Batboard

I just recently installed a brand new vhf radio system in a 2006 Crestline Ambulance and the whining noise when the truck is idle or moving is so bad you can not hear anyone talk, once you turn the truck off it stops. I have placed a filter in and does not seem to correct the problem, any else that ran across this problems and any ideas how to fix it.

Alternator whine.

If it were a Ford Crown Vic, I'd tell you to get the filter Ford made for that purpose.. but maybe since you are filter savvy you can in-line a filter at the alternator.

I always heard alternator whine was an forewarning the alternator is going to go out too. (but it's an '06 so..?)

You didn't indicate if the whine is a constant pitch or changes with motor speed. Does it change with electrical load? If the pitch stays constant, you may have a fuel pump issue. If the pitch changes with the engine, you have an alternator source issue.

You can try and look at the output of the alternator with an AC volmeter set to the lowest scale. You should see almost nothing for a reading down into the milivolt range. If you see anything above a few milivolst of AC, I would start looking at the alternator.

One other area that you should check out before getting too wound up in this is the battery connections. I have seen brand new autos show up and have a problem like your talking about. It was caused by poor and dirty connections at the battery posts. Couldn't understand how the engine even started. But cleaning the battery post and cable connections solved the whine problem.

Again there are some radios that have poor filtering on the receiver 12 volt input. The audio output stage in the radio was done by a poor engineer. It produces all sorts of while in the speaker when your trying to listen to a transmission. Only a good 12 volt line filter, right at the radio solves this problem.

You might try a test and run the receiver 12 volt feed off of a bench supply in the vehicle and see if your whine goes away. If so, you at least know where to put your efforts.

Jim

Pozy wrote:I just recently installed a brand new vhf radio system in a 2006 Crestline Ambulance and the whining noise when the truck is idle or moving is so bad you can not hear anyone talk, once you turn the truck off it stops. I have placed a filter in and does not seem to correct the problem, any else that ran across this problems and any ideas how to fix it.

The sound does change when the truck is given gas to go. It goes up to a high pitch sound...

So now that you have told us the pitch of the whine changes with engine speed, look at the issues that come from the alternator and battery connections. Measure the AC ripple on the DC voltage and clean the battery connections.

What kind and model of radio are you getting this noise on? Some radios are more prone to this than others.

Jim

Pozy wrote:The sound does change when the truck is given gas to go. It goes up to a high pitch sound...

as i have said in many a post, in other threads about this...

LOOK AT THE FUEL PUMP!

also, might sound stupid, but double check the ground(ing) of the 120AC inverter(if so equipped), I've had the built in cooling fans cause issues before......(not MY install, cleaning up after someone else)

Is it a ford or chevy.

Well there is a 90% chance it is a Ford Powerstroke, in which case, besides the obvious (alternator) there is another cause that can do it...the high voltage used to fire the HEUI injectors can get into the reciever as well. So you need to determine if it is coming in on the antenna or power wires by disconnecting the antenna wire....

Birken

If it is a Powerjoke and a Waris series radio involved, install a good noise filter and a BIG (motor start type) capacitor. Have seen this many times. Problem will go Bye bye.

Powerjokes are famous for fuel pump noise as was earlier stated.

it's not only the powerjokes...it's a recurrent problem that we've seen in many a different ford lines...not only the powerjokes. I've seen gassers do it too.