[ARCHIVED THREAD] - Setting up a CB Radio (Page 1 of 2)
Posted: 2/12/2009 3:48:31 PM EDT
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I have a Cobra 19 XS, with origional antenna/wiring. It was my Dad's from like 20 yrs ago. How to I "set it up"? I have seen SWR meters being mentioned on different sites, do I really need one of these? Thanks, Mike |
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You key that radio without checking the SWR of the antenna, and the radio may pop it's finals instantly, or it may pop them in a week...
Get an SWR meter, stick it inline between the antenna and the radio, and adjust the antenna till you reach an SWR ratio nearest you can to 1:1 Lots of guides online such as: http://www.stu-offroad.com/cb/cb_install-2.htm |
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where in MI are you?
often times a truck stop will have a CB shop, guys there can help you out either by "tweaking" your CB, checking your SWR or just advice about your setup. my CB saved me from a bad accident outside grand rapids, MI a few years back. definitely worth it! |
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Quoted:
What are you putting it in? Nevermind,you have a Cobra 19,I doubt anyone's gonna steal that.....however,if you decide to upgrade to a -29,go to a Pilot truckstop,they have a nice CB box,that comes with a speaker/all the wiring,so you can take it out. It ain't cheap,about $139,but it really looks good,I got a free -29,thanks to my PilotPoints,and that's what I'm gonna get for the Wrangler. |
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I bought a Cobra 29 NW brand new off Egay for $99. Took it to my local radio shop to get her peaked and tuned. The dude told me I'm getting around 40 watts our of her.
On a good night i can probably talk 20 miles away maybe more. If your running the factory 4 watts you wont be get out for shit. |
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Quoted: What are you putting it in? A 2000 Ford Focus. Hey, would this be a good SWR Meter to set up my CB? I saw it at my local radio shack today and I'm thinking about getting tomorrow (same price as online). Thanks for all the responses guys. I am a total noob when it comes to CB's. I've been using them at a winter job (handheld ones) and decided that they are so much fun that I had to put one in my car. Just so happens that my Dad had one that I could use  BTW, any ideas on mounting this CB unit in the cabin of my Focus? The only two ways I can think of that are practical are: 1) Mounting on the headliner/roof (how would I go about attching this?) or 2) Mounting under the center armrest above the parking brake handle (my parking brake doesn't work anymore so it doesn't matter that the CB would be blocking it). Any other ideas? |
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ground your radio, ground your antenna
run power direct off the battery (if you can) proper fuse in-line RG-58 or RG-8x should work fine for mobile applications (heck, for home too, provided you're not running it a long way) solder all your connections keep splices to a minimum (max one per wire IF you must) (power and non-coax) do not splice coax if you can help it, connectors cause problems so keep them to a minimum don't skimp on cable size and keep lengths to a minimum. if you can't get a decent swr (I'd be surprised) you may have to adjust the length of your feedline (coax) (taking that everything else is correct) solicit the help of a ham if you know one, they should be able to help you. *YMMV here as they tend to just give the license away now, so the older hams would be a better bet (as well as them having an SWR meter) 
ETA: seen your question... that SWR meter will suffice. better to get some help from someone that comes with an swr meter
(save yourself some money) I don't think there are too many options for mounting in your car. got pics? it's hard to visualize w/o knowing what it looks like on the inside. |
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Quoted:
Or you can do it the easy way,just talk to truckers. The reply will most likely be like this......."yeah,you're gettin' out,just like my ex-wife,all over town!!!!"Quoted:
What are you putting it in? A 2000 Ford Focus. Hey, would this be a good SWR Meter to set up my CB? I saw it at my local radio shack today and I'm thinking about getting tomorrow (same price as online). Thanks for all the responses guys. I am a total noob when it comes to CB's. I've been using them at a winter job (handheld ones) and decided that they are so much fun that I had to put one in my car. Just so happens that my Dad had one that I could use
BTW, any ideas on mounting this CB unit in the cabin of my Focus? The only two ways I can think of that are practical are: 1) Mounting on the headliner/roof (how would I go about attching this?) or 2) Mounting under the center armrest above the parking brake handle (my parking brake doesn't work anymore so it doesn't matter that the CB would be blocking it). Any other ideas? 
