember, all transmitting antennas need ground plane (counterpoise). Base antennas, much like "no ground plane" antennas, build it in. Do not use mobile antennas for base station applications unless you know how to build your own ground plane.

If you are installing a single antenna on one side or the other of your vehicle, best on-the-road performance will be realized if the antenna is on the passenger side of the vehicle (Passenger cars and light trucks) Large trucks or vehicles pulling large trailers should put the antenna on the drivers side to avoid the signal from being blocked by the trailer and to keep from hitting road side trees.

Co-phased (dual) antenna installations create a radiation pattern that favors communication directly in front and back of the vehicle. This is why co-phase systems are popular with people who do a lot of highway driving. Co-phase antennas must be center or top loaded. Top loaded antennas are the best. Some people believe that co-phased antennas must be separated by a minimum of nine (9) feet. We have successfully used co-phase antenna systems with spacing as little as four (4) feet. Space alters the pattern and not always negatively. Each vehicle will be different.

Co-phase antennas can improve performance on vehicles that lack good ground plane characteristics (fiberglass motorhomes, trucks, etc.). Instead of using available metal to reflect the radiated energy, the antennas use each others field. When tuning co-phased antennas (dual), it is best to adjust both antennas an equal amount to maintain equality in their individual resonant frequency.

On a co-phase system, if you try to tune each antenna independently using RG-58 type coax and then connect them to the co-phasing harness, you will almost always find that they will appear electrically short as a set. We recommend that you first assemble the entire system. Take all measurements and make all adjustments with both antennas in place.

If you are experiencing SWR that is high across the entire band and have eliminated shorts, opens, groundless mounts and coax as potential problems, suspect lack of ground plane. Try adding a spring or quick disconnect to the antenna base. In some cases, the repositioning of the antenna relevant to available ground plane will solve the problem.

One of the greatest benefits of the FS series (patented tunable tip) antenna is noted when there is lack of available ground plane. If the tuning screw reaches its "maximum out" position before satisfactory SWR is realized, a common 1/4-20 threaded bolt or screw of a longer length can be used to replace the supplied tuning screw. If the vinyl cap is too short to remain in place, the user can disregard it or clip a hole in the top for the longer screw to pass through.

In rare instances, like antennas mounted in the middle of a metal van roof, excess ground plane can cause a problem. This usually shows up as high SWR across the band. In these cases, a tunable tip antenna may not be the best choice. The reason being, the antenna is too long and the tunable tip cannot adjust down far enough (see line 40). If you suspect this, an antenna that wire can be removed from will usually fit the bill (i.e. KW or RP series).

There may be situations when a tunable tip will bottom out before optimum tuning is achieved. If this happens, try removing the knurled jam nut and finger tighten the tuning screw against the o-ring. If still too long, remove the tuning screw altogether. If total removal causes the antenna to go short, cut the tuning screw in half and re-insert it into the tuning extender and re-test. The following items on the FS Series "tunable tip" antennas, when removed, will have an effect on SWR (in order from least effect to most effect). O-ring, jam nut, tuning screw mass (cutting off length), vinyl cap, tuning screw complete.

The vinyl cap on any "tunable tip" Firestik antennas is optional. However, your antenna needs to be tuned as it will be used . . . with or without the tip. Magnetic mounts should be used in temporary situations only. If you leave them in the same spot for a long period, the paint will not age like that of the uncovered areas and/or moisture will be trapped between the mount and vehicle causing rust or discoloration. Periodically lift the magnet and gently clean off the underside of the magnet and the vehicle surface. It is a bad idea to use magnetic mounts and amplifiers together. Magnetic mounts rely on capacitance grounding. This situation can literally cause the paint under the mount to bubble or discolor due to excessive heat build up.

On wire-wound antennas that require wire removal for tuning purposes, best overall performance will be achieved by keeping the loose end of the wire pressed down tightly against the wire coil. If you use power amplification on top loaded antennas and do not process the end of the wire load so it can dissipate its heat into other adjacent coils, you can melt the tip of the antenna.

Generally speaking, center loaded antennas perform better than base loaded antennas, and top loaded antennas perform better than all. For any given antenna design (base, center or top loaded), the taller the antenna the better. With length comes a wider bandwidth (lower SWR over more channels), more power handling capability and overall performance increases. When ultimate mobile performance is desired, function should be given precedence over mounting location convenience and appearance.

Don't confuse SWR with overall performance. You should seek SWR of 2:1 or lower on channel 1 and 40, but keep in mind that best performance may not be found at the lowest SWR readings. For the most part, if you get your SWR below 2:1, on both ends of the band, don't be overly concerned about using meter tricking procedures that bleed off energy.

