Audio unit and road noise

[Camohurley]

Ok guys I'm new to the forum and I might post this in the wrong place if so I'm sorry! But I've got a 77 Chevy Scottsdale that was used as a brush truck by my fire department. I've been trying to restore her to a somewhat new condition. The issue I'm having is alot of road noise in the radio. It's got the stock am radio in the dash with an fm box under the steering collum. The antenna wire goes from windshield to fm then the fm box has a antenna wire that goes to the am radio.when the radio is on you can hear all electrical headlights coming on the blinkers blinking even the buzz when you first turn on the key comes thru my speaker. I've tried replacing the antenna rerouting the antenna wire rewireing the radio itself and trying a known good am only radio all of with still has the same issue ( I've tried plugging the antenna straight into the AM radio and it still does it so I've rulled out it coming from the fm box) someone please help!

 

[Honky Kong jr]

Ok guys I'm new to the forum and I might post this in the wrong place if so I'm sorry! But I've got a 77 Chevy Scottsdale that was used as a brush truck by my fire department. I've been trying to restore her to a somewhat new condition. The issue I'm having is alot of road noise in the radio. It's got the stock am radio in the dash with an fm box under the steering collum. The antenna wire goes from windshield to fm then the fm box has a antenna wire that goes to the am radio.when the radio is on you can hear all electrical headlights coming on the blinkers blinking even the buzz when you first turn on the key comes thru my speaker. I've tried replacing the antenna rerouting the antenna wire rewireing the radio itself and trying a known good am only radio all of with still has the same issue ( I've tried plugging the antenna straight into the AM radio and it still does it so I've rulled out it coming from the fm box) someone please help!

You will need a noise filter on the antenna that should take care of it. You could have a damaged antenna cable that the shielded casing isn't doing its job. Welcome to the site.

 

[Camohurley]

Thanks for the welcome! Also I tried an inline antenna supressor and it made it where I couldn't hear the music coming thru at all!

 

[Camohurley]

You will need a noise filter on the antenna that should take care of it. You could have a damaged antenna cable that the shielded casing isn't doing its job. Welcome to the site.

Also I just tried running a hot wire straight to my battery with the new antenna and there was way less road noise...is there a way to rewire the radio to a ignition with a fuse but bypass the main fuse box where it seems the interference comes from

 

[Honky Kong jr]

Also I just tried running a hot wire straight to my battery with the new antenna and there was way less road noise...is there a way to rewire the radio to a ignition with a fuse but bypass the main fuse box where it seems the interference comes from

You can put a noise filter on the 12v supply wire feeding your radio.

 

[Camohurley]

You can put a noise filter on the 12v supply wire feeding your radio.

Thanks just ordered one I'll update Saturday

 

[Honky Kong jr]

Thanks just ordered one I'll update Saturday

 

[1987 GMC Jimmy]

Good suggestion here. I don't know if you're going for a strict OEM resto, but since it's a '77, I'd upgrade it to a Delco 2700 AM/FM/Cassette or just AM/FM if you don't use the deck for MP3 tunes. Much better looking and more versatile than the AM unit, and if yours has the '77-'9? radio harness, which I don't see why it wouldn't, it should be plug and play while cleaning up the excess to make it tune FM. Just food for thought there.

 

[Camohurley]

Good suggestion here. I don't know if you're going for a strict OEM resto, but since it's a '77, I'd upgrade it to a Delco 2700 AM/FM/Cassette or just AM/FM if you don't use the deck for MP3 tunes. Much better looking and more versatile than the AM unit, and if yours has the '77-'9? radio harness, which I don't see why it wouldn't, it should be plug and play while cleaning up the excess to make it tune FM. Just food for thought there.

I've put some thought into that but it's kind of a personal thing to me to keep it the way it was when the fire department had it in honor of my friend a fellow firefighter and. U.S marine who passed away in 2015. So I'm trying everything I can to keep it original! Thanks for the reply though I greatly appreciate everyone's input!

 

[theblindchicken]

Would love to see a build thread of the truck and all the restoration you've gone through it is.


If the noise filter doesn't help on the 12v, i'd check to see if a shared ground is also causing the issue?

 

[Camohurley]

Would love to see a build thread of the truck and all the restoration you've gone through it is.


If the noise filter doesn't help on the 12v, i'd check to see if a shared ground is also causing the issue?

Definitely! I appreciate the advice it's a slow project and we're gonna keep the fire engine red color and some of the dents and scratches as far as interior I wanna get the seat repaired but keep the dash pad (has a few cracks but has the unit number and some original writing since it was on the department) my big thing is I wanna have the bed repaired due to some big rust spots so I'm thinking reinforce it with a steel plate and bedline it. I also one day wanna have a engine with the chrome and all that and make it a show truck even though on the outside it still has it's appearance of it's service days

 

[1987 GMC Jimmy]

I've put some thought into that but it's kind of a personal thing to me to keep it the way it was when the fire department had it in honor of my friend a fellow firefighter and. U.S marine who passed away in 2015. So I'm trying everything I can to keep it original! Thanks for the reply though I greatly appreciate everyone's input!

I totally understand! I hope you get the sound cleaned up on it!

 

[Camohurley]

Ok guys quick update. Just installed the 12v noise supressor so now it's got that the antenna noise supressor a new antenna and a new speaker but I'm still getting major electrical noise. Anytime a light comes on (blinkers or pressing the brakes or turning the headlights on and off) and on acceleration I'm completely stumped at this point the only thing I can think of is I'm getting major interference from my fuse box.

 

[Honky Kong jr]

Ok guys quick update. Just installed the 12v noise supressor so now it's got that the antenna noise supressor a new antenna and a new speaker but I'm still getting major electrical noise. Anytime a light comes on (blinkers or pressing the brakes or turning the headlights on and off) and on acceleration I'm completely stumped at this point the only thing I can think of is I'm getting major interference from my fuse box.

Run a relay for radio power directly from the battery. Use the original radio power wire to trigger the relay.

 

[Camohurley]

Run a relay for radio power directly from the battery. Use the original radio power wire to trigger the relay.

Ok so your saying I should get a relay and wire it to my battery and to the radio and then run the original power wire from my radio unit to the relay to engage the relay correct?