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Quoted: ground your radio, ground your antenna run power direct off the battery (if you can) proper fuse in-line RG-58 or RG-8x should work fine for mobile applications (heck, for home too, provided you're not running it a long way) solder all your connections keep splices to a minimum (max one per wire IF you must) (power and non-coax) do not splice coax if you can help it, connectors cause problems so keep them to a minimum don't skimp on cable size and keep lengths to a minimum. if you can't get a decent swr (I'd be surprised) you may have to adjust the length of your feedline (coax) (taking that everything else is correct) solicit the help of a ham if you know one, they should be able to help you. *YMMV here as they tend to just give the license away now, so the older hams would be a better bet (as well as them having an SWR meter) ETA: seen your question... that SWR meter will suffice. better to get some help from someone that comes with an swr meter (save yourself some money) I don't think there are too many options for mounting in your car. got pics? it's hard to visualize w/o knowing what it looks like on the inside. Small technical correction, but changing the coax length doesn't affect the SWR. It may affect what's indicated (under certain circumstances), but it doesn't actually alter the SWR. And to the OP: If you're not too far away, I have an SWR meter you can use. |
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Quoted: Quoted: ground your radio, ground your antenna run power direct off the battery (if you can) proper fuse in-line RG-58 or RG-8x should work fine for mobile applications (heck, for home too, provided you're not running it a long way) solder all your connections keep splices to a minimum (max one per wire IF you must) (power and non-coax) do not splice coax if you can help it, connectors cause problems so keep them to a minimum don't skimp on cable size and keep lengths to a minimum. if you can't get a decent swr (I'd be surprised) you may have to adjust the length of your feedline (coax) (taking that everything else is correct) solicit the help of a ham if you know one, they should be able to help you. *YMMV here as they tend to just give the license away now, so the older hams would be a better bet (as well as them having an SWR meter) ETA: seen your question... that SWR meter will suffice. better to get some help from someone that comes with an swr meter (save yourself some money) I don't think there are too many options for mounting in your car. got pics? it's hard to visualize w/o knowing what it looks like on the inside. Small technical correction, but changing the coax length doesn't affect the SWR. It may affect what's indicated (under certain circumstances), but it doesn't actually alter the SWR. And to the OP: If you're not too far away, I have an SWR meter you can use. I'm in-between Lansing and Detroit, along I-96. Actually, I don't think this CB buzz thing will stop at my current setup, so I might as well get a SWR meter  I'm going to try to get my buddies to get setups too, then we can have fun on trips with lots of friends. As for pictures, I will take some today of the antenna, CB unit and my passenger compartment to give you an idea of what kind of situation I'm in. Thanks |
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Ok, so I'm having issues tuning the SWR on my CB. It appears that no matter which direction I adjust the antenna, all of the SWR readings are above 3.0 for channel 1 and 40. I will be listening to all of the channels so I figured I would adjust the SWR to be good for all of the channels by making sure channels 1 and 40 were close in acceptable SWR readings. I am wondering if its the antenna, b/c its really old? Well I've included some pics (with captions) below for you to evaluate my setup/ issues. The vehicle I'm mounting the CB in:  The old antenna I'm trying to adjust (is it a problem to wrap the cord around the roof rack bar like I did in the pic?):  The SWR meter I'm using:  The CB I'm using:  The plug-in end of antenna:  #1 place where I'm thinking of mounting the CB:  #2 place where I'm thinking of mounting the CB:  |
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Candy Cane? Hey anybody know a Candy Cane?
this might not end well. 
Joy Ride |
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Not good to coil your coax.
