Properly installing a CB radio Part 1

Cit­i­zen band radio is free and requires no FCC license to oper­ate so it is a good choice for local com­mu­ni­ca­tion. If cell phones fail to work for what­ev­er rea­son, it may be the best method for remote com­mu­ni­ca­tion since its range is bet­ter than FRS and GMRS. When I installed my first CB in a vehi­cle, I was hap­py just to get it in and be able to trans­mit to my bud­dy who lived the next block over. I’ve matured since then and my tol­er­ance for white noise is less than what it used to be. I’ve learned over the years how to prop­er­ly set up a radio sys­tem and I’m nor­mal­ly left with a CB that has few prob­lems. So, I’m writ­ing this to help those of you that use cit­i­zen band radio in your vehi­cles, but may be plagued with noise, weak sig­nals, or are just gen­er­al­ly unhap­py with your radios per­for­mance… at worst, this text should give you a jump­start in your quest for a 1:1 stand­ing wave ratio (and if you have no idea what that is, con­tin­ue read­ing).

Actu­al­ly, the com­po­nents of a radio sys­tem are sim­ple… pow­er, radio, feed­line, and anten­na. If all func­tion prop­er­ly, the radio shouldn’t give you any prob­lems. But for vehi­cle use, with all those wires and work­ing parts, prob­lems do arise. I’ll talk about each of the above men­tioned com­po­nents and oth­er aspects of radio com­mu­ni­ca­tion you may need to know for a prop­er set up. Please keep in mind, these pages are not entire­ly com­pre­hen­sive about CB instal­la­tion or uses and may not answer all your ques­tions… it’s writ­ten based upon my expe­ri­ences in radio com­mu­ni­ca­tion and quite frankly, I haven’t expe­ri­enced it all… yet. But with that being said, here goes…

Anten­na
The two most impor­tant things to con­sid­er when mount­ing an anten­na are ground­ing and posi­tion­ing; when both of these things are con­sid­ered and han­dled prop­er­ly, you should receive a decent SWR read­ing (more on SWR lat­er). The best way to ground an anten­na is to drill holes for the mount­ing brack­et into a met­al por­tion of your vehi­cle. If you’re con­cerned about resale val­ue and don’t want to drill, look into mobile mount­ing units that require no drilling from a sup­pli­er like HRO (Ham Radio Out­let); they sell units for doors, trunks, rain chan­nels, etc.
An anten­na mount­ed in the mid­dle of a met­al roof will get the best sig­nal because it is sur­round­ed by a reflec­tive sur­face. How­ev­er, you may have a prob­lem ground­ing the anten­na with­out caus­ing a leak­ing prob­lem in your roof (but that would of course mean you won’t be asked to dri­ve that often so it has its upside). You should mount the anten­na where you will get the best SWR with­out sac­ri­fic­ing clear­ance or risk­ing dam­age to the anten­na or mount… or get­ting while dri­ving in a rain­storm. I rec­om­mend a pick­up bed imme­di­ate­ly behind the cab, a low­er quar­ter pan­el, or the lid of a trunk. If you mount your anten­na in any of these loca­tions, you should get be able to clear the roof line of your vehi­cle by about 6” to 1’ with a 36” anten­na and trans­mit decent­ly.

Two oth­er things to con­sid­er are anten­na qual­i­ty and length. First, qual­i­ty… sim­ply put, the two best brands of anten­na on the mar­ket are Fire­stick and K40; I would stick with either of these two brands for a mobile unit. Sec­ond, the length of your anten­na is a mat­ter of pref­er­ence quite hon­est­ly, although I will admit that longer anten­nas gen­er­al­ly trans­mit and receive bet­ter. The rea­son it is more a mat­ter of pref­er­ence than per­for­mance is clear­ance. A 6’ anten­na mount­ed on a roof is going to have some clear­ance issues with your garage, trees, etc.; but if you choose to mount your anten­na on a bumper, then a 6’ mod­el would prob­a­bly be fine. I use a three foot anten­na on my pick­up and can trans­mit about 5 miles on the reg­u­lar 40 cit­i­zen band chan­nels. Just anoth­er issue to keep in mind when you pur­chase your set­up.

