CB radio

[MYT HI]

Me Andy my friend installed out radios last night only to find his only has a range of about 100 feet. Anyone know what can cause that? He has 2 whips both functional that are 4 feet long and I have 1 about. 3.5 feet.. Mine works fine.


Sent from underneath my truck

 

[lkfldredneck]

Dual whips act against eachother and get less reception sometimes. I have duals but ones setup to be FM radio and the other is CB. I have gotten people in louisiana before and thats being in canada. If theyre tunable tip, get a tester and hook it up inline and tune it for better reception. Other than that, might have to do the dual whip but only one hooked up

Sent from my finally running z71

 

[IOWNJUNK]

Take it to a cb shop or a radio shack, have it tuned on a meter, ten bucks well spent.

 

[great white]

I need a bit more info than that.

Size and type of antenna?

Where are they mounted?

How are they mounted?

Type of coax?

Termination ends on the coax?

How is the coax routed?

Did you coil up any coax?

Was the SWR adjusted to within limits? (FYI: transmitting with too high an SWR with fry the radio eventually)

Etc....

What you have posted up for a recommendation is like saying "the engine is broken, tell me how to fix it."

Installing a Cb is not like changing a tire. It needs to be installed and adjusted correctly for the best performance.

Twin antennas will not "fight" each other. It's a co phased array that you're trying to build with twin antennas and it makes them directional front to rear if done right. However, they need to be 8 feet apart to work that way and you can't mount like that on a regular pickup.

Twins antenna are just for looks, if you like that sort of thing.

Any one tells you different they are full of sh!te.

The absolute best place to mount a 27 Mhz antenna for the best receive/transmit is a single in the dead center middle of the roof. That will give you the full 12-15 mile range your 4-5 watts is theoretically possible of. Most guys think their radio is fine until I talk to them. They are amazed when I say I can get 20-ish miles in the right conditions. They are usually getting 2-5 miles and think it's "good". A decent setup should get at least 10 miles and that is all pretty much in the antenna setup and adjustment. Even a multibuck radio will be crap with a poor antenna and setup. A 30 dollar radio can get out an easy 10-12 miles with a good antenna and setup. They pee themselves when I fire up the 250W "footwarmer" I have in the truck. A linear amplifier is iillegal by the way, so take your chances. I have one for the very remote areas I end up in and never use it anywhere else.

I also have an HF hand held that I can hit the repeater system and nearly talk to anyone, anywhere if I end up in sh!te outside of cell coverage. Yup, places do still exist without cell coverage. It's an "offshore" model that allows me to program it myself. Handy for driving logging roads or talking to others on FRS/GMRS when they are with us.

Receive can be as far away as europe if the skip is just right.

 

[96k1500]

Like great white said best place to mount an antenna is dead center on top of the cab, mounting it to the bed rails reduces affective Ness because the metal of the cab blocks part of the signal, also if there is any coil in the coax it will cause interference, on a pickup single antenna is better than dual but if you want duals just connect one

 

[great white]

Like great white said best place to mount an antenna is dead center on top of the cab, mounting it to the bed rails reduces affective Ness because the metal of the cab blocks part of the signal, also if there is any coil in the coax it will cause interference, on a pickup single antenna is better than dual but if you want duals just connect one

Well, yes.....and no.

Mounting close to the cab on the bed rail does "shield" some of the antenna, but far more important is how much of it is above the cab, how the antenna is constructed, how much metal is underneath the antenna and the most important of all is the RF grounding.

"Height makes might" in antennas for sure, but so does the mass underneath it.

An antenna needs a "ground" underneath it. It laymans terms: the body of the vehicle is the second part of the radiating antenna.

The signal will be stronger to where the largest mass of the body is and weaker where there is less. mounting to one side or to the front of back makes the antenna more directional in the plain where the most metal is. That's a bit complicated to grasp from words, so this picture might help understanding:

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This is why I recommended the absolute best location as the top center of the cab roof. Well, more accurately it would be the center rear I guess. You are trying to get the antenna in the exact center of mass.

Another fact most don't realize is that ALL cb antennas are 102" long. That has to do with the wave length. It has to be 102 in order to pick up 27Mhz.

A 3 foot antenna is a 102 antenna wrapped around a fiberglass core. A Wilson or K40 base load antenna has the 102" coiled up in that big base mount. the shorter the antenna, the closer the wire is coiled, the shorter the wire is coiled, the lower the performance.

Where the coil is placed also makes a difference. For Example: I use a 5 foot Wilson Silverload antenna. It is called a "top load" antenna. Meaning the majority of the coil it near the top of that 5 feet. This means the most compromised part of the 102" is as far up as possible, which somewhat mitigates the compromise of having a coil.

you can have top, center and base loading antennas with associated compromises with each.

RF grounding is also NOT like DC power grounding. RF grounding is "skin effect". Meaning, the width of the ground is the important factor. That's why copper braid is used for it. Much like the ground that goes to the hood of the vehicle. The hood is grounded this way because it is the large radiating surface nest to the AM/FM radio antenna in the car. The Am in your dash radio is the same principle as the Am in your CB....except in this case we're making the hood an effective part of the receiver and taking any induced noise away with the RF ground.

Radio theory can make you head hurt really quick....

 

[df2x4]

From someone who likes electronics but knows little to nothing about radio transmission, thanks for this post. So much good knowledge there.

 

[MYT HI]

We determined it to be something between his antenna and the time it gets to the radio, bad ground maybe


Sent from underneath my truck

 

[-sin-]

Great White - GREAT info posted here!

You mentioned "coiled up coax", I have about a foot coiled up under my rear bumper. Would that effect anything?

 

[Ruger_556]

We determined it to be something between his antenna and the time it gets to the radio, bad ground maybe


Sent from underneath my truck

Does your coax use a solder'd end? My buddy did mine when I put my CB in and I couldn't reach out past 100 yds. After much I checked the coax and ended up re-soldering the end. Works great now!