Can you help me filter my scanner? (Page 1/1)
Kitskaboodle FEB 16, 06:29 PM
Hi all, many moons ago I installed a Bearcat BC350A Scanner in my truck. I rarely use it though but only because I never really got around to addressing its main problem: engine noise/static. It’s almost unbearable to listen to. Well, at least while my engine is running. Anyways, though I’m no expert on engine noise filtering solutions, I know there is some kind of capacitor/ resistor combination that will eliminate most of the noise. Instead of buying some kind of radio noise interference Kit, I was hoping on a DIY approach. I have plenty of caps, resistors, etc in my parts drawers.
Truck is a 94 Toyota Pickup with a 4 cylinder.
What would you suggest? Also, what needs filtering? The positive lead or Ground?
Thanks, Kit

[This message has been edited by Kitskaboodle (edited 02-16-2022).]

maryjane FEB 16, 06:52 PM
"Ignore the static son, just listen to the game
Father to son on a cross Texas trip in 1964 in a 1960 Ford truck with only an AM radio tryin to hear the St Louis game.....
82-T/A [At Work] FEB 16, 07:12 PM

quote
Originally posted by Kitskaboodle:

Hi all, many moons ago I installed a Bearcat BC350A Scanner in my truck. I rarely use it though but only because I never really got around to addressing its main problem: engine noise/static. It’s almost unbearable to listen to. Well, at least while my engine is running. Anyways, though I’m no expert on engine noise filtering solutions, I know there is some kind of capacitor/ resistor combination that will eliminate most of the noise. Instead of buying some kind of radio noise interference Kit, I was hoping on a DIY approach. I have plenty of caps, resistors, etc in my parts drawers.
Truck is a 94 Toyota Pickup with a 4 cylinder.
What would you suggest? Also, what needs filtering? The positive lead or Ground?
Thanks, Kit



It's usually a ground problem. In police vehicles (I only know this because I own a Crown Victoria and used to scavenge parts from them in the junkyard), they have grounding straps on every hinge, body panel, and multiple tying the motor to the frame. This is to reduce interference for their radio / scanners.

But I also know that in most cases, these are wired directly to a separate junction box that also connects directly to the battery. So I think this is what you'd likely need to do... direct positive and negative feeds to the battery. You can still use a relay to control the power ... so, switched power when the ignition is on.
Patrick FEB 16, 07:52 PM

Is there any interference on your radio as well? A few years ago I noticed an increase in a "whine" (went up and down with engine revs) on my Fiero's radio at the same time that the voltmeter started showing a slight decrease in the charging voltage. Turns out that one or two of the three diodes in my alternator had failed. It was a cheap fix.
Kitskaboodle FEB 16, 09:22 PM
Patrick, I should have mentioned that there is no problem with listening to the radio. (No background noise whatsoever) But when I run the scanner it’s a whole different ballgame.
I can check my grounds but I’m not so sure that will solve the issue. Speaking of my stereo, many modern stereos have a built in noise suppression doo-hickey in the wiring harness. It’s been so long I don’t remember if this model of Pioneer has it.
Kit
Patrick FEB 16, 09:37 PM

quote
Originally posted by Kitskaboodle:

Speaking of my stereo, many modern stereos have a built in noise suppression doo-hickey in the wiring harness. It’s been so long I don’t remember if this model of Pioneer has it.



Are you referring to a Clamp?
82-T/A [At Work] FEB 17, 07:39 AM

quote
Originally posted by Patrick:

Are you referring to a Clamp?




Hah, yeah... Ferrite clamps!


Kitskaboodle, I want to make sure I'm not confused. Are you saying that your SCANNER is causing interference, or everything else is causing interference for your scanner?

If the SCANNER is causing interference, then definitely, a ferrite clamp on the power cable and maybe antenna might do the trick. But if everything else is interfering, then I don't know... grounds are supposed to help solve that.
Kitskaboodle FEB 17, 10:52 AM
Engine electronics / noise are causing scanner to have lots of static, putt-putting, etc and it does goes up and down with engine rpm.
Kit
82-T/A [At Work] FEB 17, 11:04 AM

quote
Originally posted by Kitskaboodle:

Engine electronics / noise are causing scanner to have lots of static, putt-putting, etc and it does goes up and down with engine rpm.
Kit




Ok, just wanted to make sure. So then everything-else is causing interference to the scanner.

I think you're only solution is to have a direct connection (negative) to the battery. You should be able to wire this quite easily with some wire going through the hood, in the passenger door, and hook it up that way. Drive around... see if that fixes it. If it does, then you know what you have to do (run an actual wire). Positive should be fine, but the interference is coming through the body / chassis.


Not your car specifically, but here's a write-up for the option code for the "Radio Suppression Package" that was included when a city would order a "Police Package / P71" Crown Victoria:
https://www.pontiacperforma...pression_Straps.html


It goes into detail about the problems you're having right now. So you could ground everything to help reduce interference, but it's probably just easier to wire up the ground / negative directly to the battery. You could put a ferrite bead on the positive line-in, and that will help a little... but the problem is really everything else.