The Ford Barn

Pat Martone · 08-03-2012, 05:49 AM

For group touring purposes, I have installed a CB radio in my Model A.

While it works great when the engine is not running, the ignition noise (from spark plugs or coil?) makes the CB radio unusable.

I do not think I am experiencing alternator ("whining") noise; I am convinced it is spark noise.

I have tried power line filters without success; it appears the ignition noise is entering the radio through the antenna connection on back of the radio itself, since when I disconnect the antenna, some of the ignition noise is attenuated.

Has anyone else experienced and resolved this problem?

Thank you.

western77 · 08-03-2012, 06:23 AM

Try the round distrubutor cap and the insulated wires.

V4F · 08-03-2012, 07:58 AM

they make filters for that , but never had good luck myself . radio shack & others have them .......

30cabriolet · 08-03-2012, 08:04 AM

I can't give you an instant fix for this, but I can point you in hopefully the right direction. I recently built a microprocessor based (PIC chip) turn signal box to run LED signals. When the car was running the RFI would cause the box not to work. I ended up doing 3 things that I suggest you look into. First, I added ferrite beads to all the wires to suppress the interference. Second, I added more capacitor filters at the input and output of the power supply to filter out unwanted frequencys. And lastly, I actually lined the control box with lead tape to keep out stray signals.

If you do a search for ferrite beads and HAM radios you will see a lot of discussion on RF interference.

John Stone · 08-03-2012, 08:24 AM

Newer radios don't have the filtering that the old ones had.

On my 400A, I found a resistor type coil wire helped. Also make sure everything has a good ground. Originally I was running a diode cutout on my generator and it was causing the problem but it was more of a whining noise. Must have been a bad diode. The best fix was an old 23 channel radio.

Mike V. Florida · 08-03-2012, 09:59 AM

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Quote:

Originally Posted by western77

Try the round distrubutor cap and the insulated wires.

The noise is coming in through the antenna so a power filter won't help. "Modern" cap and wires should help alot.

Pat Martone · 08-03-2012, 11:27 AM

Thanks for the info.

Yes, the ignition noise is entering my CB radio via the antenna connector on the back.

I do not want to switch to a modern distributor and spark plug wires, so I will try to solve the problem another way.

I wonder if I can somehow insulate (or shield) the radio, or ignition wire, or coil?

Tom Wesenberg · 08-03-2012, 11:37 AM

Quote:

Originally Posted by Pat Martone

Thanks for the info.

Yes, the ignition noise is entering my CB radio via the antenna connector on the back.

I do not want to switch to a modern distributor and spark plug wires, so I will try to solve the problem another way.

I wonder if I can somehow insulate (or shield) the radio, or ignition wire, or coil?

You might try a carbon coil wire to see if that helps. If you make your own carbon coil wire be sure you poke solid wire into the carbon ends at least 3/4" or so and have the metal terminals touch this wire as you crimp them to the wire. Bend the wire over and lay it tight to the outside of the carbon coil wire so when you crimp the terminals it's in solid contact with the wire.

walt jones · 08-03-2012, 12:06 PM

I use a seperate small 12volt rechargable sealed lead-acid battery rated at 7.2 amp hours. I have used this on tours lasting several days with no problems. There is not near as much noise as if the radio were connected to the car battery. It will need charging from time to time. A small 12v charger can be used for this.

Logan · 08-03-2012, 02:45 PM

Would running the ignition On it's own circuit not eliminate this? I know mine doesn't do it anymore with the electronic ignition On it's own circuit.

Bruce Adams · 08-03-2012, 03:50 PM

I don't have this problem with any of my SWAP MEET CB radios.

I wonder if the 1970's CB's had more filters built in.

I also do not have this problem with new portable CB's working into a magnetic mount antenna.

I have standard spark plug connectors, 6 volt sytem, and a 6 volt alternator.
I generally use a 12 volt "Jump Box" as my 12 volt source.

MrTube · 08-03-2012, 04:03 PM

IMO building a simple filter using an inductor and capacitor for your power supply could help a lot.

At the same time it may ALSO be entering via the antenna which would be a whole other issue. Your dealing with an AM radio which is highly susceptible to ignition noise.

Mike V. Florida · 08-03-2012, 06:14 PM

Quote:

Originally Posted by MrTube

At the same time it may ALSO be entering via the antenna which would be a whole other issue. Your dealing with an AM radio which is highly susceptible to ignition noise.

