Hey guys. Just wanted to throw this out there and get some ideas on how to reduce or eliminate Electrical System Whine and Noise on a vehicle Installation. The vehicle is a 2006 E-450 Turbo Diesel and the radio is a CDM 1250 UHF Hi. Noise is heard on the transmit of the radio by other users listening. Any ideas on how to eliminate this problem. Thanks
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Removing Electrical System Whine/Noise on Vehicle Installation
- Thread starter fdnyradio
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If you are being told that there is a high-pitched whine or squeal on your radio transmissions, and it varies in pitch if you accelerate the engine... you have alternator whine. The most effective fix is a filter placed in the 12VDC power line to the radio consisting of both an inductor (coil) and capacitor. Search on the keywords "alternator whine filter" and you will find filters you can buy off the shelf for this problem. The best way is to roll your own using the instructions in this article:
http://www.worldwidedx.com/home-brew/31492-building-simple-alternator-whine-ignition-filter.html
If you are being told that there is a high-pitched whine or squeal on your radio transmissions, and it varies in pitch if you accelerate the engine... you have alternator whine. The most effective fix is a filter placed in the 12VDC power line to the radio consisting of both an inductor (coil) and capacitor. Search on the keywords "alternator whine filter" and you will find filters you can buy off the shelf for this problem. The best way is to roll your own using the instructions in this article:
http://www.worldwidedx.com/home-brew/31492-building-simple-alternator-whine-ignition-filter.html
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mmckenna
I ♥ Ø
Where is the radio power feed connected?
I've had alternator whine issues and been able to fix them by changing the grounding point. Cheaper than a filter.
I've had alternator whine issues and been able to fix them by changing the grounding point. Cheaper than a filter.
kf5qgf
Member
I like that info, but i'm getting whine on a scanner that's independently (self contained batteries) powered, how would I install for this?
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The filter shown obviously only works with radios that are connected to the 12VDC power of the vehicle, and the alternator whine is coming in via the DC power connection. In the case of a handheld scanner the noise you hear is being radiated by RF or EMI directly into your handheld. You'll need to first ensure it is coming from the alternator or some other source. Then you might try using the handheld as a near-field "sniffer". Remove the antenna from the handheld and see if the noise is reduced or gone. Start the vehicle and sweep it with the scanner until you find the spot where the noise is loudest. If your scanner has an attenuator you may need to use it to reduce the noise while sweeping for the source. Start under the hood, but the are also components in the dash that can cause interference. Famous for this are cell phone chargers that plug into the cigarette lighter socket. People have also reported RF noise from digital clocks and GPS units.
The filter shown obviously only works with radios that are connected to the 12VDC power of the vehicle, and the alternator whine is coming in via the DC power connection. In the case of a handheld scanner the noise you hear is being radiated by RF or EMI directly into your handheld. You'll need to first ensure it is coming from the alternator or some other source. Then you might try using the handheld as a near-field "sniffer". Remove the antenna from the handheld and see if the noise is reduced or gone. Start the vehicle and sweep it with the scanner until you find the spot where the noise is loudest. If your scanner has an attenuator you may need to use it to reduce the noise while sweeping for the source. Start under the hood, but the are also components in the dash that can cause interference. Famous for this are cell phone chargers that plug into the cigarette lighter socket. People have also reported RF noise from digital clocks and GPS units.
Power your 2-way from the recommended power tap under the hood, not directly from the battery post. Disconnect and clean the battery posts and clamps on both positive and negative and then coat them a conductive grease before reassembling them. An old tooth brush and baking soda paste works great for cleaning battery posts. If this doesn't fix your problem then you most likely have a ground loop where part of the current from the alternator is being conducted by the radio's power leads or antenna braid. Try to connect the radio's ground (black wire) to the same point where the battery's ground connects.
Under most conditions, the battery will supply enough filtering to eliminate any alternator wine so you don't need an external wine filter. Another problem is having an alternator that isn't big enough to supply the needed current. This will mean that both the battery and the alternator are supplying the current and will greatly reduce any filtering from the battery. This can be caused by an alternator that is sized too small for the load or by defective diode(s) in the alternator. The alternator's current rating should be okay unless you have replaced it with an after-market unit. The alternator should be able to supply the entire electrical load at idle, including the head lights but not including anything you have added.
Good luck.
Under most conditions, the battery will supply enough filtering to eliminate any alternator wine so you don't need an external wine filter. Another problem is having an alternator that isn't big enough to supply the needed current. This will mean that both the battery and the alternator are supplying the current and will greatly reduce any filtering from the battery. This can be caused by an alternator that is sized too small for the load or by defective diode(s) in the alternator. The alternator's current rating should be okay unless you have replaced it with an after-market unit. The alternator should be able to supply the entire electrical load at idle, including the head lights but not including anything you have added.
Good luck.
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