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Author Topic: Please help/suggest with mobile Noise issue  (Read 508 times)
KB3CDF
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Posts: 27


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« on: October 30, 2001, 10:20:17 PM »

Noise appears on both recieve and transmitted signal (2m).  It is a high pitched whine that rises and falls with the rpm of the engine.  Noise disapears when (1.) the engine is off  (2.) alternator acuator is diconnected and the vehicle is powered directly from the battery without recharge.  Noise worsens when headlights on. 'Goes really fowl when headlights, windshield wipers, and defrost are on.

setup:  NMO hole mount antenna, radio powered directly from battery.  Brand New alternator.

Any help or suggestions in testing would be apprieciated.  I though of replacing the battery,  ferrite core around acuator cable on alternator, or perhaps a second deep cell battery with isolator device.

Thanks in advance.

~~
73, John de KB3CDF
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KE4SKY
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« Reply #1 on: October 31, 2001, 08:06:40 AM »

Sounds like a GM vehicle with an in-tank fuel pump?

Go to K2BJ.com and look over the section on locating the sources of noise and fixing.  Mainly oriented to HF mobile, but the solutions work for all.
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WB2WIK
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« Reply #2 on: October 31, 2001, 10:56:14 AM »

Sounds like classic alternator whine.  A brand-new battery with very clean terminals and very low resistance wiring to the rig (not just "direct," but very low resistance -- I always use #8 gauge copper for both + and - leads as a minimum) will usually fix it.  If you have in-line fuses (as you SHOULD), check their holders for oxidation or corrosion, also.  Sometimes a small amount of oxidation on the fuse holder contacts creates all sorts of problems.

Good luck!

73 de Steve WB2WIK/6
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KB3CDF
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« Reply #3 on: October 31, 2001, 01:15:01 PM »

vehicle: '99 Blazer (S10) Chevrolet

Wiring from battery is the largest gauge zip-cord (blk-Red) I could find.  I think it is 8 gauge.

Thanks....  I have been hunting this issue for a little less than a year without success.  It's very frustrating.  
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WB2WIK
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« Reply #4 on: October 31, 2001, 05:52:38 PM »

When all else is exhausted, you could install an alternator filter.  This goes in the charging lead between the alternator and the battery and must handle a lot of current, so it's not a small item.  You might check with your Chevy service center to see what they recommend, or if they stock one (they often do, and will continue your warranty coverage provided they use "their" filter, and install it).

73 & good luck!

Steve WB2WIK/6
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AF4WP
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« Reply #5 on: March 24, 2002, 06:47:24 AM »

Had a similar problem in my Toyota Camry.  When the alternator failed and was replaced, the noise went away.

Good luck,
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