The SWR meters built into CB radios are okay for general readings, but are rarely sensitive and/or accurate enough for fine tuning of antennas. Use them mostly to indicate serious high SWR problems only. Firestik has tested literally hundreds of SWR meters. A large percentage of these have shown to be off by 0.3 to 0.7 when compared to a piece of certified equipment. There is no standard among production meters. However, unless a unit is defective, most will indicate the most serious problems that you might encounter

Aside from cost, the type of wire used in or on antennas (copper, silver, aluminum, gold, tinned, etc.) has negligible effect on antenna performance. The antenna must be designed to resonate with the wire type and gauge chosen by the designer. However, larger wire gauges will normally increase the bandwidth and heat dissipation abilities of the antenna. Copper is 55% better than aluminum, 27% better than gold and 578% better than tin insofar as conductivity is concerned. Silver will conduct AC/DC current less than 2.5% more efficiently than copper, but the cost to performance is generally unjustified and any gain, insofar as RF transmission is concerned, is negligible.

If devices other than an SWR meter are going to be used between the CB radio and antenna, always tune the antenna system first without that device in line. If SWR is high with the other device in line, you will know where the problem is. In "no ground plane" systems, it is best to choose a system that terminates the coaxial ground at the radio end of the cable. These systems are far less reactive to cable routing errors and will almost always outperform systems that are terminated at the antenna base or antenna end of the coax.

Cables and antennas from standard & no-ground plane kits are not interchangeable. The "No Ground Plane" antennas from Firestik have a yellow band near the base. Wire wound antennas with a plastic outer coating will greatly reduce audible RF static when compared to metal whip antennas. If you leave your antenna on your vehicle permanently, remove the rubber o-ring that is found on the threaded base of some antennas. Tighten permanent antennas with a wrench. Add a lock washer if you want.

If you use mirror mounts and often find yourself in areas with overhead obstructions, tighten the bolts just enough to keep the antenna vertical at highway speeds. If the antenna contacts something overhead, the mount will rotate on the mirror arm and protect your antenna.

If you use long antennas and find that they bend too far back at highway speeds, tilt them forward if possible. When under a wind load, they will end up in a relatively vertical position. On antennas that are topped off with a vinyl tip, make sure that you take your SWR measurements with the tip in place. If you tune your antenna with the tip off and then reinstall the tip, your SWR will change.

Without advocating the use of power amplifiers or unauthorized channels, take note that the Firestik II tunable tip antennas have a fairly large metal tip that broadens the bandwidth and dissipates a considerable amount of heat. If having one antenna for CB/AM/FM is appealing, use a CB antenna and a splitter that allows it to be connected to your AM/FM radio. Devices that let you use your AM/FM antenna for CB use will leave you disappointed.

On a budget? Buy a cheap radio and a good antenna. Aside from added bells and whistles, all CB's are FCC regulated to transmit no more than 4 watts of power. A good antenna on an inexpensive radio will almost always outperform a bad antenna on an expensive radio.

Beware of the wire wound mobile antennas mentioned in ads that claim them to be "full-wave" or "wave and a half". At best, you are being deceived by the misleading association of wire length to actual performance characteristics. Wire length, for all intents and purposes, is irrelevant. With "very" few exceptions, antennas must function as a 1/4 wave or 5/8 wave to be useful on mobile installations. For example, Firestik and Firestik II antennas between 2 foot and 5 foot have a radiation pattern similar to a 5/8 wave reference antenna. However, wire lengths range from 20 feet to 32 feet (0.6 to 0.9 of a full wave length). If wire length was relevant, each antenna would need 22.5 feet of wire.


PERATIONAL 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!


CB RADIOS WITH WEATHERBAND FEATURE

Without getting into a bunch of philosophical rhetoric as to why manufactures like to reinvent their products with seemingly useful add-on's, we would like to discuss the "everybody and me too" marketing of CB radios that have the ability to receive national weather service (NOAA) broadcasts.


First of all, I don't think that receive only weather band features add much value to a CB radio. The extra cost that is added to these radios would be better spent on a mobile scanner. Virtually all scanners have the ability to receive the weather broadcasts and much more. Secondly, the weatherband feature is not all that you might think it would be. You need to be aware of the fact that these broadcasts are made from metropolitan areas … mostly from major airports. The signal is transmitted at a fairly low power level and in an area that usually has a lot of structural interference.

You will start out thinking that the weatherband feature would be useful when you're traveling. However, you will soon learn that when you are away from the city and want a weather update that you will be out of the effective range of the broadcasting center. Then you'll turn on your AM/FM stereo and wait for the news to come on to learn about the local weather. Been there … done that!

If you use your CB in the city there may be some novelty value for the weatherband feature. However, if you have a motorhome or off-road vehicle and use it in the manner for which it was designed, you should be prepared for some disappointment when you leave the comfort of the city.


GENERAL SWR NOTES
1. Setting the SWR.
Insert the antenna whip 1" into chrome antenna adjustment mast at the top of the coil.

Using either the meter built into the radio or a good external SWR meter, calibrate on channel 20. Switch back to SWR and record the readings on three channels; 1, 20, & 40.

If the lowest SWR reading occurs on channel 1, the antenna whip is to long and must be shortened. Loosen the mast set screws and lower the whip 1/4" into the mast. Tighten mast set screw and again read SWR. Repeat until lowest SWR is obtained. If the whip is fully lowered into mast and the SWR is still high, remove the whip from mast. Using a hacksaw, grinder, or bolt cutters, cut 1/4" from the bottom part of the whip. Re-insert the whip into the mast and test again for SWR. Repeat the above procedure until the SWR is below 1.5 of all channels.

