RTH: Basic CB antenna question

[96r50]

Before I fry anything, I just want to double check something. The CB antenna I have (Wilson fibreglass) has a wire with an eyelet on the end of it. Is this supposed to be ground to the mount/truck body? Thanks!

 

[Miescha]

Sounds like you are using a two-terminal coax (see pic below). In short, yes - the seperate ground terminal goes to your vehicle ground (frame, battery neg).

The longer version: the second ground ring basically takes the braided ground shielding and routes it to the terminal ring rather than the outside of the PL259 connector. This is usually unnecessary and inconvenient as you now have a second loose wire to connect. However, this is a plus when mounting your antenna at a location with little or no DC ground (front or rear bumpers for example) since the PL259 will not be getting a DC ground from the mounting point.

You will still want to check for continuity when you're done. See the chart below.

Legal Disclaimer: I'm sure I stole . . . er . . . borrowed this image from an antenna site somewhere or maybe it came with one of my antennas - I don't recall but the image is certainly not created by me and I'm not claiming it is mine, I just don't know where to give credit (so don't ask).

 

[alia176]

An excellent reply, thanks!

 

[96r50]

Hey Miescha,

I am actually using the coax with the PL259 connectors. The terminal ring I am referring to is attached to the antenna. The antenna is a 4' Wilson Flex Wilson Antenna - Fiberglass. And while looking up the antenna on the Wilson site, I also found my answer. Wilson Antenna Tech support - Fiberglass SWR Notes It is an impedance wire. From what I understand, I don't ground it unless I cant get my SWR below 2.0:1

1. What is that wire at the bottom?
Wilson's exclusive impedance matching transformer is connected through the external wire at the bottom of the FGT and Flex series of antennas. It is NOT a "ground wire" to increase the ground of the antenna, although using the lead does make the antenna DC ground. It is used when you are not able to get below a 2.0:1 SWR even after tuning. This generally indicates a mismatch of impedance between the coax and the antenna. This can be caused by poor ground but is generally attributed to the mounting location. It re-inserts 25 ohms impedance at the antenna feed point and brings the system back to the 50 ohms required. It is not a tunable device, therefore it is not fooling the radio into thinking the system is matched. It is actually matching the antenna and feed point to the required 50 ohms impedance for the coaxial cable. The most often time it will be used is when the antenna is mounted on the top of tool box in the bed of a pick-up, or on the passenger side of a tractor using co-phased antennas.

2. What if I do not need the impedance wire?
You have the choice of either cutting it off or taping it out of the way. In making your choice, consider if you may move the antenna to another vehicle, that installation might require the lead. For the most versatile use of the lead, simply lay it alongside the fiberglass and tape it in place. Using electrical tape will offer the easiest method and offer the best protection against weathering conditions.

Thanks for the help! BTW, your diagram is from Firestik