CB Antenna tuning help..

[YeaItsSlo]

Okay so i got a cobra 29 radio.. and a fender mounted FireStik Firefly.. and i read alot on the internet about the SWR reading and how it should be under a 1.5.. will i tuned mine in and got channel 1 and 4 equally about 2.0 and 2.1.. so they are close but how do i get the SWR lower? Im using 18 feet of firestik coaxle cable.. is it because of my short antenna? (only 3ft) about 7in of it are above the top of the jeep.. would moving to a 4ft antenna help out my SWR's?

 

[serialphreak]

I used a 4 foot tunable tip one and with 18 feet i had to tune the tip to make the antenna longer slightly to get my swr to 1.5. easy way to know if u need to go longer or shorter is check swr on channel 1 and 40. if its higher swr on 40 than it is on 1, then you need to go shorter, and visa versa.

 

[GSequoia]

It very well could. 2.0:1 will not hurt you though (other than you won't have the best transmitting/receiving distance). You only really have to worry higher than 3:1.

One trick is to go to a truck stop or wherever and get a CB antenna quick disconnect, that extra bit of height can make a LOT of difference.

I assume you have already messed with the screw in tip of the FireStik, yes?

 

[YeaItsSlo]

Oh yea, of course i did... i had to adjust it to get my SWR's close together.. I also planned on getting a spring to see if that brings my SWR's down.. Right now i have prolly a 2 - 3 mile radius of clarity.. id like to step that up to atleast 5 - 6 miles..

 

[GSequoia]

A spring will probably help - I was assuming you had one already (Personally I always run a spring in case I hit low flying aircraft.

 

[YeaItsSlo]

haha.. yea with only a 3ft antenna i figured i wouldnt really be hitting to much... but im going to get one now just to get some height outta this thing...

 

[8Mud]

Another tip, is to close the doors and not to park near a building and/or especially a chain link fence when trying to adjust your SWR's. Coiling up the extra antenna cable can also screw with your SWR's.

 

[YeaItsSlo]

when i checked my SWR's i did it in a huge parking lot away from all poles.. and my coil of extra wire is no bigger then 6in around... so that wont have any effect on the readings.. the coil of wire only comes into effect when its bigger then 10in diameter or so..

 

[WB9YZU]

Okay so i got a cobra 29 radio.. and a fender mounted FireStik Firefly.. and i read alot on the internet about the SWR reading and how it should be under a 1.5.. will i tuned mine in and got channel 1 and 4 equally about 2.0 and 2.1.. so they are close but how do i get the SWR lower? Im using 18 feet of firestik coaxle cable.. is it because of my short antenna? (only 3ft) about 7in of it are above the top of the jeep.. would moving to a 4ft antenna help out my SWR's?

Front fender? or Quarter Panel?

Your antenna has to be clear of the Jeeps body to work. A number of folks use the rear 1/4 to mount their antenna, the body shields it badly and messes with the SWR.

There are fairly detailed instructions on the FireStick site. Personally, I would never run a Firestick on a any Jeep; not even the street driven ones.

Don't worry about getting out too far. Coverage depends on terrain, cover and how much interferance you are getting from stations on the same frequency.

If you are really hung up on the SWR thing, go to a truck stop and pick up an antenna tuner.

 

[YeaItsSlo]

Front fender? or Quarter Panel?

Your antenna has to be clear of the Jeeps body to work. A number of folks use the rear 1/4 to mount their antenna, the body shields it badly and messes with the SWR.

There are fairly detailed instructions on the FireStick site. Personally, I would never run a Firestick on a any Jeep; not even the street driven ones.

Don't worry about getting out too far. Coverage depends on terrain, cover and how much interferance you are getting from stations on the same frequency.

If you are really hung up on the SWR thing, go to a truck stop and pick up an antenna tuner.

I have an antenna tuner.. how else would i know what my SWR's are? Im looking for distance on my jeep so coverage really does matter.. and everyone says that SWR's should be under 1.5.. im not worried about hurting my radio but i do want to get the best possible usage out of it.. Details on why a firestik is bad when it seems the be the number 1 rated antenna for a jeep? My antenna is mounted on the front fender, as stated in the fist post.. just like this one.. this is not my jeep..

 

[8Mud]

when i checked my SWR's i did it in a huge parking lot away from all poles.. and my coil of extra wire is no bigger then 6in around... so that wont have any effect on the readings.. the coil of wire only comes into effect when its bigger then 10in diameter or so..

A lot of it can be trial and error. It's hard to say what will mess with your SWR's enough to cause problems.
Might as well try and rearrange the cable coil just to see what happens.
Funny but you can likely trim your radio antenna and change the SWR's on your CB antenna. As a matter of fact I know you can, I've done it. I always try and get my antenna as close to the center of the vehicle as pratical.
Antenna tuners are often a waste of time. The length of the patch cable can also have an influence. Double check your connectors for cold solder joints and whatnot.
With a slightly higher SWR, it's likely your CB radio is compensating by pushing a little more wattage. A good tune will often lower the wattage output a little, but produce a much cleaner signal. Depends on the design of the finals.
I prefer K-40 antennas, because I've found them to be really easy to tune and durable (I've still got the first one I bought in 1980 or so, I've still got my first CB radio from 1960 or so). Easy to remove for storage (from thieves) and when going through a car wash.
Base load antennas just seem to work better most times IMO.

