CB Installation Problems

[Bob Grieb]

I have installed a CB Radio in my Model A and it will function when the ignition is off however when I start the engine it will not function. I have checked ground and it is good. Any ideas on what I might look for.

Thanks for your help

Bob

[Tom Wesenberg]

Does it power down, or is the static too much for the CB?

You may have to use carbon wires and static suppressors to run a CB in a Model A.

[Bob Grieb]

It just stops receiving/transmitting voice but there is no static.

Thanks for your response!

[Bob Grieb]

I have installed a new radio and I get the same result.

[Doug Linden]

Where did you connect the CB power wire? Some aftermarket Model A ignition switches provide an accessory power connection and a CB will not work off this terminal.

[Bruce Adams]

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Is the CB's dial lamp lit when the engine runs?

[Bob Grieb]

The CB is connected thru a hot distribution panel mounted on the firewall not thru the ignition switch.

The dial lamp does light when the engine is running.

Thanks

[fastroadster]

Where have you connected your "Hot wire" on the CB. Hook it directly to the pos side of battery. The CB does not draw that much amp. that you have to worry about.

[Tom Wesenberg]

Have you tried adjusting the squelch with the engine running?
I haven't used my CB since the early 80's, and that was in a modern car, so I can't be of much help.

[Gary WA]

CB Radio Installations can be found for Model A's in Model A Ford Mechanics Handbook VolII Les Andrews Green Book. Pg 4-73

[MikeK]

Some suggestions from my mobile ham days- 1) The CB's IC's may be overwhelmed by supply noise. Check the alternator for a bad diode. Even if the output is an even ripple (normal for an alternator) you may need an L-C filter in the power lead. 2) Are you running a one-wire alternator? You may have one with a regulator set so high the CB's internal supply shuts down from over-voltage. The idiot light would remain on but no function. 3) As Tom said, add suppression to the ignition system. 4) Many of the newer radios have all plastic cases rather than steel boxes. They do a poor job of shielding the circuitry from RF. Try wrapping aluminum window screen around the sides and back to make a Faraday cage. Make sure the screen is grounded.

[KansasRick]

The battery is the best filter capacitor on the car. Connect your CB directly to the battery with an in line fuse. Use the on/on switch on the radio. This method eliminates any induced electrical generated system problems the best you can do. Test it first before you hook it all up permanently to make sure it works. I am a retired two-way radio tech and have seen this work in various machines before when all kinds of fancy in line power filters and other techniques failed. Good luck.

[KansasRick]

Another thing you need to check is how you run your antenna coax. Be careful not to run the coax near devices on the firewall where the ignition system noise can be induced in the coax. An example is running the coax near the wires in the instrument panel or the firewall where the coil is located - even on the inside. Try to keep the coax of you antenna away from any place that has a source of induction of electrial ignition signal noise induction. Coax is supposed to be shielded but newer less expensive coax doesn't seem to work as well as it used to. One last thing......try not to mount the radio too close to the instrument panel. Anymore the less expensive digital radios are more accessible to electronic interference from ignition systems too. You might find your problem after all this is your radio is sensitive to all the electrical interference in the car. That might been hard to fix...make sure you have a good chassis ground on the radio to the car and your antenna has a really good ground. That is the last thing I can think of. Bond all the radio system grounds for noise is important. Hope this helps.

[katy]

Try running the CB from a separate source w/the engine running. This will tell you if the problem is in the power supply or not.

[Bob Grieb]

Thanks for all the feedback/help. I will look at all of the suggestions and get back with a response on where I am in the process.

Bob

[Bob Grieb]

I tried connecting directly to the battery and it had no effect. I do think that the point that MikeK regarding the alternator regulator being set to high may be the problem. I have two model A's and the radio works in one but not the other. I will look into a L-C filter today.

Thanks

[Tom Wesenberg]

It would be best to fix the alternator for the correct voltage, but you can also buy a voltage limiter to connect to your CB power line.

I bought a 3 volt limiter to run my 12 volt electric fuel pump on my 6 volt battery. This supplies the correct low pressure and volume I need to run my Studebaker engine.

[katy]

What's the system voltage w/the engine running?

[Bob Grieb]

When I measure the voltage at the alternator I get a steady reading of about 13 Volts from the Model that has the working CB installed. When I measure the voltage at the alternator of the Model A with the non performing CB I et very erratic readings.

I am unfamiliar with a voltage limiter for the CB. Logic tells me this must be the problem but I do not know what to purchase. Can you be more specific as to what I need to purchase? Thanks for all the help and patience.

Bob

[MikeK]

Purchase a new alternator.