radio reception affected by parking lights

Hemi Hunter · 10-21-2004, 08:40 AM

Hey guys, I was just wondering if anyone else has had this problem. The fm radio reception gets better with the parking lights on. It's like flipping a switch between some static (lights on) and alot of static (lights off). I've tried different stations and it happens across the band with stations that are fairly difficult to get to begin with. BTW I have the auto headlights and RF stereo.

Zardoz · 10-21-2004, 08:41 AM

I have the RF stereo but don't have the auto headlights and I don't hear anything
with the parking lights on.

Zardoz

bestatchess · 10-21-2004, 10:04 AM

I will check this out when I get mine reassembled. I found this at www.deja.com:

"I have a 92 Chevy pickup which is having radio problems.
Has anyone experienced this or have any ideas on what
my problem might be?

Original AM/FM radio. Problem: Static on AM. To get

rid of static I can just barely turn on my headlights or
parking lights. Static goes away. I've tried other things
like turning on dome light or pushing in lighter but makes no
difference. Static goes away as soon as switch is slightly
pressed. Static will come back eventually, but goes away
when switch is pressed again.

I've seen this problem in the technical notes but have never
read how to fix it.

All help and ideas appreciated.
Mike"

That was the only post in the thread.

pagerdaddy · 10-21-2004, 10:17 AM

It's funny how these radio problems seem to hint at some sort
of grounding problem.

I had a Mustang that had just had the engine removed and replaced,
and seemed to be overheating. The temp gauge would peg over to
high, but the engine didn't even seem hot. This drove me nuts for a
while, and I didn't figure it out until I pulled into a neighbor's driveway,
and when I pulled up on the emergency brake, the temperature gauge
started climbing rapidly!

They had left a ground strap off of the engine when it was put back in,
and when I fixed that, my "overheating" problem went away.

I know one of the members cleaned and sealed the threads on the
antenna, and claimed this improved his reception.

Any thoughts on antenna grounding, or the head unit itself?

Steve

bestatchess · 10-21-2004, 10:38 AM

O.K., here is a SWAG:

Maybe there is a bad ground on the HU. When you turn the lights on, that energizes the illumination circuit for the HU, which gives you a better ground.

titanwild · 10-21-2004, 10:52 AM

Best, You're probably pretty close (bad HU ground) but could also be circulating current in the ground system (aka ground loops). Loops are typical of too many ground paths vs bad or missing grounds. I deal with those issues a lot at work. Surprising how poorly most ground systems are designed.
Dale

bestatchess · 10-21-2004, 11:40 AM

Hey titanwild, I am getting ready to wire new amps & signal path for a stereo upgrade, retaining the RF head unit. After reading about problems others have had with alternator whine believed to be caused by ground loops (with amps grounded at rear of cab & HU grounded directly to battery), I am planning to ground everything to a distribution block on the rear cab wall, to include head unit, pre-amp, LOC, capacitor & amps. Think that will be O.K. or maybe you would recommend something else?

pilot4net · 10-21-2004, 11:58 AM

If it is in fact a "ground loop", wouldn't a ground loop isolator installed on the power supply to the HU or any other radio equipment fix this? It's just a thought!!

pilot4net · 10-21-2004, 11:59 AM

Correction: ...installed on the ground of the HU...

titanwild · 10-22-2004, 03:16 PM

Quote:

Originally Posted by bestatchess

Hey titanwild, I am getting ready to wire new amps & signal path for a stereo upgrade, retaining the RF head unit. After reading about problems others have had with alternator whine believed to be caused by ground loops (with amps grounded at rear of cab & HU grounded directly to battery), I am planning to ground everything to a distribution block on the rear cab wall, to include head unit, pre-amp, LOC, capacitor & amps. Think that will be O.K. or maybe you would recommend something else?

Yep, that sounds good, essentially a secondary/remote single-point ground. Don't know how your'e going to separate the HU ground from the existing system, but going to a common ground for all audio system components has got to help. The secondary SPG should be connected to the primary SPG (battery neg terminal) with a #4 or so. If there's any alternator whine, then start to work with isolation filters in the hot lead to your distribution block. We've fought that problem with mobile ham radio installation for years, and seems that every vehicle behaves a bit differently, in other words, there's some black magic involved! There should be tons of good info on mobile power/ground installations on the ham sites, and a least a couple of books from ARRL address the subject. (I'm sure that with all the automotive high-power audio expertise available, there must be more current knowledge than mine as far as audio installations are concerned.

) Still enjoying the saga of your installation, by the way.