If the lowest SWR reading occurs on channel 40, the antenna whip is to short and must be raised. Loosen the mast set screws and raise the whip 1/4", re-tighten set screws and test SWR again. Repeat the above procedure until the SWR is below 1.5 of all channels.
2. The whip is raised to the top, but the SWR is still lower on CH 40.
This generally occurs on vehicles with very small ground plains, such as the compact cars, cars with hatch-backs, etc. It indicates the need for a longer whip than the standard one supplied. Wilson Antenna has a longer whip available for these situations.

3. The SWR on a trunk lid mount is 3.0:1 on all channels. When a reading of 3.0:1 is present on all channels, this indicates a lack of ground for the antenna. For example, some of the vehicles today insulate their trunk lid from the actual chassis or frame, ground of the body. This is done by inserting plastic washers on the trunk hinges, and/or sandwiching a layer of styrofoam type material between the two piece trunk lid. To eliminate this situation, a jumper wire must be installed from the actual bottom lip of the trunk lid to metal on the body of the auto. To accomplish this, loosen one of the hinge bolts on the trunk-lid side and install a braided strap. Re-tighten the bolt. Loosen the bolt on the other side of the hinge (trunk-body side). Install the other end of the braided strap to this bolt and re-tighten. Be sure to leave a long enough loop to prevent pulling apart when the trunk lid is fully open. As added ground insurance, you may wish to add a jumper from the set screw on the trunk lip mount to the hinge bolt on the trunk-lid.

4. If the SWR is good until power is applied:
The antenna is not the problem. In this case, it is the amplifier. You have already established that the antenna is properly tuned and in good working order with low SWR, except when power is applied. Assume a ham operator is on 10 meters using a solid state amplifier. With the radio only, the SWR is 1.1:1; when the amplifier is turned on, the SWR jumps to 2.0:1. The amplifier is not only transmitting at 28 MHz, but is also transmitting on a second frequency of 56MHz. This is known as a "second harmonic" (2X the fundamental frequency of 28 MHz, transmitting at 56 MHz). Thus the SWR meter is reading both the reflected signal of the normal frequency and the rejected second harmonic signal. The antenna will not accept energy transmitted at 56 MHz, and returns it all back to the radio, which shows up on the meter as high SWR because the meter can not tell the difference between 28 MHz and 56 MHz. In fact, as much as 30% of the power is at 56 MHz. This is generally due to an amplifier that is not adequately filtered. Adding a Low-pass filter at the amplifier output is the only solution. For best results, connect the low pass filter directly to the amplifier using a barrel connector.

5. How low can the SWR be brought down to?
Ideally it is nice to get the SWR to 1.1:1, but practically a 1.5:1 works just as well. Some installations will not even allow you to achieve a 1.1:1 SWR because of the grounding of the vehicle, the amount of metal available as a ground plane, and other circumstances. However, the loss with a 1.5:1 (using 18' of coax) is actually less than 1/2 of 1% of your output power, which on a normal 5 watt radio means a loss of .025 watts of power. This means that instead of transmitting 5 watts, you are actually transmitting only 4.975 watts. This is not even noticeable at a receiving station. Therefore, spending the extra time to get below 1.5:1 is purely a matter of choice, especially if you have a high performance antenna.
But, what actually happens if your SWR is 2.0:1 instead of 1.5:1 or less? Most CB radios today have protection circuits that starts to shut down (by lowering the output power) when the SWR reaches above 2.0:1. This reduces the output power of the final transistor amplifiers. So generally, anything between 1.5:1 and 2.0:1 is acceptable and useable for good, solid, reliable communications. Readings of 3.0:1 or higher indicates a problem may exist in the system. Check for complete grounding of the system (see #3 above ).


Hi peg leg, I've seen many different mods for cobra 29 LTD classic PLL 2816c, do any of them work? How about extra channels or even a 10Khz jump? enjoyed your site. Thanks for your reply.
PS I'm on the island of Newfoundland and it's very difficult to get any information here. thanks again, good luck & 73
Sir, OK, here is the story on the 2816c, it can be pin jumped but you will have frequencies that are 5 kHz off, as in 27.430 instead of 27.435.
Therefore in addition to the pin jump you must do a slide mod so you can slide to 27.435.
Wait, it gets (worse), as you go up or down in frequency, the frequency
keeps changing so you constantly have to readjust the delta tune, all of which
necessitates having a frequency counter, and what's worse, this mod makes
the radio very unstable and I do not recommend it!

There is one way to get more channels and that is an expansion kit, you can get one that will allow 40 up and 40 down, there is no way to get the 10 kHz by jumping the pins, even the slide mod will not go 10 kHz.

When people put this mod on the Internet I have to laugh out loud, well, I guess that about sums it up, if you want more channels then get a Galaxy or Superstar, they have it all including frequency counter.

Peg Leg, thanx for the reply and thanx for clearing this up for me. At least you had the courtesy to reply and with the "right stuff"" 73 from the island of newfoundland, tattoo

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