When I asked this is what he said;

"Yes, the ignition noise is entering my CB radio via the antenna connector on the back."

jmeckel · 08-03-2012, 08:01 PM

Not an easy thing to get rid of on a old car. Try carbon coil wire. If that does not help you will need to go to modern resistor plug wires and round dist cap. You also maybe picking up noise from the points and roter. Modern cb's have very bad recevers with little to no front end selectivity. An older well built one would be better, however they are only 23 ch at the best. Or give up on the cb idea and use the little fm family radio service portables, they are fm so ing noise does not bother them much. There are some things that just do not work well in old cars new cb's and am radios are some. Not that it can't be done, just how much pain are you willing to go through. I can tell you from almost 30 years in the communications bussness that rfi in a older vehicle is a lot of work and expense to cure and some times it never really goes away.

Jerry in Shasta · 08-03-2012, 08:15 PM

A radio with "noise blanker" feature, should solve the problem. Cobra makes radio with this feature.

JB

Pat Martone · 08-03-2012, 08:57 PM

Yes, my CB radio, a Uniden Bearcat BC680, does have a ANL/NB (automatic noise limiter/noise blanker) switch and it reduces the ignition noise quite a bit, but does not eliminate it completely.
I wonder if my Petronix "flame-thrower" 40,000 volt ignition coil (12v) is the source of the ignition noise; maybe a plain-Jane no-name coil from Autozone will produce less "noise"?
I know 12volt conversions are not popular, but can anyone recommend a 12v ignition coil worth trying, and where I can get one?
Thank you.

BILL WILLIAMSON · 08-04-2012, 12:05 AM

Vintage transistor radio was noisy in the car I sold, with round cap & regular wires.
On my present '29 I'll use the round cap with resistor wires & resistor coil wire & see if it helps. (Same radio) Bill W.

Bruce Adams · 08-04-2012, 07:54 AM

In the FWIW department, sometimes I want to listen to the AM baseball game on my cheap AM transistor radio while driving, and while there is a lot of ignition noise when the radio is in the cockpit, I found I can strap it to the peg on the open cabriolet windshield and it becomes quite tolerable.

Pat Martone · 08-04-2012, 10:12 AM

I wonder if there is some kind of insulated coil wire I can try?
I could not find one at the local parts stores.
I wonder why the 12v coils at auto parts stores (for 1960s cars) say right on them to use a resistor, but they don't sell the resistor?
Or maybe I can try a resistor on my existing 12v coil, but where would I get that?
Is it the same resistor that Les Andrews recommends when converting to 12v while keeping the 6v coil? Since I have a 12v coil, what would the impact be if I used that resistor which is made for converting from a 6v coil to 12v?
Thanks.

Purdy Swoft · 08-04-2012, 11:42 AM

The carbon filled spark plug and coil wires that are used in modern cars are resistor type and are for resisting radio interferance. About the only thing that uses actual metal core plug wires are tractors and race applications. The carbon type wires need to be replaced on modern cars each time the spark plugs are replaced.

The Pertronix flamethrower coil that I use is rated at 3.0 ohm and has a built in resistor. The resistor cuts the voltage down to the points and probably will have no effect on radio interferance. If you wanted to run a performance coil on 6 volt, you would want a coil rated at 1.5 ohm . If you wanted to run an original or a 1.5 ohm coil on 12 volts you would need to use a resistor. Now days, coils are rated in ohm instead of volt . If you run points ignition in a model A, you will need a coil rated at 1.5 ohm for 6 volt or you will have to run a resistor or you will burn the points. If you want to run 12 volts without the clutter of a resistor you will need a coil rated at 3.0 ohm. Snyders offers a balast resistor on page A-145 part number A-12001 and cost seven dollars. If you install a resistor on a flamethrower coil that is rated at 3.0 for 12 volt use, you will greatly reduce the currant to the points and it may not run.

08-03-2012, 05:49 AM	#1
Pat Martone Senior Member Join Date: Jul 2011 Posts: 495	Is there a "cure" for ingition noise overpowering a CB radio? For group touring purposes, I have installed a CB radio in my Model A. While it works great when the engine is not running, the ignition noise (from spark plugs or coil?) makes the CB radio unusable. I do not think I am experiencing alternator ("whining") noise; I am convinced it is spark noise. I have tried power line filters without success; it appears the ignition noise is entering the radio through the antenna connection on back of the radio itself, since when I disconnect the antenna, some of the ignition noise is attenuated. Has anyone else experienced and resolved this problem? Thank you.

