2950 help...... opinions

If it new,contact Ranger for warranty repair:

[h=3]WARRANTY INFORMATION[/h]​

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All Ranger CB and Amateur radios have a 2 year limited warranty. Limited" means that we will repair problems that are caused by factory defects, at no charge. Ranger reserves the right to void a warranty or make reasonable charges for the repair of a product which displays evidence of misuse, abuse, neglect, missing serial number, or modification of the basic design. This is limited to the radio only.

• A Return Authorization Number must be obtained from Ranger before any returns for warranty repair will be
  accepted. Please click here to email us for a return authorization number and service center address.
  
  [email protected]
  
  

• Attach a detailed letter explaining the problems you are having with the radio. The more information you can provide, the easier it will be for the technician to locate the problem. Please include your name, return address and phone number.
  
  
  
• You must enclose a copy of your receipt or proof of purchase. Please retain the original receipt for your records.
  
  
• Ensure that the radio is properly packed to prevent any damage to it during transit. It is the shipper's responsibility to make sure that the radio is shipped safely. Shipping and insurance charges are shipper's responsibility. You must write the Return Authorization Number on the outside of the box.

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If you've still got that barefoot Cobra 19 around, take a minute and hook it up to that new coax and antenna that the CB shop installed and see if that radio (or some other radio) will work through them. It's possible that they did something wrong in their install that still shows as an OK SWR but is not an efficient radiator. If a second radio doesn't work on their installed antenna system, have them fix their work. If it does, contact Ranger and get an RMA.
It's also possible you've got two faults: a DOA radio (like a factory refurb that's not tuned to spec), AND a bad antenna system install. You can rule one of them out with a spare radio.
But you've got two variables in your equation right now: new radio AND new antenna system. Solving for X and Y requires being able to eliminate one or the other.
Just a thought -- and since I'm so old, and they occur so seldom, I try to write them down as soon as they flash through my brain, lest they disappear....... dang it, where are my keys? Hey, you kids! Get off'a my lawn!
73,
Handlebar

 

What kind of antenna? Sounds like a antenna ground issue.

 

If you're picking up the truck through your radio, it is a grounding issue. Where are you getting your power source for your radio?

 

Try running it directly to battery. If that doesn't work, they do make filters to cut out the truck noise.

 

Having a meter show essentially zero reflected voltage doesn't necessarily mean the antenna is resonant on the frequency you need it on, or that it's an efficient radiator. I can pick the right length of coax and either short it or leave it open and have it show a 1:1 SWR at the other end if I know what frequency you're going to operate on. It's unlikely to happen randomly, and there's no reason to do it on purpose, but it illustrates that good SWR does not always mean good antenna. You *could* have a 50 ohm dummy load at the end of any length of 50 ohm coax and show a 1:1 SWR, yet not have it radiate (or receive) more than 100 feet or so.

As for your antenna itself, the thickness of the whip doesn't matter much. It affects bandwidth, but if it's tuned to resonance, the thickness won't matter. On the other hand, all other things being equal, remember that a full sized antenna for CB is ~102-108 inches long, depending upon where in the band you operate. (Over a great ground, my 102" actually resonates at 28.980 MHz, but the SWR is less than 2:1 on CB channel 1, so I'm OK with, cuz I use it for ham and CB. I put a potbelly spring on it if I *need* it centered in the CB range.)

So not everyone has the room for 8-1/2 feet sticking up above their vehicle, and it's common to shorten them by compensating for part of the physical length with a loading coil. But the catch is that most coils don't radiate, leaving only the whip (the straight section) to work as the actual antenna. The coil is necessary to raise the feedpoint resistance to closer to the 50 ohms that the radio expects to see at the end of the coax.

The placement of the coil is important, too. On a quarter wave antenna (and we're going to treat the 102" and the shortened ones as quarter wave antennas for this), the feedpoint (where your coax attaches) has a specific relationship between voltage and current. It turns out that the current is at a maximum, and the voltage is at a null (zero). The values change (easier to see on a graph), and at the very tip of the whip, the voltage is at its maximum, and the current is at zero.

