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Radio Noise Problem

zjohnson

Well-Known Member
In a rush to get my car done last year I think we short cut to much on the wiring end. Original issue:
1. RPM based noise on the intercom.
2. Horrible whine when talking out thru intercom.

What I fixed:
1. Radio and intercom where connected to battery switch. Re-wired directly to battery.
2. Cleaned powder coat off of stud to ensure better ground.
3. Ran antenna wire away from power wires, along with radio-intercom wire.

I have a PCI intercom and an Icom radio. In troubleshooting we found the noise was RPM based and made worse by the parker pumper being flipped on and made even worse by flipping the override fan switch on the oil cooler. Its a VW car. With the engine off, radio worked without issues and flipping on the pumper added noise, flipping on the oil cooler fan made the noise worse.

We think the issue may be from a bad ground in the engine area. Are we missing anything? The wires to the helmets are buried in the dash wiring, could this be the issue?

Thanks
 

pkonopasky

Well-Known Member
In a rush to get my car done last year I think we short cut to much on the wiring end. Original issue:
1. RPM based noise on the intercom.
2. Horrible whine when talking out thru intercom.

What I fixed:
1. Radio and intercom where connected to battery switch. Re-wired directly to battery.
2. Cleaned powder coat off of stud to ensure better ground.
3. Ran antenna wire away from power wires, along with radio-intercom wire.

I have a PCI intercom and an Icom radio. In troubleshooting we found the noise was RPM based and made worse by the parker pumper being flipped on and made even worse by flipping the override fan switch on the oil cooler. Its a VW car. With the engine off, radio worked without issues and flipping on the pumper added noise, flipping on the oil cooler fan made the noise worse.

We think the issue may be from a bad ground in the engine area. Are we missing anything? The wires to the helmets are buried in the dash wiring, could this be the issue?

Thanks
I have been running into the same problem in my truck, everything works great when everything else is off but as soon as I fire the truck up there is lots of interference over the radio, not so much with the intercom though. I tried different power and ground locations but nothing seemed to make much of a difference. I was told to give an in line filter a shot. PCI sells a kenwood KLF-2 noise suppressor on their website for $40, so I ordered it, and should be coming in today and tomorrow. When I get it I'll wire it up and let you know if it makes a big difference! ImageUploadedByTapatalk1342472105.656813.jpg
 

Jack

Well-Known Member
The other trick to try is removing the ground from the intercomm. It will get it's ground thru the cable to the radio and get rid of the ground loop that can cause whine.
 

manicmechanic

Well-Known Member
A funky trick that worked years ago was to feed the power to the radio through the primary side of an old non resistor ignition coil, filtered the noise and you had a spare coil.
 

Baja Fool

Well-Known Member
The other trick to try is removing the ground from the intercomm. It will get it's ground thru the cable to the radio and get rid of the ground loop that can cause whine.
Couple of years ago that's exactly what I did and my noise went away. Imagine that...
 

Weatherman

The voice of desert racing
The other trick to try is removing the ground from the intercomm. It will get it's ground thru the cable to the radio and get rid of the ground loop that can cause whine.
If the intercom is the PCI racing intercom, the Comlink 6, this is exactly what you have to do. Remove the ground to the intercom! It's in the directions! But only women read directions. Have your girlfriend/wife do the installation. If you still experiance noise, call PCI Scott or Gerardo.
 

zjohnson

Well-Known Member
Thanks Bob, I had a friend wire the car for me and I guess he overlooked this step. I talked with someone at PCI who was very helpful and told me to remove the ground on the intercom, won't have a chance to try it until tomorrow.

Thanks again for the help
 

pkonopasky

Well-Known Member
Thanks Bob, I had a friend wire the car for me and I guess he overlooked this step. I talked with someone at PCI who was very helpful and told me to remove the ground on the intercom, won't have a chance to try it until tomorrow.

