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CB (cobra 19) / SWR ???

4376 Views 14 Replies 6 Participants Last post by  Alec
hey all...

so i just got a Cobra 19 DX IV with a 4' Firestik 2 antenna. so i went to the CB shop to get a CB Speaker & PA Horn.. so when i was there i asked the guy how much to tune my cb he asked what i had and he tells me "oh that one cant be tune" ... i was like hummmm okay and took off with my stuff .... i have been reading here and on the net and there is notting that is tellling me that the 19 cant be tune...

so my question is you guys with a cobra 19 did u guys tune yours ???

is that guys full of B.S and did not want to deal with me ???

:hi:thanks for you help
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Umm tuned radio? Hes gonna hafta tune his antenna you mean... what ya need to do is run over to radio shack and get an SWR meter, they only sell a handful, get the smaller one, its about ohhh 20-40 bucks? I got mine for cheap because it was the store model and i talked the guy into a discount.

You want an SWR between 1 and 1.5

What ya do is basically hook up yer antenna into the SWR meter, then you plug yer cb into it, go to a channel you will use the most (for me i picked 20 because its right by 19 the trucker channel and its smacl in the middle of the 40 channels).

Key up, look at the meter. Whats it at? If its high/low adjust yer antenna. Sure theres a "formula" for cutting X amount of... but with a firestick it should have a little set screw on the top, make it longer by 1/4 of a turn, test yer SWR again, keep that up till you get as low as possible.

Thats how you tune a cb radio for a low SWR. Now you know. Yuo can have a shop do it if its cheap enough, but get yerself an SWR and you can do it free unlimited times.

BTW that was a QUICK instruction briefing, you'll want to read the instructions that come with your SWR meter... heres some info from the web i pulled:

First of all, make sure that all the doors and the trunk are closed. Then, park your car at least 10 yards away from any big buildings, other cars, or trees. Also, make sure no one is standing close to the car. Any of these can mess up the reading. Now, you have to attach the meter in between the antenna and the CB. Using shorter coax cables, attach the antenna to the ANT end of the SWR meter, and the CB to the other end. Now that it is attached, check for the switch on the meter that can be set to FWD or REF. Set it to FWD. Now turn the CB to channel 1, and key the microphone. Adjust the knob labeled SET until the needle reaches full. Now that this is done, turn the switch to REF. Key the microphone again. Record this number, and then switch the CB to channel 40. Key the microphone again, and then record this setting. Very important: The microphone must be the same distance from the meter each time you key it. The objective here is to get the two numbers to a perfect 1:1 ratio. However, as long as the ratio is under around 1.4:1, you will be ok. My CB, after tuning, is now around a 1.1 or 1.2:1. This simply means that the numbers either match or are very close to matching. Now we go on to tuning.

If your SWR reading was higher on channel 40 than it was on channel 1, then it simply means the antenna is too long. If it was higher on channel 1 than it was on channel 40, it is too short. This is really easy to change if you own a tunable-tip antenna. If you own an antenna like this, you can simply unlock the tip and raise or lower the antenna. Continue tuning until you reach a good ratio. If you own a fiberglass whip antenna, it is a little more difficult. First, you have to remove the tip and cut until you can access the wire coil. If it needs to be shortened, you have to begin cutting in around ¼" increments until it is correct. Now, if it is too long, you have to take the top coil and continue moving it out in slight increments until it is correct.
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Basically everybodys right here... i didnt say anything about "tuning" a CB because its not something i think hes gonna be doing. If hes putting a CB in for the first time and doesnt know how to tune it, hes not gonna know about putting an amplifier on a CB radio. Now for those who are curious, CB is mandated (by law, the FCC) to only allow a certain power output. Now its not a whole lotta power and will get you maybe 5-10 miles. What a lot of guys (and usually truckers who are always on the road) do is they hookup an amp to their radio (not yer regular amp for yer stereo lol) to boost the power. Its illegal because your using more power then your licensed for (CB requires no license, to get mre power you need a ham license then yer on a whole new set of frequencies and can talk all over). But they all do it anyway. Its tough for the FCC really to find someone unless a guys giving out exact info.

For your first setup, stay away from amps, you won't need it really. If you plan to use a CB allllll the time and really love it, then look into putting an amp in. Most guys who are into cbs in your area can help you. I dont know if a lot of shops will help you "on the books" because it is illegal. Its not something a cop whos pulling you over can/will right a ticket for, its outside their bounds... but hope that helps ya
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