Radio interference, I'm out....

luigi164

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Installed a new radio from Retrosound. Everything works well until....I start the car. With the engine running I have a interference which I cannot figure out.
There's a constant crackling sound in the speakers. Also with the volume on zero. Happens in all three speakers, 1 front dash en 2 in the back.
Now it comes: when I hit the brakes (brakelights on) it becomes worse ??? No other accessoirie affects the noise.
My first thought is a ground issue. I connected the radio on several different grounds and 12 volt sources. Makes no difference.


I recorded a video of the front speaker you can see, or more hear, here:
When the crackling goes louder I hit the brakes.

Hope somebody here recognizes this and can help me.

Regards, Luigi
 

CBODY67

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Is the voltage regulator the stock points style?
 

Davea Lux

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Could be the points opening and closing on the factory regulator. You should do the electronic regulator conversion with the pertronix in any case. A shorted alternator or loose spark plug wires will also cause a static issue on the radio. Start with the regulator and proceed from there.

Dave
 

NY69

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First place I would start is to freshen up the ground contacts of your taillights.
And, if you didn't already do it, you might want to put a ground cable between your engine and the body.
 

thrashingcows

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I agree with NY69...you can never have enough grounds, and make sure to clean all your current ones and ensure they have a nice clean connection from battery post to engine, to rad support etc.

Also was there not supposed to be a condenser/suppressor hooked to the coil to mitigate power feedback from the ignition system?
 

Big_John

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Ignition static will go up and down with engine RPM.

This sounds like interference from the charging system, so it could be the voltage regulator (since it's a stock version with points) or a bad diode in the alternator will cause some AC voltage leakage into the DC system. Another source is the mechanical voltage limiter that supplies 5 volts to the instruments under the dash.

To check for the AC leakage, a voltmeter set to the smallest AC range and check the voltage across the battery terminals with the car running. That should be less than .1 volts AC.

You could also disconnect the field wire(s) to the alternator and try that. That should eliminate the alternator and regulator from the system.

You may need to research some noise suppressors to add where needed.

All that said, I'm not a fan of the Retro Radio stuff. It wouldn't surprise me if it's a radio problem.
 
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Big_John

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Thinking a little more... If that doesn't show where the problem is, pulling the fuse for the instruments should shut of the dash voltage limiter to see if that's it.
 

70NEWYORKER

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Radio case must be well grounded. I always use a capacitor in the power supply going to the radio.


Putting a cheap filter in the hot wire can eliminate a lot of the noise in the electrical system. Cheap or solid core ignition secondary wires will cause a lot of noise too.
 

1970FuryConv

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Factory Radios for 1970-1973 grounded through the bracket bar between the back of the radio and dash shell.
20171018_165908 Ground.jpg

If that bracket is not present, I would run ground wire to passenger side of firewall.
I agree with doing the electronic voltage regulator conversion with voltage regulator mounted on firewall. Then I would run a ground wire from the voltage regulator on the engine side of the firewall to the back of one of the engine heads.
PXL_20210317_190237124.jpg
 

Loadrunner

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I'm dealing with a staticky radio also. I have the antenna wire routed well away from the distributor - unlike previous owner - and just upgraded the wires with no change. '69 318 w points and mechanical reg.

Good tip on cutting field current, I try that.
 

luigi164

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Factory Radios for 1970-1973 grounded through the bracket bar between the back of the radio and dash shell.
View attachment 557415
If that bracket is not present, I would run ground wire to passenger side of firewall.
I agree with doing the electronic voltage regulator conversion with voltage regulator mounted on firewall. Then I would run a ground wire from the voltage regulator on the engine side of the firewall to the back of one of the engine heads.
View attachment 557416
I have that voltageregulator and is grounded well, have that bracket from radio to dash also...
 

luigi164

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Radio case must be well grounded. I always use a capacitor in the power supply going to the radio.

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Putting a cheap filter in the hot wire can eliminate a lot of the noise in the electrical system. Cheap or solid core ignition secondary wires will cause a lot of noise too.
I have this one from Amazon and didn't solve the problem.
https://www.amazon.nl/gp/product/B07S7VV12W/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
 

Loadrunner

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pulling the fuse for the instruments should shut of the dash voltage limiter to see if that's it.

The little known IVR. I personally think Chrysler's way of working out pulsing DC to variable grounds was a great way to do it, very easy to troubleshoot.
 

'66 Fury I

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This may be helpful, or serve as comic relief. Years ago when installing 8-track players in a 74 Fury III and a 75 Fury (B body), I encountered similar interference. My solution was to install an old ignition coil (Mopar of course!) in series in the power line. It woked! Lindsay
 

luigi164

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This may be helpful, or serve as comic relief. Years ago when installing 8-track players in a 74 Fury III and a 75 Fury (B body), I encountered similar interference. My solution was to install an old ignition coil (Mopar of course!) in series in the power line. It woked! Lindsay
Can you please explain further on how to ? I'm open for all possible solutions...
 

'66 Fury I

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Sure! I cut the power "in" wire crimped a ring terminal on each side of the cut and connected the terminals, one to each of the low voltage terminals on the ignition coil. The coil was used as a"choke" coil. A term I learned from my father. Lindsay
 
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