Feed­line
The feed­line is the length of coax cable from the radio to the anten­na. There are sub­tle dif­fer­ences in coax feed­line based upon insu­la­tion, grade of cable, etc. Gen­er­al­ly speak­ing, the bet­ter the feed­line, the bet­ter it will trans­mit your sig­nal, so buy qual­i­ty coax­i­al cable. When buy­ing the nec­es­sary mount­ing sup­plies, you need to make sure it is all matched for imped­ance… almost all CB radios will have a 50 ohm imped­ance jack for the anten­na input and most coax sold for CB radios is as well- but it doesn’t hurt to ask before you buy.  Much has been said about the length of the feed­line for a CB radio… some peo­ple say that 18’ is the prop­er length, some peo­ple say 17’ is the prop­er length. To be hon­est, imped­ance match is the most impor­tant thing… but I cut my coax to 17’4” stay­ing in prac­tice with radio the­o­ry that the feed­line should be a fac­tor of the wave­length that you will trans­mit on (I won’t bore you with the cal­cu­la­tion with MHz and inch­es). 17’4” is prob­a­bly much more than you will need, but will allow for an anten­na choke if you need it. Be sure to buy feed­line that already has PL259 con­nec­tors already installed if you’re not famil­iar with the instal­la­tion process. But FYI, it’s not dif­fi­cult to learn if you’re famil­iar with sol­der­ing; any radio tech­ni­cian can explain the process.

Radio and Instal­la­tion
First, let me bash on the hand­held units a bit. CB trans­mis­sion is essen­tial­ly line of sight trans­mis­sion and any­thing that blocks the line of sight is going to weak­en the sig­nal. A hand­held CB is for use out­side of a vehi­cle… using it inside a vehi­cle you get min­i­mal trans­mis­sion dis­tance because the sig­nal bounces off the met­al com­po­nents of the rig… and even with a soft top jeep, the sig­nal still needs to pass through a bar­ri­er and as a result it’s weak­ened. So if you’re using a hand­held and won­der why you can’t hear much, there’s the rea­son. I will admit that I have a portable unit, a Mid­land 75–820, that is a hand­held unit with a sep­a­rate mag­net­ic base anten­na for use while in a vehi­cle. It’s per­for­mance is ade­quate but not opti­mal.

Frankly, the mid­land set­up has two major prob­lems, 1) engine noise which can be caused by the rota­tion of the alter­na­tor feed­ing back through the elec­tri­cal sys­tem (a prob­lem more preva­lent on old­er vehi­cles but still present on many today) because the ground for every­thing is through the cig­a­rette lighter… and 2) the lim­it­ed vol­ume the unit puts out with such a small speak­er (an oper­a­tor in a loud truck or top­less jeep may have prob­lems using this CB when dri­ving on the high­way). I use this unit only as a back­up unit or in a sec­ond vehi­cle that doesn’t have a hard wired set­up.
I cur­rent­ly use a Cobra 18WXST II. It is a rea­son­ably priced unit from a qual­i­ty man­u­fac­tur­er. Regard­less of what you buy, most qual­i­ty units will have an inter­nal noise fil­ter, scan­ning fea­ture, and NOAA weath­er bands, but be sure to buy the unit best suit­ed for your needs. If you’re inter­est­ed in SSB trans­mit­ting or extend­ed range, you may want to get a bet­ter unit; I rec­om­mend the Cobra 148GTL.

Now, it sounds as though it should be com­mon sense but be sure to mount the unit where it will be easy to use and not an obstruc­tion while using the vehi­cle (the dash board is prob­a­bly a bad choice as is the foot well near the ped­als). I rec­om­mend bolt­ing the unit to the cen­ter con­sole or using a RAM mount some­where on the trans­mis­sion hump.  Clean­li­ness of instal­la­tion should be con­sid­ered too. Do you want coax cable on the floor of your back seat or run under the car­pet? Do you want to run the wires out an exist­ing hole in the chas­sis or drill a new one? I nor­mal­ly run the pow­er line through the dash and direct­ly to the bat­tery; this elim­i­nates some noise you can receive when tap­ping into an exist­ing hot line or fuse (more on that in part 2). Be sure to use a fuse for your radio before hook­ing it up or you may soon be buy­ing a new radio. The coax­i­al cable I nor­mal­ly run under the car­pet or floor mats to the rear of the cab­in and drill a small hole (if nec­es­sary) near the mount.

This equip­ment and these instal­la­tion tech­niques should help you set up a radio prop­er­ly. The cost shouldn’t be too bad… all of this can be obtained for under $100 with new equip­ment but if your bud­get allows, feel free to spend more. In part two of this arti­cle I will cov­er some com­mon CB radio prob­lems and how to fix them.