08-03-2012, 06:23 AM	#2
western77 Senior Member Join Date: Jul 2010 Location: Grand Rapids Mi Posts: 168	Re: Is there a "cure" for ingition noise overpowering a CB radio? Try the round distrubutor cap and the insulated wires.

08-03-2012, 07:58 AM	#3
V4F Senior Member Join Date: May 2010 Location: ca. Posts: 2,522	Re: Is there a "cure" for ingition noise overpowering a CB radio? they make filters for that , but never had good luck myself . radio shack & others have them ....... __________________ V4f

08-03-2012, 08:04 AM	#4
30cabriolet Senior Member Join Date: May 2010 Posts: 130	Re: Is there a "cure" for ingition noise overpowering a CB radio? I can't give you an instant fix for this, but I can point you in hopefully the right direction. I recently built a microprocessor based (PIC chip) turn signal box to run LED signals. When the car was running the RFI would cause the box not to work. I ended up doing 3 things that I suggest you look into. First, I added ferrite beads to all the wires to suppress the interference. Second, I added more capacitor filters at the input and output of the power supply to filter out unwanted frequencys. And lastly, I actually lined the control box with lead tape to keep out stray signals. If you do a search for ferrite beads and HAM radios you will see a lot of discussion on RF interference.

08-03-2012, 08:24 AM	#5
John Stone Senior Member Join Date: May 2010 Location: Wichita, Kansas Posts: 710	Re: Is there a "cure" for ingition noise overpowering a CB radio? Newer radios don't have the filtering that the old ones had. On my 400A, I found a resistor type coil wire helped. Also make sure everything has a good ground. Originally I was running a diode cutout on my generator and it was causing the problem but it was more of a whining noise. Must have been a bad diode. The best fix was an old 23 channel radio.

08-03-2012, 11:27 AM	#7
Pat Martone Senior Member Join Date: Jul 2011 Posts: 495	Re: Is there a "cure" for ingition noise overpowering a CB radio? Thanks for the info. Yes, the ignition noise is entering my CB radio via the antenna connector on the back. I do not want to switch to a modern distributor and spark plug wires, so I will try to solve the problem another way. I wonder if I can somehow insulate (or shield) the radio, or ignition wire, or coil?

08-03-2012, 12:06 PM	#9
walt jones Senior Member Join Date: May 2010 Location: Kansas City, Mo. Posts: 101	Re: Is there a "cure" for ingition noise overpowering a CB radio? I use a seperate small 12volt rechargable sealed lead-acid battery rated at 7.2 amp hours. I have used this on tours lasting several days with no problems. There is not near as much noise as if the radio were connected to the car battery. It will need charging from time to time. A small 12v charger can be used for this. __________________ Walt

08-03-2012, 02:45 PM	#10
Logan Senior Member Join Date: May 2010 Location: Fort Worth, Texas Posts: 1,055	Re: Is there a "cure" for ingition noise overpowering a CB radio? Would running the ignition On it's own circuit not eliminate this? I know mine doesn't do it anymore with the electronic ignition On it's own circuit. __________________ Cowtown A's

08-03-2012, 03:50 PM	#11
Bruce Adams Senior Member Join Date: May 2010 Location: Northport, NY Posts: 1,597	Re: Is there a "cure" for ingition noise overpowering a CB radio? I don't have this problem with any of my SWAP MEET CB radios. I wonder if the 1970's CB's had more filters built in. I also do not have this problem with new portable CB's working into a magnetic mount antenna. I have standard spark plug connectors, 6 volt sytem, and a 6 volt alternator. I generally use a 12 volt "Jump Box" as my 12 volt source.

08-03-2012, 04:03 PM	#12
MrTube Senior Member Join Date: Jun 2010 Location: New Jersey Posts: 1,471	Re: Is there a "cure" for ingition noise overpowering a CB radio? IMO building a simple filter using an inductor and capacitor for your power supply could help a lot. At the same time it may ALSO be entering via the antenna which would be a whole other issue. Your dealing with an AM radio which is highly susceptible to ignition noise.