Mounted under the arm rest you won't be able to see what channel you'r on or see the power meter. ARFCOM has a radio forum where you'll get a lot better signal to noise ratio than in general discussion. http://www.ak47.net/forums/forum.html?b=10&f=22 |
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Quoted:
Buy 102" SS whip and mount. Install mount. Buy new coax with ends and hook to antenna. Hook radio to power and coax and you are good to go. Thats it. 102" whip, or (if you dont want your focus to look like a remote controlled car with a 9 foot antenna on it) a wilson 1000. coax and your CB. Quoted:
You key that radio without checking the SWR of the antenna, and the radio may pop it's finals instantly, or it may pop them in a week... Get an SWR meter, stick it inline between the antenna and the radio, and adjust the antenna till you reach an SWR ratio nearest you can to 1:1 SWR, quality coax, etc dont really matter when youre running a low end rig. a $300-$600 radio with a decent amp you need to set up properly. a cobra 19 not so much |
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With the SWR being high across all channels, I would suspect a bad antenna/coax. The antenna you show is not a very good one to began with, so I will suggest a Wilson 1000 mag mount if you want to use a magnet on the roof, or a trunk mount. Wilson's are great antennas. I currently have a Wilson 5000 mounted on the roof (drilled through)
You MUST check/set the SWR no matter what type or brand of antenna, or risk damage to the radio, and reduced performance/range of the signal. The SWR meter you show is a good one, I too, have one of them. Select a place to mount the radio where you can see it, maybe between the seat and console facing up, if it's a temporary type install or just use your imagination. I am a full time CB user/hobbiest with Cobra 2000 base stations, IMAX antenna, mobiles in all the vehicles, and if I'm in the truck, my radio is on. I have alot more equipment...this is just some of it. There is plenty of talking going on, and when on the road channel 19 is pretty darn entertaining, just beware of the language in the bigger cities and within 5 miles or so, of a truckstop, as it can get pretty foul. I will say, during an incident such as weather related emergencies and such, the drivers on 19 have a wealth of info, if you take the time to listen to them talk to each other, on routes, fuel, and road conditions. Unlike some...who will try to sway you in one direction or the other, or who will say that there is nothing to be heard on CB Radio, I will say give it a try, it is pretty fun, and MAY lead you to HAM...we all have to start somewhere. I like to think of myself as a radio operator. All in all, i enjoy using CB Radio on the road, and to talk to friends around my home location. Feel free to contact me with any CB Radio questions, and I will try to help you out. |
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Quoted: Not good to coil your coax. Mounted under the arm rest you won't be able to see what channel you'r on or see the power meter. ARFCOM has a radio forum where you'll get a lot better signal to noise ratio than in general discussion. http://www.ak47.net/forums/forum.html?b=10&f=22 Thanks for the info. The armrest actually flips upward, so I was planning on mounting the CB to the underside of the armrest to it can flip up w/the armrest and I can see the pannel/dials. |
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Quoted: It would be better to have a good antenna mounted through a hole in the roof. A decent second option would be a body seam mount. Mag mounts are not great. No ground at the base of the antenna, and if you get into a fender bender they become a projectile. Well, I was thinking about a trunk mount or affixing a mirror mount to my roof rack bar. I was told that you want to mount it as high up on the vehicle as possible, such at the roof. The issue is that I can't really get an antenna that is higher off the ground than the one I have now for the CB, because when I go to school the parking garages are pretty low and the gate sometimes hits my factory antenna for the existing stereo  Is there a trunk mount that doesn't attach itself to the trunk lid but instead to the side of the opening in the trunk? When my trunk opens it actually rotates really far in so that the trunk lid is almost touching the bottom of the rear glass. |
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Is there a trunk mount that doesn't attach itself to the trunk lid but instead to the side of the opening in the trunk? When my trunk opens it actually rotates really far in so that the trunk lid is almost touching the bottom of the rear glass.
The trunk mount type of antenna can mount anywhere on the trunk lid, so long as it is relatively the same size all the way around. Mag mounts are good for quick removal if you don't mind doing it. You are correct...the higher, the better, for a mounting location, and to take it a step further, more towards the center of mass, for a better radiated signal pattern. But the trunk will work just fine, probably perfect for you, as far as parking garages and gates are concerned. The antenna stinger can bend when going through, or into these area's without hurting it. I have a Wilson 5000 on the roof of a lifted F-350, and use the drive through's all the time. The stinger just bends over, then pops right back up, 4 years, no damage, and 1.2:1 SWR on the Palstar meter that is always inline and on. |
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Quoted: Is there a trunk mount that doesn't attach itself to the trunk lid but instead to the side of the opening in the trunk? When my trunk opens it actually rotates really far in so that the trunk lid is almost touching the bottom of the rear glass. The trunk mount type of antenna can mount anywhere on the trunk lid, so long as it is relatively the same size all the way around. Mag mounts are good for quick removal if you don't mind doing it. You are correct...the higher, the better, for a mounting location, and to take it a step further, more towards the center of mass, for a better radiated signal pattern. But the trunk will work just fine, probably perfect for you, as far as parking garages and gates are concerned. The antenna stinger can bend when going through, or into these area's without hurting it. I have a Wilson 5000 on the roof of a lifted F-350, and use the drive through's all the time. The stinger just bends over, then pops right back up, 4 years, no damage, and 1.2:1 SWR on the Palstar meter that is always inline and on. Thanks, I was able to get the magnet mount to work that I have now. I tuned channels 1 and 40 to have a SWR of around 1:2 (according to the meter), and channel 20 and others in the middle don't move the needle past 1. So, if you SWR is good does that mean that your mic is transmitting correctly? Also, does it mean that you will achieve the best reception? Thanks to all of you for your answers, I would have had a hell of a time trying to figure this out myself  |
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Quoted:
Quoted:
Buy 102" SS whip and mount. Install mount. Buy new coax with ends and hook to antenna. Hook radio to power and coax and you are good to go. Thats it. 102" whip, or (if you dont want your focus to look like a remote controlled car with a 9 foot antenna on it) a wilson 1000. coax and your CB. Quoted:
You key that radio without checking the SWR of the antenna, and the radio may pop it's finals instantly, or it may pop them in a week... Get an SWR meter, stick it inline between the antenna and the radio, and adjust the antenna till you reach an SWR ratio nearest you can to 1:1 SWR, quality coax, etc dont really matter when youre running a low end rig. a $300-$600 radio with a decent amp you need to set up properly. a cobra 19 not so much Really? So keying into a dead short is just fine then. I'll keep that in mind. 