Thanks again for the help
Don't know if removing the ground wire worked for you, but I did try out that kenwood filter and it made a night and day different in my truck
 

BSchlimme

Well-Known Member
If the intercom is the PCI racing intercom, the Comlink 6, this is exactly what you have to do. Remove the ground to the intercom! It's in the directions! But only women read directions. Have your girlfriend/wife do the installation. If you still experiance noise, call PCI Scott or Gerardo.
Bob,
100% agree with you on the instructions but......

Since the ground is not necessary why not just terminate it(i.e. cut it off) so that there is no confusion?

After 5 years of owning my car I'll have to see if mine is wired in. Pretty sure it is. Had one hell of a wine going towards the end of NORRA this year. Seemed to get worse starting on day 3 for whatever reason.
 

Weatherman

The voice of desert racing
Ben - in answer to your question why, "not cut it off?" P C I sells many intercoms where no radio is involved, hence the necessary ground wire. When used with a radio, the Comlink 6 Intercom gets its ground from the mike jack of the radio and needs the 16 gauge black wire from the intercom cut so no ground loop exists. In other words, two sources of ground causing the ground loop and thus the whine.

Many times we have found that an outside pseudo wiring genius saw the ground wire cut and re-attached it causing the new whine. As for day three the battery was less than it was to begin with and would attest to your problem.

Lastly, the 'wine' you had towards the end of the race, should have waited until after the race! You shouldn't wine and drive!!!!!!!!!!!!!!!!!!!!!!!!!
 

jps1145

Well-Known Member
Ben - in answer to your question why, "not cut it off?" P C I sells many intercoms where no radio is involved, hence the necessary ground wire. When used with a radio, the Comlink 6 Intercom gets its ground from the mike jack of the radio and needs the 16 gauge black wire from the intercom cut so no ground loop exists. In other words, two sources of ground causing the ground loop and thus the whine.

Many times we have found that an outside pseudo wiring genius saw the ground wire cut and re-attached it causing the new whine. As for day three the battery was less than it was to begin with and would attest to your problem.

Lastly, the 'wine' you had towards the end of the race, should have waited until after the race! You shouldn't wine and drive!!!!!!!!!!!!!!!!!!!!!!!!!
This brought up a good question... I've had the Comlink 6 in my racecar for awhile and just added an Icom radio. should I cut the ground wire to the intercom now?
 
Not specific to the intercom, but I generally build my own noise filters for CB and Amateur applications. It doesn't take much more than a capacitor and inductor inside of a small box. All usually available at Radioshack. Another thing that will help the intercom audio is the use of shielded wiring.
 

zjohnson

Well-Known Member
Update on this. Followed the directions (holy crap) and cut the ground from the intercom. After testing, the car was still making some engine noise. Rethought the problem, one of my good friends is an electrical engineer and asked the simple question as to how the alternator is wired. Its grounded thru the engine to the trans to the chassis on a VW car, right? Well, the car has been powder coated so the ground was intermittent. We ground off the powder coat and added a ground strap for the trans to the chassis. BINGO!!! Raced at the record race and had no issues with engine whine!!

Thanks for the tip weatherman!!
 

atpalmer

Well-Known Member
If the intercom is the PCI racing intercom, the Comlink 6, this is exactly what you have to do. Remove the ground to the intercom! It's in the directions! But only women read directions. Have your girlfriend/wife do the installation. If you still experiance noise, call PCI Scott or Gerardo.
So the 4 link pro elite does not need the ground cut if its plugged into the radio?
 

green787

Well-Known Member
In audio terminology we "lift" the ground.... Lifting the ground (shrink wrap, or electrical tape over the connector) on the intercom removes the ground loop between the radio and intercom, which acts like an antenna picking up any errant RF from the Alternator of other sources.......
If you have loose ground connections on the rest of the car, they could be radiating RF, especially if a little silica sand is between the loose connections acting like a crystal radio, and your antenna could unintentionally pick up Mexican radio stations....
Also by not having a ground strap between the chassis and trans/engine you are probably achieving ground for your entire chassis through your black intercom wire.... "Cutting" that wire could cause your car to not run..:cool:
 
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