Hi. I’m new here. I bought a Chrome Cobra 29 LTD recently. I put it in my 04 Expedition. There is constant static coming from the CB. Even with the car off, and the antenna disconnected. When I switch the S/RF, SWR, CAL lever to CALIBRATE my antenna, the static is still there. Shouldn’t the static noise go silent when I put the switch on CAL without keying the mike? The SWR meter seems to be working and my antenna warning light isn’t coming on. The electric interference from my alternator is terrible with the Expedition running. I have read that I need to run my power and ground wires directly to the battery. I did that, and it doesn’t help. How would it help when the positive charge wire is running directly to the battery from the alternator?
I don’t have any interference from the interior switches. I even tried running a separate ground wire from the CB case to the chassis. I have noticed that the ALT interference goes away when the coax cable is disconnected. Any constructive criticism or help is appreciated. Thanks guys/gals.
Lets start with the basics. Ideally, you want the positive leads to come directly off the battery and the negative lead to go to a chassis ground point.
As far as the noise goes, have you touched the ANL, NB, SQL, and RF Gain settings?
I haven’t done anything to the inside of the radio. I don’t understand how the electronics work in them, so I don’t mess around inside them.
According tho the SWR meter the antenna is calibrated fine. No red warning light. And the SWR reading is at 1. I bought it back in November. It is a professional refurbished unit from Cobra. I will move the ground wire to chassis, and see if that helps with all the alternator noise.
Just changing the ground point won’t do muck for noise, but see for yourself. Those ANL,Nb,and RF gain controls are not inside the radio, they are typically on the front panel. Just from what you’ve said I would definitely read the manual! Twice!
You mean the round knob looking deals on the front of the cb that turn right and left? Or are you referring to the little switch deals that go up and down? What about the knob on the right that goes from 1 to 40?
When zapp25 replied earlier and asked the question about the ANL, NB, SQL and RF settings, I thought he was referring to me taking the covers off the unit and getting screwdriver happy on the circuit panel.
I misunderstood that question. But I’ll go ahead and re read the owners manual “twice” and see if anything jumps out at me.
… I think I’m being ‘had’. That’s all folks…
Nope, the knobs and switches on the front of the radio. Squelch and RF Gain are the most important. One will cut out the noise by limiting the minimum signal level needed to open squelch (it’s like a, RF must be at least this strong before I’ll reproduce it setting). The RF gain is adjusts the sensitivity of the signal. Essentially, you want it to be high enough to amplify weak signals but low enough that it isn’t amplifying the noise.
A basic radio setup:
- With the engine off, squelch turn squelch and RF Gain all the way counter clockwise. Noise Blanker and ANL should be off. Tune to a unused channel.
- While watching the signal strength meter, begin to turn your RF Gain clockwise until the needle just begins to move (that’s the point which you are amplifying the noise) and back it off just a smidge.
- Turn the squelch clockwise until the noise coming out of the radio cuts out. Then continue to turn it just a smidge more (1/8th turn or less).
- (Gentlemen) Start your Engine(s).
- If the noise comes back, toggle the noise blanker and ANL back on and see if it goes away. If not, readjust your squelch with the engine running.
Your antenna is mounted appropriately, and your CB radio is mounted in the dashboard. You believe your radio is ready to operate because everything is linked, right? Unfortunately, you might not be happy with the outcomes. So, before utilizing the CB radio, the CB antenna must be calibrated.
Calibrated? We have somebody with a CB, and antenna and his vehicle. In his first post he says that with the car off (I assume he means ignition off) he still gets interference. First thing to check is the level of this interference in relation to the squelch. When the squelch is open, can you hear the interference? I assume yes. Can you silence it when you rotate the squelch? Next test - disconnect the antenna. If you open the squelch, you hear the hiss? Turn up the squelch till the radio goes silent. Then connect the antenna again. Does the interference suddenly burst back again.
One of two things is happening. The antenna is capturing local interference and the radio lets you hear it - OR - the interference is being produced (as in a fault) inside the radio. If this is the case - removing the antenna won’t do much.
If we assume the interference is being captured by the antenna and is local, is it on every channel? If it is - it is Wideband interference. It could be generated by something in the vehicle. I had a sat nav once that created so much noise that while VHF and UHF radios were fine, 27 and 28MHz were unusable.
This is a really good case where a quick YouTube video would really help so we can see what you are doing, what the knobs are actually adjusting and what the interference sounds like. It’s so difficult to know if one persons interference is actually just empty band noise, or real interference. People often don’t have the correct technical vocabulary. Noise, hiss, hum, interference, distortion all mean different things to some people.
Connecting the red and black cables to the battery, cut out your vehicles regulators, isolators and other cleverness - the most direct and simple solution to power. Often, a local 12V point like a cigarette lighter socket and a screw into the metal chassis or bracketry will work just as well. With many vehicles now having umpteen computers all over the place - they can be very noisy, but a characteristic noise we might notice if we hear it. Up till then, we are guessing about your noise?
Static is normal until you turn the squelch, which at a certain
level will eliminate the noise.
DO NOT connect the black wire directly to the battery! Connect it to a suitable ground point away from the battery. Most modern vehicles have a power management system and connecting anything to the negative battery post could mess this up.
You know I did not know that!