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So, if you SWR is good does that mean that your mic is transmitting correctly? Also, does it mean that you will achieve the best reception? A low SWR will improve your antenna's efficiency. In other words, bad SWR means your signal may not reach beyond your driveway, and a real bad SWR indicates a problem, such as faulty antenna or coax... which left unaddressed can/will likely lead to catastrophic failure. Antenna tuning isn't a myth... and an SWR meter does more than just aid in tuning, it alerts you to major issues before you're wondering why your radio let out smoke. |
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Is there a trunk mount that doesn't attach itself to the trunk lid but instead to the side of the opening in the trunk? When my trunk opens it actually rotates really far in so that the trunk lid is almost touching the bottom of the rear glass. Yes, it is a body seam mount. Essentially, it is a stiff "L" bracket that attaches to the body rather than the trunk mount. I have on on my Neon for my Comet SSB-5 vhf/uhf antenna. Any ham shop should have such a thing...or look online. I couldn't rapidly find one at a ham store to post here, but if you search ebay for "NMO L bracket" you will see many. If I can stop hacking and sneezing long enough to go outside, I'll take and post some pics for you. |
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Quoted: Quoted: Is there a trunk mount that doesn't attach itself to the trunk lid but instead to the side of the opening in the trunk? When my trunk opens it actually rotates really far in so that the trunk lid is almost touching the bottom of the rear glass. Yes, it is a body seam mount. Essentially, it is a stiff "L" bracket that attaches to the body rather than the trunk mount. I have on on my Neon for my Comet SSB-5 vhf/uhf antenna. Any ham shop should have such a thing...or look online. I couldn't rapidly find one at a ham store to post here, but if you search ebay for "NMO L bracket" you will see many. If I can stop hacking and sneezing long enough to go outside, I'll take and post some pics for you. Well, I found one on ebay, and I don't really want something that will drill into the body of the car. Is there any way for it to attach some other way? Also, do SWR readings get affected if the car is running or not? I routed some of the coax cable under the dash/steering wheel near the inside fusebox and I only tested it with the car not running. |
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Is there a trunk mount that doesn't attach itself to the trunk lid but instead to the side of the opening in the trunk? When my trunk opens it actually rotates really far in so that the trunk lid is almost touching the bottom of the rear glass. Yes, it is a body seam mount. Essentially, it is a stiff "L" bracket that attaches to the body rather than the trunk mount. I have on on my Neon for my Comet SSB-5 vhf/uhf antenna. Any ham shop should have such a thing...or look online. I couldn't rapidly find one at a ham store to post here, but if you search ebay for "NMO L bracket" you will see many. If I can stop hacking and sneezing long enough to go outside, I'll take and post some pics for you. Well, I found one on ebay, and I don't really want something that will drill into the body of the car. Is there any way for it to attach some other way? Also, do SWR readings get affected if the car is running or not? I routed some of the coax cable under the dash/steering wheel near the inside fusebox and I only tested it with the car not running. Shouldn't make a difference, or interfere with the standing wave ratio, no. You are kinda fucking around with this antenna deal though. Getting some stick on glass or clip over the window type deal is fail. Your best bet, if you don't want to drill... get a good magnet mount, like the Wilson 1000, and remove it when you enter parking ramps or w/e. |
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Well, I found one on ebay, and I don't really want something that will drill into the body of the car. Is there any way for it to attach some other way? Also, do SWR readings get affected if the car is running or not? I routed some of the coax cable under the dash/steering wheel near the inside fusebox and I only tested it with the car not running. The short answer is, drill the car. It doesn't reduce value, and when done right it has zero long term effect. I suppose it is not impossible that you might have an OEM fastener somewhere near the body seam, and you could custom make a mount that uses that fastener. It probably will not work well, as the fastener is virtually guaranteed to be fairly far from the seam. My Comet antenna on an L-bracket has been on my Neon for over five years. I installed it with silicone sealer and stainless screws. No leaks, no rust, no damage, and it has never loosened. K0BG has a lot of good information on mobile installations, including pictures. |
