CB and RF

[Bill_20]

Have a CB that picks up the fuel pump RF. I know this isn’t a power issue and have verified this with a portable CB unit. Only when the fuel pump is active is the interference present. Any ideas on filters for CB units that won’t kill my range?

 

[old_man]

First off put a DC filter right at the fuel pump and make sure the negative lead is grounded to the body well and near by. If it is an in tank pump and the tank is metal, the noise is not radiated RF but rather conducted RF through the power wiring.

Ground your radio well and run a DC filter right at the radio.

 

[Bill_20]

First off put a DC filter right at the fuel pump and make sure the negative lead is grounded to the body well and near by. If it is an in tank pump and the tank is metal, the noise is not radiated RF but rather conducted RF through the power wiring.

Ground your radio well and run a DC filter right at the radio.

It sounds like you have encountered something similar in the past. I would like to explain a few things on the power to get your opinion.
I’ve made sure that the power is clean and a direct connect to the battery. The fuel pump has a good ground as well.
I have checked to make sure interference is received through the coax/antenna by disconnecting the antenna from the CB unit. This is done while it’s powered up and vehicle is running.
The CB unit will go quiet when the coax/antenna is disconnected.
The handheld unit picks this up as well.
This is why I’m thinking a DC filter will not solve the problem. Am I wrong for thinking this?

 

[M Rose]

It sounds like you have encountered something similar in the past. I would like to explain a few things on the power to get your opinion.
I’ve made sure that the power is clean and a direct connect to the battery. The fuel pump has a good ground as well.
I have checked to make sure interference is received through the coax/antenna by disconnecting the antenna from the CB unit. This is done while it’s powered up and vehicle is running.
The CB unit will go quiet when the coax/antenna is disconnected.
The handheld unit picks this up as well.
This is why I’m thinking a DC filter will not solve the problem. Am I wrong for thinking this?

Yes you are wrong thinking this... the DC filter filters out RF noise generated from the transmitting station (your car and CB). When the filters don’t work is when RF signals are generated elsewhere and traveling through the air.

 

[Prerunner1982]

A common mode choke, or two may be another option.

Common Mode Currents

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