Installing CB Antennas

 

Submitted By: Sparkz

Basic Installation of 10-11 meter 50 ohm Antennas

Install an S.W.R. meter between radio & antenna using 3’ coax cable.

(SWR Meter)

1. If the S.W.R. is high on CH.1 the antenna is short and must be lengthen

2. If the S.W.R. is low on CH.40 the antenna is to long and must be shortened {Take your time 1.5:1 is acceptable but try for perfect}

3. If S.W.R. below 2:1 is not obtainable the impedance could be other than 50 ohms {It may be possible to ground the antenna to lower resonant frequency & start over}

4. Best operation in mobile is located on roof and  in center of vehicle

5. 2nd best operation is at least 2/3rds of antenna above highest part of vehicle

6. Excess coax should not be coiled { this creates a “ choke” within the cable }
Random stuffing in of cable is preferred

7. If you see 3.0:1 S.W.R across the entire band check for proper ground connection  

8. If your install is mobile 18’ is recommend length or coax  

9. If your antenna has a rubber cover over be sure to replace it to check S.W.R.

10. If your antenna is mobile make sure all doors are closed and vehicle is away from trees , buildings , power lines or other metallic objects { i.e. signs , cars, trucks, trailers }

11. For fiberglass mounts use a metallic plate on bottom of antenna mount and run an artificial ground to chassis {this should afford the antenna to perform properly }

12. Some newer truck mirrors have a clear coat that may seem to but does not provide a sufficient ground for antenna operation { you may have to run a artificial ground to the body or chassis do not ground to door as it will not provide a sufficient ground }

13. Do not attempt to tune your antenna in the rain or when its wet { as it will give false readings }

14. Use a conductive grease on all connections sparingly  { silicone or petroleum jelly will work if no conductive grease is available }

Basic base station grounding & bonding

Per: 96- NFPA 70 – 810-1,810-20,810-21,810-52,810-53,810-54,810-70,810-71

Do your self and your radio / equipment a favor:

1. Always ground your antenna mast not the tower for lighting.

Using not less than a minimum #10 awg. Copper wire run as straight and short as possible with out any unnecessary or sharp bends {using tape or ty-raps to tower for support you must use 3” min. insulated standoffs to mount cable to a building so try to avoid this path} to a driven ground rod or made electrode using an approved connector.

2. Install a discharge unit {static discharge block} located outside of building Run a continuous # 12 awg. Minimum copper wire run as strait and with out unnecessary or sharp bends to the driven ground rod / electrode. Using an approved connector {this will reduce the chances of a static build up and resulting spike}

3. Bond all metallic equipment { radio & amplifiers chassis } together using not less then # 14 awg copper wire and than to ac ground system { pipe } or electrode system { rod }

4. Electrode system & ac equipment ground system must be bonded together using not less than a # 6 awg. Minimum copper cable install using approved connectors { this will clamp most any transient voltage spikes or static build up and increase the integrity of the system and is required nfpa 70 }

5. Keep lead-in conductor { coax } a minimum of 4” separation from all other conductors.

6. Install an antenna switch run 1 pole of switch to ground system. and switch when radio is not is not in use. { this will help in the event of a lighting strike & static discharge } used this way is the smartest way to use an antenna switch.

7. Minimum size of lead in conductor {coax }

#14 Awg. Less than 150’

#10 Awg . over 150’

NFPA 70 / T810-52