CB SWR Reading HIGH

Yes and no. IF the length of coax affects the SWR then you have a problem. While the coax has a shield, RF can and will end up on that shield if the antenna system isn't installed properly or isn't resonant. In most cases, however, coiling the coax should have no affect and can actually be a good thing because it creates a common mode choke - which will cancel out any RF on the shield of the coax and make ferrite chokes unnecessary. Although, this is most effective when the coil is at the feedpoint of the antenna.

 

http://www.arrl.org/files/file/Technology/tis/info/pdf/0683033.pdf

 

Add a piece of coax the the bottom of the ant.Put on where the coax that goes to the radio goes.Couple of feet,then cut short piece's off,and watch your swr's.Sometimes,just adding the coax does the trick.I wouldn't want mine at 3,always get mine down around 1.5,or lower.Have to work at it sometimes,but it's worth it.

 

WTF is going on in here?

 

Firesticks are okay. My main problem with them is "false advertising." They claim all their antennas are 5/8 wave regardless of how long the antenna is (3/4 wave for the 7 ft model). Now, technically speaking, this is true because they use a 5/8 wave length piece of wire. However, it's only electrically 5/8 wave. Because this wire is helically wound around the antenna, it's physically a 1/4 wave (7 ft model) or less and that's what the radio waves are going to care about. This means the longer the antenna - the better the performance. Magnet mount antennas are kind of the same concept. They use a 1/4 wave length of conductor...most of this is coiled at the base of the antenna in the "can" and is referred to as a loading coil. This makes the radio happy because electrically speaking the antenna is a 1/4 wave length and presents a 50 ohm load, but physically it isn't and will suffer in performance. That's why, for the money, the 102" stainless steel whip is the best performing antenna around - it's both electrically and physically 1/4 wave length. Naturally, not everyone wants to put such a big antenna on their vehicle.

 

This^ a 1/4 wave antenna on 11 meters is 108" long anything else is a compromise. The main reason they use 5/8 wave is because the 1/2 wave would present an impedance of about a 1,000 ohms where as they can wind enough wire around the stick and matching to reduce it to something closer to 50 ohms. A 1/4 wave antenna is a lot closer to 50 ohms. I have used the firestick type antennas on different bands with mixed results basically I was not impressed yes they work but. Unfortunately without knowing what frequency the antenna is resonate on (not the radio frequency but the antenna) you have no idea if it’s too long or too short and a SWR meter will not tell you that. If you have to raze the antenna to bring the SWR down it’s too short if you shorten it and the SWR comes down it’s too long it happens pretty fast so just do a little bit at a time but if you are not even close you have no ideal wither it’s short or long. If you have to add coax to make it come down the antenna is not resonate. If you get no match even 3 to 1 there is something wrong with the install or the antenna. A good 3 hour install with attention to details is far better than 10 hours of trying to get a bad install to work placement has an effect, height above the cab really good antenna connections proper grounding at the antenna base meaning coax grounding the metal in the truck body and frame will take care of your ground plane as long as the ground is good at the feed point.

 

Mmmm Antenna resonance

 

That is cool, can you post a few more pictures on a different link to no hijack this./
I really like it and was thinking about something like that for a rod rack and storage for surf fishing at the beach.
Something that sets on the rails and can be removed and installed, maybe not used year around.
May get someone that builds the rod racks to build one from alloy or something making it lighter./
Info on weight, tube used, mounting and so on.

 

so maybe some one has a quick solution to this problem,

my cb transmits VERY VERY quietly. Like to the point I have to scream into the mic for people to hear me, and when im in a group about half the people can hear me. I have a cobra 18 with a 4' fire stick and the antenna mounted to the bed rail (its a 1st gen so its actually metal). When I tuned it 1 and 40 were pretty dam close. When I tried to fix the problem I ran a ground wire directly to the frame, re ran power wires directly to the battery, and swapped mics with people and still no luck. Any idea? I'm thinking the cb is just broken.

 

I'm going with the radio pooped the bed. CB's are finicky little bastards. I would say maybe take it to a shop if you have one near so they can test it. Some places will test for free then go from there.

 

Myth #1 bed rails are not grounded.
Myth #2 you need an extra wire to the frame.
Myth #3 adding coax brings down the SWR and makes the antenna resonate.
Myth # 4 the mount/extra grounding makes up the ground plane.
The bed rails are well grounded they are not bolted to plastic.
If you have a good ground at your mount no extra wire is needed it is a coax ground.
If extra coax brings down your SWR the antenna is not resonant.
The ground plane is the metal parts of the truck including the frame work, the plastic bed has little effect.
I have made contacts in over a 100 countries and every corner of the US mobile granted it is not CB but the antennas work exactly the same. My antenna is motorized it moves up and down electrically to tune it on different bands it will tune from 10 to 80 meters. You can have one of your very own for around $400. The mount is a standard ball mount it is bolted to the sheet metal and the coax is ground to it. The upper mount has no uses other than to keep the antenna from vibrating the black parts are Lexan the antenna cannot be grounded anywhere.

 

The thing is - if adding coax affects your SWR, the antenna isn't working properly. The length of coax should have absolutely no affect on the SWR.

 

The thing is - for co-phasing to truly work, the antennas need to be 1/4 wave length apart (8 ft). You might be getting some directivity out of it...but I don't think it'll be enough to really notice.

 

Must be a 2M antenna that's a little long.

 

I don't think this is an issue with SWR. It sounds like the mic gain on the radio simply isn't high enough or the mic has a problem.

 

Looks like a Little Tarheel. I have one myself that I plan to install with an Icom IC-7000. I plan to take the video output of the 7000 and feed it into my Kenwood DNX-9980HD so I can have the display of the radio show up on the stereo.

 

popped the bed? ill see if i can get it tested.

i dont think its the swr either, i was just posting because its a some what related thread.

can I fix the mic gain? It has a dial for gain, and i have played with that and no change, and i have used 2 other mics and it had the same result, super quiet.

 

That's a CAP freq. flying in your truck?

 

If you have no big need for 6 meters I would highly recommend ditching the short stinger and go with the 56" whip it will make a world of difference. Mine actually will tune on 160 meters but that is really pushing the limits of the coil so 80 meters is good enough for me. That's right the 7000 does have video out that sounds like a neat ideal I run my old Icom 737 at the house remote with my Android the mobile is a 706 mk2 G.

 

Is this the Cobra 18 WX ST? The ones I've looked at don't have any kind of gain control. My guess is, however, that the gain control on your radio affects the strength of the received signal but I could be wrong on that. If other mics have no affect, I think an adjustment needs to be made on the inside. I'll have to see if there are any mods for that radio.