This is important cuz maximum radiation from a radiator (antenna) occurs where the current is at a maximum. So on a quarter wave mobile, that means the greatest radiation is likely to be at the base. But when a shortened antenna has its coil at the base, that maximum current happens at a part of the antenna (the coil) that doesn't radiate. By the time the signal "gets out" of the coil towards the tip, the current is dipping, and the voltage is rising.

Top loaded antennas, typically seen on fiberglass ones for CB, get to radiate lots of signal at their base because the wire wrap near the base is usually straight, or nearly so. By putting the loading coil at the top, it's way up where the current approaches zero value, so there's essentially nothing lost by having it there. A disadvantage to fiberglass antennas is that they're usually more fragile than stainless ones, but stainless ones are harder to load at the top without having them fold over double when you start moving.

Which is what gives rise to a lot of the center loaded stainless antennas you see on vehicles. They enjoy the durability of a stainless whip at the top, and the bottom (below the coil) is also plain steel (or plated, but at least it's not a coil). Somewhere a couple of feet up is the loading coil, and if the overall length is 5 or 6 feet, it takes very little "coil value" to make up for the missing physical length (remember, a full size antenna would be ~8-1/2 ft).

There is an exception to the "coil-not-radiating" part, but that's only when the coil is wound as a helix, which is a special relationship between its length compared to its diameter. It's commonly used in fiberglass antennas, and in the "rubber duckie" antennas you see on ham and public safety handhelds, where a 3" or 6" rubberized antenna is doing a poor (but sometimes acceptable) job to substitute for an antenna that would otherwise be 19" long, and too long to wear and hold easily.

With any shortened antenna, as long as all the other radios you need to talk to are always close enough to compensate for the reduced efficiency of your compromised antenna, it can be acceptable. In public safety and ham systems, it's common to use a repeater on a tower or mountaintop to extend the range of individual radios, but that's not an option in Citizens Band.

So you're back to using an antenna that has as much physical length as you can fit, without taking out itself or drive-through lights, or grinding off the tip on repeated overpass strikes.
The other part of the antenna equation is that the outer part of the coax -- the braid -- is connected to the bracket of the antenna, which ideally is connected to a substantial flat area of metal that's perpendicular to the antenna (like a typical roof of a vehicle, if only they were still made of metal...). That surface provides the return path for the electromagnetic field that's radiated by the whip of the antenna. It's typically referred to as the "ground plane" because it seems to make sense, even though technically the ground plane is the actual ground over which we drive. The metallic shell of the vehicle to which the coax braid is connected is supposed to help make the whole vehicle work as a capacitor to couple to the actual ground plane, to increase the radiation efficiency of the whole system. (This whole thing works in reverse for receiving, too.)

If you don't have sufficient metal on/in/near your antenna mount, sometimes you can fool your SWR meter by adding in enough "reactance", meaning either values that act like capacitors or coils, by changing the length of the whip, or changing the spacing between the mount/whip and the body, or other physical changes that may or may not actually increase your radiated signal's efficiency.

As for your noise, try a couple of things. Run the power straight from the battery (and ground, too, unless you've got a solid ground bus under the dash). Turn it on without the engine or any accessories running, note the noise level. Start adding accessories; you'll note that electric motors (wipers, windows, fans) will make a characteristic buzz. As you identify individual noise sources, unplug the antenna cable from the back of the radio and see if the noises diminish. If they do, you'll have to suppress the noises at their source. If they don't, you may be able to kill them off with a DC line filter for the radio's operating current. It may take a combination of source suppression and DC line filtering.
Finally, start the engine. Even with a diesel, there are still lots of electrical noise generators: injectors, alternators, engine cooling fans -- Sources, thy names are Legion.
The ANL and Noise Blanker on the radio are designed to take care of two different classes of noises. They're not perfect, but they might help, and at least let you decide which noise sources need further attention and which ones can be adequately tamed by the radio itself.

<whew!> I think my fingers are smoking.
That should at least give you something to start with. This stuff is a distillation of the easy things I've learned from 50 years of being licensed in one radio discipline or another for 50 years as of this past March.
Geez, I'm getting old....

Anyway, hope it helps. If you've still got questions, fire away.
73,
Handlebar