08-03-2012, 08:01 PM	#14
jmeckel Senior Member Join Date: Sep 2011 Location: Luck WI Posts: 550	Re: Is there a "cure" for ingition noise overpowering a CB radio? Not an easy thing to get rid of on a old car. Try carbon coil wire. If that does not help you will need to go to modern resistor plug wires and round dist cap. You also maybe picking up noise from the points and roter. Modern cb's have very bad recevers with little to no front end selectivity. An older well built one would be better, however they are only 23 ch at the best. Or give up on the cb idea and use the little fm family radio service portables, they are fm so ing noise does not bother them much. There are some things that just do not work well in old cars new cb's and am radios are some. Not that it can't be done, just how much pain are you willing to go through. I can tell you from almost 30 years in the communications bussness that rfi in a older vehicle is a lot of work and expense to cure and some times it never really goes away. __________________ Jon "If you choose to not decide, you still have made a choice!" RUSH Don't tell me what you know..... Tell me what you have done.

08-03-2012, 08:15 PM	#15
Jerry in Shasta Senior Member Join Date: Jun 2010 Location: (Old)Shasta (Redding) CA Posts: 385	Re: Is there a "cure" for ingition noise overpowering a CB radio? A radio with "noise blanker" feature, should solve the problem. Cobra makes radio with this feature. JB

08-03-2012, 08:57 PM	#16
Pat Martone Senior Member Join Date: Jul 2011 Posts: 495	Re: Is there a "cure" for ingition noise overpowering a CB radio? Yes, my CB radio, a Uniden Bearcat BC680, does have a ANL/NB (automatic noise limiter/noise blanker) switch and it reduces the ignition noise quite a bit, but does not eliminate it completely. I wonder if my Petronix "flame-thrower" 40,000 volt ignition coil (12v) is the source of the ignition noise; maybe a plain-Jane no-name coil from Autozone will produce less "noise"? I know 12volt conversions are not popular, but can anyone recommend a 12v ignition coil worth trying, and where I can get one? Thank you.

08-04-2012, 12:05 AM	#17
BILL WILLIAMSON Senior Member Join Date: Dec 2010 Location: FRESNO, CA Posts: 12,560	Re: Is there a "cure" for ingition noise overpowering a CB radio? Vintage transistor radio was noisy in the car I sold, with round cap & regular wires. On my present '29 I'll use the round cap with resistor wires & resistor coil wire & see if it helps. (Same radio) Bill W. __________________ "THE ASSISTANT GURU OF STUFF"

08-04-2012, 07:54 AM	#18
Bruce Adams Senior Member Join Date: May 2010 Location: Northport, NY Posts: 1,597	Re: Is there a "cure" for ingition noise overpowering a CB radio? In the FWIW department, sometimes I want to listen to the AM baseball game on my cheap AM transistor radio while driving, and while there is a lot of ignition noise when the radio is in the cockpit, I found I can strap it to the peg on the open cabriolet windshield and it becomes quite tolerable.

08-04-2012, 10:12 AM	#19
Pat Martone Senior Member Join Date: Jul 2011 Posts: 495	Re: Is there a "cure" for ingition noise overpowering a CB radio? I wonder if there is some kind of insulated coil wire I can try? I could not find one at the local parts stores. I wonder why the 12v coils at auto parts stores (for 1960s cars) say right on them to use a resistor, but they don't sell the resistor? Or maybe I can try a resistor on my existing 12v coil, but where would I get that? Is it the same resistor that Les Andrews recommends when converting to 12v while keeping the 6v coil? Since I have a 12v coil, what would the impact be if I used that resistor which is made for converting from a 6v coil to 12v? Thanks.

08-04-2012, 11:42 AM	#20
Purdy Swoft Senior Member Join Date: May 2010 Location: Alabama Posts: 8,099	Re: Is there a "cure" for ingition noise overpowering a CB radio? The carbon filled spark plug and coil wires that are used in modern cars are resistor type and are for resisting radio interferance. About the only thing that uses actual metal core plug wires are tractors and race applications. The carbon type wires need to be replaced on modern cars each time the spark plugs are replaced. The Pertronix flamethrower coil that I use is rated at 3.0 ohm and has a built in resistor. The resistor cuts the voltage down to the points and probably will have no effect on radio interferance. If you wanted to run a performance coil on 6 volt, you would want a coil rated at 1.5 ohm . If you wanted to run an original or a 1.5 ohm coil on 12 volts you would need to use a resistor. Now days, coils are rated in ohm instead of volt . If you run points ignition in a model A, you will need a coil rated at 1.5 ohm for 6 volt or you will have to run a resistor or you will burn the points. If you want to run 12 volts without the clutter of a resistor you will need a coil rated at 3.0 ohm. Snyders offers a balast resistor on page A-145 part number A-12001 and cost seven dollars. If you install a resistor on a flamethrower coil that is rated at 3.0 for 12 volt use, you will greatly reduce the currant to the points and it may not run.