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bmlbytes
02-27-2017, 12:23 PM
So I know this isn't quite ham radio, but I thought I'd post here because it will probably be a similar issue once I get my 70cm/2m radio.

On my CB radio, when I turn on the windshield wipers, the radio thinks it's receiving and it over powers the squelch. When transmitting, there is a bit of alternator whine. Not too bad, but a bit. I'm wondering if there is a good way to prevent this. Right now, the CB's power cables go directly to the battery. They are the cables that came with the radio, and nothing has been spliced in or added to the cables. The antenna ins't the greatest. It's a 4 foot Firestik, but its mounted on a "no ground-plane" mount (http://www.firestik.com/Catalog/NGP_M2.htm). The SWR meter shows about 1.8:1.

I want to try to resolve as much of this as possible before buying an amateur radio for the Jeep. I was thinking that adding a large capacitor to the power lines might help eliminate noise from other electronics, but I have no idea how large of a capacitor I would need.

Any ideas?

redneck20
02-27-2017, 04:02 PM
How is the antenna wire ran , there should be no loops or wrapped around any other wires


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Will E
02-27-2017, 05:08 PM
You won't have the same issue with 70cm/2m, they use FM not AM. I am not sure how to solve your cb issue. There might be a noise filter you can add?

GilaMtnJeep
02-27-2017, 05:35 PM
I had that issue with my CB. Adding a noise filter in the power line did nothing. Found out the noise was caused mainly by the fuel pump. I installed a torroid in the power line close to the pump and it helped some.

bmlbytes
02-28-2017, 10:06 AM
How is the antenna wire ran , there should be no loops or wrapped around any other wires
The antenna cable is not run near any power lines or other wires. The cable is a bit long, so its wrapped around itself behind the CB unit, but not near other wires.


I had that issue with my CB. Adding a noise filter in the power line did nothing. Found out the noise was caused mainly by the fuel pump. I installed a torroid in the power line close to the pump and it helped some.
Do you have a TJ? I've hear that TJ's have very noisy fuel pumps. For me the biggest offenders are the windshield wipers, and the LED pod lights. The pod lights also connect directly to the battery, so that might be part of the issue. I'll look at getting a torroid choke.

redneck20
02-28-2017, 10:13 AM
Unrelated but the wire should not be wrapped around itself either your greatly decreasing the ant by wrapping the wire like that


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bmlbytes
02-28-2017, 10:19 AM
Good to know, any recommendations for how to deal with extra coax cable?

redneck20
02-28-2017, 11:07 AM
Cut it off and put a new end on it, or find a longer route for it


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Will E
02-28-2017, 11:50 AM
Prepare yourself for the 18 foot gang.

Xiled1
02-28-2017, 04:50 PM
Might want to try powering the CB from a stand alone battery and see if the noise remains. That way you can determine if the noise is conducted on the poweline or radiated from the noise source. Try attacking the noise source. Start with confirming they are well grounded. Work from there.

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GilaMtnJeep
02-28-2017, 07:20 PM
The antenna cable is not run near any power lines or other wires. The cable is a bit long, so its wrapped around itself behind the CB unit, but not near other wires.


Do you have a TJ? I've hear that TJ's have very noisy fuel pumps. For me the biggest offenders are the windshield wipers, and the LED pod lights. The pod lights also connect directly to the battery, so that might be part of the issue. I'll look at getting a torroid choke.
Yes, an 03 Sahara. I read a few articles online to try and track down the cause of the noise. First is to determine if it is coming through the power line or externally from the antenna. Mine came from both sources. The fuel pump was the hardest to nail down and the electric fan for the trans cooler was obvious. A torroid (if I have the right term) solved those. It's a metallic donut that I passed the power wires for each through. Bring them through and wrap 3-4 turn around it then continue on to the device.

The other noise source was coming in through the antenna. This is easy to determine. Just disconnect the coax at the base of the antenna and see if the noise goes away. If it does there isn't much you can do about it.

When I ran the coax (I had an 18' cable) I came from the antenna (mounted by the right rear tail light) and ran it under the rollbar padding. Came up the right rear rollbar, across the top center, up the driver's side, then to the CB. Mine is mounted overhead by the rearview so the length was almost perfect with no loops, etc.

I also made a flexible jumper by paralleling two pieces of 10 gauge wire. One end connect to the exhaust pipe at the rear most hanger and the frame close by. It actually helped knock the noise down just a touch.

I still have some but it is no where near as bad as when I first put the CB in.

azgypsy
02-28-2017, 07:34 PM
Check your antenna mt!
It's possable it's not grounded correctly!
Same with the radio ground!

GilaMtnJeep
02-28-2017, 07:42 PM
Check your antenna mt!
It's possable it's not grounded correctly!
Same with the radio ground!
Yes, this too!!

I physically grounded my mount to the body with one of those braided straps and did the same thing for the CB case.

Lunatic_Fridge
02-28-2017, 09:47 PM
I'll put a note on my phone calendar to come back to this friday night/saturday morning and give you a write up on the how to find and resolve noises on rx and noises on tx in mobile installations. It gets a bit much to type on a phone.

Lunatic Fridge

Sent from the FrankenHeep

bmlbytes
03-01-2017, 06:07 AM
Thanks everyone. I'll try a few of these suggestions. Lunatic_Fridge, thank you, I will look for that on Friday.

GilaMtnJeep
03-01-2017, 07:05 AM
I'll put a note on my phone calendar to come back to this friday night/saturday morning and give you a write up on the how to find and resolve noises on rx and noises on tx in mobile installations. It gets a bit much to type on a phone.

Lunatic Fridge

Sent from the FrankenHeep
Is this going to be about what comes through via the antenna? I never could get much help and told there's almost nothing you can do about it.


Also, if you're curious about the torroid, this is what I am talking about.

http://i1075.photobucket.com/albums/w434/FernBchJeep/Mobile%20Uploads/IMG_20170301_080141_zpshiq9wfwe.jpg

Xiled1
03-02-2017, 08:41 AM
For true antenna received noise you have to attack the source. Front end filters are usually bulky and expensive for a CB install.



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calvarez
03-13-2017, 12:28 PM
The most common cause of noise issues is grounding, either on the side causing it or the side receiving it. So always first make sure your radio and antenna both are very well grounded. Then do the same for the suspected source. Also the sources are additive, so if you have X amount of noise from the fuel pump, and Y from the wiper motor, the end result is the addition of both. That may be just enough to push things over the edge. So test with the engine off and wipers on.

A small to medium capacitor between the positive lead and ground on the source and/or receiver will often help with high-pitch noises from things like an alternator or motor. It can't hurt to try.

Oh, and you are using resistor plugs, right?