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Quoted: Also, do SWR readings get affected if the car is running or not? I routed some of the coax cable under the dash/steering wheel near the inside fusebox and I only tested it with the car not running. Standing Wave Ratio is a measure of reflected transmitter power, expressed as a ratio. It indicates how well the antenna is matched to the transceiver. If you are testing the SWR on channel 1, what you are actually doing is seeing how well the antenna resonates at 26.965MHz. If the antenna is able to perfectly resonate at that frequency, the SWR will be indicated as 1:1. That is to say, it indicates 4W of forward power, and 0W of reflected power. A slightly more accurate way to phrase it, is "The driving force (transmitter) impedance is equal to the load (antenna) impedance." Since all CB radios have a fixed transmitter output impedance of 50 ohms, and the coaxial cable you're using has a characteristic impedance of 50 ohms, the only variable in the equation is the antenna. An antenna that is capable of absorbing (and therefore radiating) 100% of the RF energy applied to it, will present a load impedance equal to that of the transmitter. So 50/50 =1, thus SWR is 1:1. If you measure the SWR to be 1.3:1, what this really means is that there is a mismatch between the transmitter and antenna impedance. We know your transmitter and coax impedance are 50 ohms, so this must mean your antenna impedance is approximately 38 ohms. 50/38 = 1.3, so SWR is 1.3:1. This means that not all of your forward power is being absorbed (and therefore radiated) by the antenna, and some of that power is being reflected back. But how much? The ratio of voltage (or current) reaching the antenna, to that reflected back down the coax from the antenna, is called the "coefficent of reflection", or "k". This is calculated by: k = (SWR -1) / (SWR + 1) So, using your situation where SWR was measured at 1.3, we plug the values in: k = (1.3 - 1) / (1.3 + 1) k = 0.17 Power (wattage) is proportional to impedance or voltage squared (I2 or V2). So then, reflected power is k2. Thus, your reflected power is .172, or .0289W. What does this mean? It mans that 3.9711W are being radiated by the antenna, and .0289W are being reflected back. Put another way, A full 98% of your transmitter power is being radiated by the antenna. In other words, you're fine. At HF frequencies, anything under 2:1 is fine (do the math, using the formulas above). Why do I say "at HF frequencies"? Because at these lower frequencies, there isn't much signal loss through coax. To keep the math easy, I didn't account for feedline losses above. You're not really radiating 3.9711W at the antenna, because you lost some power through the coax. Just not much. In fact, it's negligible unless you have like 100' of coax in the car, or something. Also note that db losses per foot increase with SWR (specifications for signal loss in coax assume a 1:1 SWR). At VHF and UHF frequencies, the losses are much greater for each foot of coax. Thus at these frequencies, keeping the SWR as low as possible is very important. Now you know for yourself, that the short answer to your question is "No. It doesn't matter if the car is running or not". Now that you know what SWR is and what it actually means, you can impress your CB buddies with your newfound knowledge. If you encounter people in your CB travels that insist coax length affects actual SWR (not indicated SWR), return here for another tutorial, so you too can lay the smackdown. Enjoy. It's a fun hobby. |
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I will have to add that the antenna you show is a piece of crap. No offense intended, but the antenna is 90% of the system. It is often said a POS radio with a good antenna is better than a great radio, and a POS antenna.
Ditch the el-cheapo antenna, spring for a Wilson 1000 OR a K-40 (your choice of mount) set the SWR correctly, and you will TX and RX 10 times better than with the antenna you are currently working with. Once you have the setup working properly, get the radio aligned, peaked and tuned, and you will be good to go. |
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Quoted: I will have to add that the antenna you show is a piece of crap. No offense intended, but the antenna is 90% of the system. It is often said a POS radio with a good antenna is better than a great radio, and a POS antenna. Ditch the el-cheapo antenna, spring for a Wilson 1000 OR a K-40 (your choice of mount) set the SWR correctly, and you will TX and RX 10 times better than with the antenna you are currently working with. Once you have the setup working properly, get the radio aligned, peaked and tuned, and you will be good to go. How do I adjust the setup to "work properly"? Does that mean setting the SWR at its lowest for channels 1 and 40? Also, when you say "aligned, peaked and tuned" what do you mean by this? Thanks to all of you again, you have been immensely helpful on this. What started as a free way for me to put a CB in my car may have turned into another expensive hobby  (ya know, you people are good at doing that )
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