for EMS/fire ops

whenever the engine is running i get this low-pitched hum/buzz constantly over the built-in speaker, ppl say that the buzz is not on my transmissions

alternator? or what?


and if i put like a high-pass filter inline w/ the power will that get rid of it?

power is straight wired to the battery (w/ fuses inline).

6/7/2008 10:45:25 AM

sounds like alternator noise

you can install a ground loop isolator.

6/7/2008 11:02:23 AM

usually its ignition coils that make the noises

6/7/2008 11:10:48 AM

the only way it is alternator is if it varies with engine speed

regardless a ground loop isolator will fix it at the expense of input line voltage

6/7/2008 11:46:06 AM

Quote :

"the only way it is alternator is if it varies with engine speed"

evan does the pitch of the buzzing change as you rev up the engine?

in my limited auto experience, ive never heard of it where it was a constant buzz, always the alternator.

6/7/2008 11:48:55 AM

i had a constant buzz when the car was in accessory mode

a clean ground didnt solve the problem

6/7/2008 12:27:54 PM

Quote :

"ground loop isolator."

Quote :

"usually its ignition coils that make the noises"

nah its usually the alternator

[Edited on June 7, 2008 at 1:51 PM. Reason : asdf]

6/7/2008 1:51:02 PM

is this a chevy

6/8/2008 2:37:12 AM

^ pacifica

6/8/2008 10:18:30 AM

it's alternator whine. try a different ground. make sure you have direct metal contact. i can't believe you are getting alternator whine from a scanner. btw, what kind did you go with?

6/8/2008 3:12:50 PM

its not a scanner, its a transceiver.

doesn't exactly sound like a ground loop to me although i'll go pick up an isolator and try it out

i tried different grounds, even tried directly to the neg battery terminal and it was the same everywhere.

usually i get buzzes and hums like this when i have multiple pieces of equipment (say, the head unit and the car pc in the back) connected together but on different ground points, as the different points have different electrical properties even though they're technically the same ground.

that's what was confusing me, as this is totally isolated

6/10/2008 8:36:24 AM

that sounds like its not an ideal ground conductor then, some sort of impedance restricting ground current and inducing a voltage and backfeeding into your equipment.

6/11/2008 6:53:00 PM