Need advice on wire gauge.

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Joined: Wednesday 5th Dec 2007, 9:29
Location: Gilroy,CA

Need advice on wire gauge.

Post by PWA757 » Wednesday 5th Dec 2007, 9:39

I gonna install a uniden pc 122 in my pickup. I'm thinking of running the power cable straight to the battery. What is the minimum wire gauge and fuse should I use or where can I find the info. This unit has 30 watts. I tried run it to the fuse box and got alot of engine noise.
Thank you.

US Army Retired.

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Post by RedEye » Wednesday 5th Dec 2007, 13:56

You may still get engine noise even if you go straight to the batt....

What type of noise? a pop,pop,pop indicates a bad plug wire, and a whining noise that goes up and down with the engine is from the alternator, usually from a leaking diode in the alternator that is passing AC current. You could also just have a bad ground to the radio but more likely the alt. Check the ground first.

Here's and old mechanics test, with the engine turned off, and key in off position, take a metal screwdriver and place it against the bearing housing on the back of the alternator. If it has a magnectic pull, (attracts the screwdriver) then it most likely has a zenor diode leaking allowing the coil to stay charged, hense creating the magnetic fileld. It will be very weak, but it will pull the screwdriver slightly. Of course from here you would do an amp draw test, but thats another forum!!!
If the alt is in a safe place to try this when it is running, then you will notice a strong magnetic pull as the alternator creates AC voltage and converts to DC voltage

You will probably need a noise filter to eliminate that problem, available at most electronic stores.

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