CB tuning

[BurbanAZ]

I want to start getting some communication on my truck and i figured since i dont know anything about radio, id start with a CB. I ordered a Cobra 18wxst2, 4' Firestick tunable, stud to mount it, and fabbed up a little bracket to mount it on my front bumper. I mounted it there because that way its not as likely to get broken off since i already have height issues with my suburban, with another 4' on top i dont think the antenna would have lasted long. Since im completely new to radio im not sure how to tune it, or check that im getting the best signal possible. Any pointers?

 

[jaxs1984]

You really need to tune it with an SWR. That way you would know 100% if its installed properly. If not it can damage your CB. The main concerns would be proper grounding of the antena mount, the antena height if its tunable and the running of the cable to your cb.

You can get a cheap SWR at Amazon or your local Radio Shack
http://www.amazon.com/gp/product/B0...&pf_rd_t=101&pf_rd_p=470938631&pf_rd_i=507846

Here is a good link explaining howto use your SWR and the techno mumbo jumbo.
http://www.firestik.com/Tech_Docs/Setting_SWR.htm

 

[BurbanAZ]

since grounding is the main worry, can i run a ground cable or strap from the antenna stud to ground it? Ill order a SWR

 

[jaxs1984]

since grounding is the main worry, can i run a ground cable or strap from the antenna stud to ground it? Ill order a SWR

You can do that, depending on what type of bumper you have you might be able to ground it there or the frame of your car. Some people who mount it to their swing out tire-carriers have problems mounting it to the tire-carrier cause the swivel has some type of "washer" which is not metal on metal , etc.. Depending on your mount you created , it might already be grounded. The SWR would tell you for sure. Just make sure the wire is 18ga. Another thing is that depending on the mount you created to your bumper , it might not make good contact because of powder coating, etc.. Some have good results of scraping off some paint to the bare metal. I can't tell from your pic how it is mounted.

But, before you do anything, take a reading with the SWR and if its in "range" then nothing else should be done on your part. If its in the RED RED on channel 1 19 and 40 then work backwards and eliminate/ add stuff remeasure and repeat.

 

[Finlay]

since grounding is the main worry, can i run a ground cable or strap from the antenna stud to ground it? Ill order a SWR

If you have a continuity tester, you can see if it is grounded already by way of being bolted on to the bumper.

That location isn't the best - a hood lip mount might work a bit better - but it will be workable.

Tuning that antenna is dead simple. It will be easiest if you start from the "bottom" - loosen the keeper nut a bit, and screw the adjustment screw all the way down. That screw has a little mark on it. Go whole turns until you get the lowest possible SWR on each of channel 1,19, and 40. It can take a fair amount of experimentation, and I bet you'll need 7-8 turns to get there.

Good luck and good work on the bracket fab and install. It's very clean.

 

[BurbanAZ]

the bumper should be grounded, when i made the bumper i made it so it basically slides into the frame rails and bolts in place, then has a subframe under the outer part of the bumper. The bumper does have bed liner on it though so that may mess up ground for the antenna. I ordered a SWR meter from amazon so once i get that here ill check and adjust from there.

 

[Tennmogger]

Hope you ordered a "low" SWR, not a high one. If not, then you still need a meter to measure SWR with! Yeah, my wife already called me a smartazz this morning...

Bob WB4ETT

 

[BurbanAZ]

Hope you ordered a "low" SWR, not a high one. If not, then you still need a meter to measure SWR with! Yeah, my wife already called me a smartazz this morning...

Bob WB4ETT

I have no idea what your talking about lol, I ordered this one http://www.amazon.com/gp/product/B002KRME3C/ref=oh_details_o01_s00_i00

 

[Tennmogger]

Oh, I was just poking fun at the tendency of non-hams (and regrettably, some hams) to refer to an SWR METER as an SWR (standing wave ratio). In other words, you can't buy an SWR, but you can buy an SWR meter. Same thing with using the term HAM referring to ham radio equipment, as in "I installed my HAM into my car" would sound rather uninformed to most ham radio operators.

That SWR meter you have ordered should do the job just fine.

 

[BurbanAZ]

Ok i got my SWR meter and went out to try and tune it. The SWR was really high like 4 on channel 40 and on channel 1. I figured the antenna needed to be grounded so i added a 6 gauge ground cable from the antenna to my main battery. I tried it again and im still getting the same thing. Any idea what it might be? Also do i need to be out in the open to tune it? i was just in my driveway. Heres a video of how i was doing it.

 

[Finlay]

Ok i got my SWR meter and went out to try and tune it. The SWR was really high like 4 on channel 40 and on channel 1. I figured the antenna needed to be grounded so i added a 6 gauge ground cable from the antenna to my main battery. I tried it again and im still getting the same thing. Any idea what it might be? Also do i need to be out in the open to tune it? i was just in my driveway.

It will help if you aren't near any structures while doing it, yes.

That antenna you have has a tunable tip. Pull the plastic tip off (this may take some doing), and there is a little screw with a lock screw. Loosen the lock screw a bit and you can rotate the tuning screw up and down. Turn the screw all the way to the bottom, tighten the lock and replace the cover. Then test your SWR at 1, 19 and 40. Maybe write the results down.

Then remove the tip, loosen the lock screw, turn the tuning screw one revolution (there should be a mark on it to help), tighten the lock screw, replace the tip and test again.

Wash, rinse, repeat until you get SWR values that are acceptable. I think you can get about 20 turns out of that tuning screw, so there is lots of adjustment.

 

[BurbanAZ]

i went to an open area and it seemed a little better, but ill mess with tuning the antenna itself now and see. I read about it maybe messing up your radio if its too high if its just over 3 am i going to cause any damage keying the mic a bunch of times to tune it?

 

[Finlay]

If you try to talk, you could burn out the transmitter. Just keying the mike won't hurt anything.

 

[BurbanAZ]

If you try to talk, you could burn out the transmitter. Just keying the mike won't hurt anything.

ok good to know. I went to an open area, went through the whole range of adjustment (which was alot a turn at a time) and it made no difference. channels 1, 19, and 40 are all still over 3. channel 40 is lowest just over 3 and 1 is highest probably around 3.3 or so. Also i just ran the ground that i added to the neg battery, should i ground it to the block or frame instead or does it even make a difference?

 

[jaxs1984]

Ok i got my SWR meter and went out to try and tune it. The SWR was really high like 4 on channel 40 and on channel 1. I figured the antenna needed to be grounded so i added a 6 gauge ground cable from the antenna to my main battery. I tried it again and im still getting the same thing. Any idea what it might be? Also do i need to be out in the open to tune it? i was just in my driveway. Heres a video of how i was doing it.

I think the ground cable needs to be atleast 12GA and the ground cable goes from the antena mount to the chasis.
http://www.firestik.com/Tech_Docs/Mnt-Grnd.htm