General rules for CB mobile aerials.

[Paul]

For the mobile CB user there is a wide choice of aerials.
Most designs claim to be better then the other but simple facts apply to all of them.

Aerial Length
UK only CB aerials are NOT suitable for mutinational CB sets. THey are all too short. Always fit the longest aerial you can. The optimal length is 3 meters. This is not possible or safe on a car so manufacturers shorten them making up the difference in length by introducing a coil which takes up less room.
Generally the less the length, the greater the ground plane (metal roof) you'll need so if you own a plastic car, whoops, you've got a problem. There is a type of aerial that will work on a plastic pig of a car and that's a marine or Non Ground Plane aerials. NGP aerials usually come as a kit.
NEVER CUT THE COAX ON A NGP LEAD!
The shorter the aerial the less chance it will effectively work over all 80 channels i.e. European (CEPT/ EU) and UK channels.

The higher the better.
Coiled types should have their coil above the roof-line of the vehicle.
Two-thirds of the antenna should be above the roof-line.
The aerial mount be well-grounded unless it is a magnetic type.

Hole or screw on body panel mounts
If you use these mounts you must make sure they make good metal to metal contact. Sometimes this is not possible and you should use shortest length of heavy duty wire to the nearest earth point.

Magnetic Mounts
Tip, put a simple layer of plastic sheet between the magnet and the body work. More powerful mounts can't be pulled off cleanly and sliding a magmount can scratch modern paint finishes. The Plastic will allow you to 'tilt' or 'tip' the magmount without scratches.

Aerial Types in order of efficiency
Top-loaded CB aerials i.e. coil wound fibreglass aerials with a tunable tip are the most efficient type of aerial.
Centre-Loaded. Coil in the middle (ish) of the antenna more efficient than base loaded types.
Base loaded including magnetic ring types are the least efficient. These types generally can handle lots of power but must be mounted HIGHER than any metal body work.

Cable lengths and routing
Poor Routing and incorrect coiling of excess coax i.e. Too Tight a bend stresses and breaks coax.
Coiling is bad. Its better to serpentine the cable into a 12 to 18 inch yarn-like skein, loose tie it in the middle, then conceal the excess.
Avoid crushing cable. ANY damage will change the effectiveness of the lead.
Always seal joints and connectors with a silicon seal. water ingress is bad news. Don't forget to seal the base of the aerial connector.

[Lightspeed]

Excellent information Paul :-)

Re mag mounts I will add a word of warning. I was lent a 3 x 5inch magmount by a friend. I positioned it over the roof of my car and.... CLUNK! the thing locked on very securely....

Unfortunately so securely in fact that it took nearly a month to devise a way to get the brute off and even then the paint of the car was damaged!

So beware of triple mag mounts they can seriously damage your vehicle!

[Paul]

I used to have that very problem until i started cutting circles of thick plastic sheet to put under the mount.
If you over size them by a couple of inches or even make them oval thus sticking out on only two sides, lifting just one tab and an assist with the aerial base is usually sufficient to "unlock" the mount.

I could never see the point of triples. I've run a 2m firestick (which old time CB'ers know is a heavy old beast) on a 5" magmount and never lost it once after years of motorway driving.

[Lightspeed]

Yes the triiples only real use is to extract cash from the pockets of the unweary.

I eventually had to tap a 3/8 thread onto a steel rod and then leverage the horrible thing off with that.... I'm very lucky taht it didn't dent the roof in the process!

[Skean Dhude]

I used a piece of thick felt. It stopped the scratches and you could put a screwdriver in to lever it off. I wanted that solid thunk as at that time I drove like a maniac.

[Lightspeed]

(30 July 2012, 15:13)Skean Dhude Wrote: I used a piece of thick felt. It stopped the scratches and you could put a screwdriver in to lever it off. I wanted that solid thunk as at that time I drove like a maniac.