 

[WB9YZU]

You said "Fender Mounted" not "Front Fender Mounted", so it was a valid question.
I have seen countless Firestick and clones stuck to the rear 1/4 panel and for some reason it won't tune :wow:

I said "Antenna Tuner" not "SWR meter" . An Antenna Tuner is used to match the radio impedance to that of the load (antenna) , a SWR meter only measures SWR or the ratio of outgoing vs returning power.

Firesticks are stiff and do not tune well for the price. They one of the many designs of 5/8 wave antennas that do not provide a 50ohm load at the antenna base. Because of this, you need to be vary careful about not cutting the coax they supply, or making coils of it because the coax is actually the device they use to impedance match the non-50ohm antenna to your radio.

#1 rated antenna for a Jeep? Nah. Works reasonably well on a 18 wheeler when fed with a cophase harness and that's all I'm giving it.

I agree with the base load being a good antenna. I have had good luck with them and everthing above the load is a radiator. I use a Larson NMO baseload (What I had handy) though when I used to work for a CB shop, the K40s just came out and I was impressed as heck with their performance and ease of tuning. I'm running a 4' Barjan antenna on the YJ. It is also a stud mount, but is base loaded. It was also easy to tune and seems to work well for what I want out of it.

BTW: Did you realize that when you started this thread, there were 4 other active CB antenna threads?

 

[serialphreak]

heres where i mounted mine with a spring and 4ft firestik II 18ft cable to get 1.5 SWR. You can see my old ball mount on attached to the rear quarter and i couldnt get good SWR there. so i moved it to the place you see my antenna now and its working much better.

 

[YeaItsSlo]

You said "Fender Mounted" not "Front Fender Mounted", so it was a valid question.


BTW: Did you realize that when you started this thread, there were 4 other active CB antenna threads?

party1:

 

[RTicUL8]

I've tested SWR on five spots on my jeep.
Note: Using a 4' Wilson adjustible.

1) Rear bumper...poor signal.

2) Right rear quarter...(using a ball - exactly like serialphreak's picture)...poor signal.

3) Driver's fender...(where you said you have yours)....moderate signal.

4) Roof....best signal.

5) Top of ARB bull bar (Front bumper)....also a great signal.

I also feel that the quality of the cable can affect the signal too.
Use coax with a bare copper braid and stay away from the cheap tin or aluminum braid.

Make sure you run a power cable (with an inline 30amp fuse) straight from the battery to your CB. Don't go thru the fuse panel or tap into anything else. Route the power cord away from the ignition or you will get engine noise.
Body ground is okay.

 

[scoobyxj]

I must be lucky then. I have a decent signal (is around 1.8 IIRC) from the side of my Jeep, running a 4" Firestik. I have been thinking moving though to the roof though not because of signal, but to remove the ball mount from the side.

 

[RTicUL8]

I must be lucky then. I have a decent signal (is around 1.8 IIRC) from the side of my Jeep, running a 4" Firestik. I have been thinking moving though to the roof though not because of signal, but to remove the ball mount from the side.

It's been my experience (but not everyone's) that if a part of the antenna is beside the body, that it causes some signal loss.
Did you test SWR 360° around you Jeep?

When I had mine mounted on the side, I had more loss when standing on the driver's side of the vehicle.

===

Funnay story: I pulled up to work one day (with my antenna off) and noticed that one girl at work was just staring at my jeep. I thought it was the usual "snorkel stare," but after several minutes, she said "Why do you have a doorknob on your car?" :laugh3:

 

[pma4x4]

Generally speaking, 2.0:1 is good enough to not do damage to the radio. I right now am having to relocate my CB antenna just due to I cant get it any lower then 2.3 I have tried multiple tunable antennas and using a Frequency counter with a built in tuner i borrowed from another ham. I am relocating it to the roof rack i just installed.

Its best to have the longest antenna possible. CB is a 11 meter wave lentgh meaning a true full WL antenna would have to be 33 feet tall. well that wont work so the best really are those 9 foot "whips" that are a "quater wave". The shorter the antenna the more you are "faking out" the signal thinking its a longer antenna.

thing you need to check
1 is the body grounded good?
2 is the antanna mount grounded good?
3 is the antenna a bottom load or top load?
dont know where the load is? look for a tight coil of wiring on the antenna if its at the bottom the body fo the jeep may interfere with it.
4 are you using good coax cable. for long runs in vehicles i always use RG-8 Mini its alot better then the RG-58 you get most of the time.

5 if you are using a spring make sure its the large bulb shaped ones and not the 3/4" ones. The small ones most use the ends on them are just press in and there is no cable soldered to each end. I have seen alot of these flex to the point of seperating then you have no anteanna. The bulb shaped ones have a soldered HD wire from top to bottem so you know is connected good.

If you do mount the antenna to a roof rack make sure you run a flat braided ground cable from the rack to the body to ensure a good grounding. Hi SWR and lack of grounding will fry upa radio quick.

If you want a equal amount of TX/RX then you will want to mount it in the middle of the top of the jeep. If you mount is on the pass. rear most of your signal will come in thru the drivers side front, but this is not much loss. Nice thing about this is if you ever play fox & hound with a Cobra 29 you can detune the rig and drive in a circle to locate the fox signal.

the Cobra 29 is a good all around rig. just get the antenna tuned and your good for miles.

My 2M antenna for HAM radio is ball mounted on the DS of the rear panel and that tuned up to 1.2 on the SWR but when you get into HF frequencies it gets a bit harder to tune.

When you do tune for SWR tune in the middle of the band, being cb should be channel 19/20. or at 27.085mhz (IIRC).

Hope this helps and hope i didnt confuse you too much.