Mobile radio issues

[Tbolvin78]

Why would I have better reception with my vehicle turned off, today I was at the store and I was talking with my daughter at home and there was a good amount of static and as soon as I turned my Jeep off I could hear her crystal clear. My question is what would cause this to happen?

 

 

 

 

[kidphc]

Rfi, or installation issue from the electronics running on the car.

Seems like the shielding is kinda crappy on alot of Chrysler products. Turn off the car and rfi is gone. Some times the delayed accesories can still introduce noise till about 5minutes after shut off.

Your coax can act as a big antenna, routing can make a difference. Generally, a good practice in mobile installs is to keep the coax ad far away from power and canbus lines as possible. Cross those lines if possible at 90 degrees with the coax.



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[WRUU653]

29 minutes ago, kidphc said:

Cross those lines if possible at 90 degrees with the coax.

This ^^^ 

[axorlov]

RFI can also come from power wires. This is why I like to run both (+) and (-) directly to the battery, both fused, generous gauge. Even though it is not recommended way to power radio on modern cars.

[nokones]

Motorola installation instructions for mobile environments state ground the controlhead and radio ground wires to chassis ground and not at the battery for better performance and the appropriate power wires to the battery, of course with the exception of the ignition sense yellow wire unless, you want constant power bypassing the ignition switch sensing.

[WRQC527]

3 hours ago, Tbolvin78 said:

Why would I have better reception with my vehicle turned off, today I was at the store and I was talking with my daughter at home and there was a good amount of static and as soon as I turned my Jeep off I could hear her crystal clear. My question is what would cause this to happen?

 

 

 

 

What radio are you using? What is your antenna setup? How is your radio connected to the power source? Does the static get worse when you are moving? What model / year of Jeep? There are a lot of variables and causes for what you are describing. The more information you provide, the more we can help.

[wayoverthere]

I'd also be curious about antenna location, and what might be close by.

I get a ton of RFI from some Amazon special LED headlight bulbs, to the point of 2m being near unusable. It wasn't an issue previously, with the antenna on the roof, but once I moved the antenna to the front fender, major RFI.

I've read of using copper scouring pads to shield noisy LED/HID ballasts, but keep forgetting to track some down to test with.

[kidphc]

I'd also be curious about antenna location, and what might be close by.
I get a ton of RFI from some Amazon special LED headlight bulbs, to the point of 2m being near unusable. It wasn't an issue previously, with the antenna on the roof, but once I moved the antenna to the front fender, major RFI.
I've read of using copper scouring pads to shield noisy LED/HID ballasts, but keep forgetting to track some down to test with.

I had a fender mount that was introducing a lot of rfi in the middle of the gmrs band. 2m/70cm cap modded radio.

Installed a dedicated gmrs radio and antenna (back 1/3rd of roof). Noise was manageable with just a hair of squelch.

Turns out the rfi noise was caused by a failing brake accumulator, and hydraulic leak into the abs computer. My generation landcruiser and some 4runners use a electric motor to build brake pedal pressure. God awful expensive part. The rfi went away when the brake module was replaced.

When I find leds that make rfi noise that is noticeable, in the trash it goes. It's the driver, lots of leds you can't replace the driver.

A neighbor of mine has decent inverters on his solar panels. Only really made noise when at peek power, sunlight going full tilt on the panels. My noise floor goes from s3 to almost s6-s8, usually not home at those times. His plasma screen was terrible also, thank God he upgrade the tv. A lot of rfi comes from cheap electronics and poor shielding, sigh.

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[Sshannon]

12 hours ago, Tbolvin78 said:

Why would I have better reception with my vehicle turned off, today I was at the store and I was talking with my daughter at home and there was a good amount of static and as soon as I turned my Jeep off I could hear her crystal clear. My question is what would cause this to happen?

 

 

 

 

RFI coming from the vehicle electronics or charging system.  

[Tbolvin78]

11 hours ago, WRQC527 said:

What radio are you using? What is your antenna setup? How is your radio connected to the power source? Does the static get worse when you are moving? What model / year of Jeep? There are a lot of variables and causes for what you are describing. The more information you provide, the more we can help.

The radio I am using is radiodiddy DB25-G, the antenna I am using is Midland ghost and the coax is rg58u. The antenna is mounted on the driver side with a hood mount on a 2010 Jeep wrangler. The radio is connected to the battery + and the - is connected to chassis ground. The only time it’s real bad is when I have my headlights on and when I turn my fog light on the radio goes completely out, that is definitely caused by my cheap LED lights from Amazon 

[Tbolvin78]

11 hours ago, WRQC527 said:

What radio are you using? What is your antenna setup? How is your radio connected to the power source? Does the static get worse when you are moving? What model / year of Jeep? There are a lot of variables and causes for what you are describing. The more information you provide, the more we can help.

I also plan on getting ferret clamps for my headlights and fog lights to see if that helps any.

[Over2U]

A classic source of radio frequency interference (RFI) used to be from the engine ignition system (spark plugs and their wires, etc.).

[WRWR489]

As a certified master technician, I would go with alternator whine, diodes failing. Most ignition systems are coil on plug now a days, the high voltage is sent through a big Faraday cage called the cylinder head. Lose one out of six rectifier diodes in the alternator, you can see the frequency change on a analyzer, lose 3 you can hear the whine with your ears.

[WRWR489]

Your cheap LED's are not helping. Maybe a big ground strap from your mount to the main body would help?

[wayoverthere]

1 hour ago, WRWR489 said:

As a certified master technician, I would go with alternator whine, diodes failing. Most ignition systems are coil on plug now a days, the high voltage is sent through a big Faraday cage called the cylinder head. Lose one out of six rectifier diodes in the alternator, you can see the frequency change on a analyzer, lose 3 you can hear the whine with your ears.

On this line of thinking, wouldn't alternator whine show up as varying with engine speed?

On my cheap LED issue, I have some copper mesh en route that I'm going to see if it helps my RFI issue.

[WRWR489]

You are correct. the frequencies would go up with engine RPM, I was responding to the ignition noise. Get the ground wire as short as possible to the chassis of your mount for the radio, run power from the + of the battery and ground your hood to the chassis. 

[WRWR489]

I know this has nothing to do with radio, BUT I just sent a 08 Expedition home fixed with wierd BCM actions going on. Too many things to list, but checked all the grounds and the were fine. That was under no load. Tied the BCM grounds together to a new ground and everything worked. Bad ground even though it was not detecable with my equipment.

[WRUU653]

3 hours ago, WRWR489 said:

You are correct. the frequencies would go up with engine RPM, I was responding to the ignition noise. Get the ground wire as short as possible to the chassis of your mount for the radio, run power from the + of the battery and ground your hood to the chassis. 

@WRQC527 posted a DIY filter he made in a similar thread.

 

[wayoverthere]

I forget if the copper mesh idea is something I picked up here or on Reddit, but it's an easy thing to try and I'm sure I can find other uses for the excess mesh too

 

1 hour ago, WRUU653 said:

@WRQC527 posted a DIY filter he made in a s