CB antenna SWR issue.

[LibertyOrDeath]

I got a spare 2' Firestix II antenna recently and I cannot seem to set the SWR on it. No matter what I try it is almost always in the red zone around the 3.5:1 area. This is what FireStix.com says about that.

If SWR is in the "red zone" on all channels, you probably have an electrical short in your coax connectors, or your mounting stud was installed incorrectly and is shorted. DO NOT USE YOUR RADIO UNTIL YOU HAVE FOUND THE PROBLEM.

The 4' antenna I have 1.2:1 and works fine.

When I disconnect the antenna from the back of the CB, the CB shuts off, as if the CB is grounded by the antenna. Is that the issue or is that normal.

Any ideas.

 

[al7fi]

I think you have two problems going on. Because the antenna mount goes to your vehicle ground (the other half of your antenna), you are providing a path for DC ground. Do you have the black wire (ground or negative) connected to a good ground (body, sheet metal or even better a ground at the battery?, If not you really should. However that is not what is causing your problem. Your radio should work without an antenna connected as in it should turn off and on regardless of the antenna. Disconnect your coax at the radio, use a volt/ohm meter to check for a connection between the center pin and the ring of the connector. There should not be one, that is infinite ohms. Since the 4' firestik is OK, I suspect there is a problem with the 2' one. If I remember right they are helically wound 1\4 wave antennas. That is there is 1/4 wave (about 109") of wire wound around the fiberglass core. If there is a break in that wire, you could get what you are seeing (it would be too short). You can check that with the ohm meter also by testing between the threaded portion and the wire end at the tip. You should show low to no ohms. Hope this is of some help to you. I am familiar with that antenna concept, since I use one that is wound with enough wire for me to tune from 3.5 Mhz to 30 Mhz (it is adjustable, but that is another story). Good luck.

 

[Corwyyn]

The high SWR might also be due to antenna location, for instance if you have your antenna mounted on the swing gate or off the rear by the tail light (two popular locations) it may be that the antenna is too close to the metal of the body which is helping reflect part of the signal back into the system. You might not notice this with the 4' antenna since more of it extends up in the clear. Just something else to consider.

AL7FI, is your's an Outbacker or something similar? Just curious.

 

[al7fi]

NO, not even close. It is a Webster Bandspanner from the 50s. Has not been made for a long time. Actually have 2 of them. Got one in Biloxi, MS when I was stationed there and used it on my 74 Cherokee and later on my 84 XJ. The owners manual (2 pages) shows it mounted on the rear bumper of a 55/6 Fairlane with dual exhausts using a chain clamp mount. It is essentially a manual version (original) of the screwdriver types. To change bands you loosen a clamp on the steel whip and move it (attached to a wiper riding inside the fiberglass tube) up or down to a premarked location. The tube has slots cut along its length so that the wire wrapped around the tube penetrates the tube. This is where the slider contacts it. You can still find references to it on the web. Sorry, do not have an address, but Google "Webster Bandspanner". Two versions (I have one of each), one has a longer fiberglass tube but same amount of wire, to get the coil portion above the metal of the care.

Regarding the OP problem, he said he had a 4 footer that was fine, so I am guessing it is not a problem with proximity in this case. Course no information on the location was provided.

AD5VG de AL7FI (ex WD5BHO) 73

 

[LibertyOrDeath]

Driver's Side

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Passenger Side

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[al7fi]

I would think that the location and the manner in which it is mounted would NOT be an issue re high SWR. Do you use the shock spring for both of the antennas? While not overly likely, the extra length could be your problem. If you do not use it with the 4 footer, try taking it out of line with the 2 footer, and check the SWR again.

 

[kb0nly]

Sounds like you have a bad ground from the radio to the body if your radio shuts off when you remove the antenna...