CB antenna mounting/ground (1 Viewer)

[woytovich]

I'm reinstalling my Wilson stick fiberglass CB antenna after having removed it while doing some work on the truck. Previously it had been installed in the same place for years.

...now that I'm paying more attention I have a question regarding the ground on the antenna.

Should the antenna base be screwed directly to the metal mounting plate or should I be insulating it from the plate? (The mounting plate is grounded through the bumper to the frame etc)

Pictures for reference.

 

[1911]

There should be a thick nylon washer that goes around the stepped landing on the top piece in your hand (in the last picture), that will keep the antenna from being grounded against the mount. The outer coax layer is grounded through the big threads on the PL-259 connector.

 

[woytovich]

So the nylon washer (That I don't have) is "stepped" to insulate the thin shaft of the connector (adapter?) from where in passed through the mounting surface?

 

[woytovich]

washers

 

[woytovich]

 

[1911]

Yes, that's exactly it (the insulated shoulder washer in the diagram).

 

[george_tlc]

Yes, insulating washer. If you look at your antenna bits or use a meter on continuity (to confirm) you will notice that the inside threaded part of the base is insulated from the outside threaded area. Your coax outside shield is ground and the inside conductor is the antenna feed signal. Without the washer you are shorting the coax ground/feed at the antenna base...

So what you are aiming for is: the base of the so239 connector (in your pic above) bolts to the bumper/bracket/ground and the entire antenna is NOT electrically connected to the bumper/bracket/ground. That way the coax shield (grounded at the rig end) is now also grounded right at the bumper/so239 connector and the coax center wire feeds up into the antenna whip.

Without the washer you had a shorted antenna (assuming your weren't lucky and the paint etc prevented a full short)... Bad for the rig and bad for trying to get a signal out or to receive a signal.

cheers,
george.

 

[WB8LBZ]

I'm glad I looked at this, I have at least one mount that has had the insulator deteriorate from the sun and hot weather. I just bought some from eBay, 10 for $4.95 .

Larry in El Paso