CB Noise Question

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Sep 2, 2008 | 10:26 PM

#31

1975StroppeBaja

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From: WV

Quote:

Originally Posted by krewat

Actually just re-read what you posted, when I asked if the noise go up and down with the engine speed, I meant frequency-wise, not volume-wise.

Yeah, the amount and tone of the noise remains constant at all engine speeds.

Quote:

Originally Posted by krewat

Anyway, what you have seems to be electronic interference, if it's somewhat of a tone, something in the truck is generating that tone. Could be the PCM or another electronic gizmo. Got any anti-theft stuff that's not stock? Cell phone charger plugged in all the time?

I do have a home-brewed temperature monitor that I designed & built. I've checked the noise with it turned on & off and the noise levels are about the same. Otherwise, no other known non-stock electronic things powered up. I might borrow a spectrum analyzer from work and snoop around to see if I can find the culprit.

Quote:

Originally Posted by krewat

Better yet, is the noise there when the ending is NOT running (and the ignition key is NOT in the ON position) ???

I'll have to rework my wiring to test this since I have to have the key in the ON position to power the CB. I'll try to check that tomorrow evening. But, the noise level is quite a bit lower with the engine turned off (but the key in the ON position). With the engine running, I get a higher noise level and the higher frequency tone is introduced.

Quote:

Originally Posted by krewat

The ferrite cores that jwrench posted could help alot. I'd check into a more sophisticated noise filter hooked inline with the power supply to the CB, like the ones used for car stereos (if they can handle enough amperage for transmitting). They are basically a simple filter, an inductor inline in the +12V, with a capacitor from the output of the inductor to ground.

I thought that verifying that all the noise went away with the antenna coax unplugged ruled out that the noise is coming in on the power supply wiring..? Some type of filter or ferrite bead certainly wouldn't hurt though so maybe I'll try something like that.

Keep those ideas comin'! Thanks again!!

Sep 2, 2008 | 10:34 PM

#32

krewat

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From: Long Island USA

Quote:

Originally Posted by 1975StroppeBaja

I thought that verifying that all the noise went away with the antenna coax unplugged ruled out that the noise is coming in on the power supply wiring..?

Ah... didn't see that ... Did you have the squelch off when you tried that? Probably, but have to check

Sep 2, 2008 | 10:41 PM

#33

1975StroppeBaja

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From: WV

Quote:

Originally Posted by krewat

Ah... didn't see that ... Did you have the squelch off when you tried that? Probably, but have to check

Haha... yeah I did. BUT, I did claim premature victory a few times during all these tests, only to find out I had the squelch turned up

Sep 7, 2008 | 08:44 PM

#34

1975StroppeBaja

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From: WV

Quote:

Originally Posted by jwrench

I'll try not to write a book here, but as a general class ham, and a powerstroke owner here is what I would do. First, I would unplug the coax from the radio and listen for the noise. If it's still there, go to radio shack and get two of these. One for the positive lead, one for the negative.

RadioShack.com - Cables, Parts & Connectors: Component parts: Inductive products: Snap Choke Core

Well, the noise did go away once I unplugged the coax, but for completeness I put a few of these snap-on type ferrite cores around my CB power/gnd wires. They were kinda big, like the one shown here:

FERRITE SPLIT BEAD, 0.4"ID (10MM) | AllElectronics.com

I only had two of these cores and my CB has three wires (to +12V's and a GND) and they are all bonded together (picture a large 3-conductor ribbon cable) so I just put all three through one core. I did loop the three wires through the core once. I put two cores in a row setup like this and it is VERY obvious that it helped a bunch. I wasn't expecting it to make that much of a difference based on the tests I've done so far.

I might try some smaller ferrites, separate the wires, and wrap them more times.

Thanks for the suggestion jwrench!

Sep 7, 2008 | 09:29 PM

#35

krewat

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From: Long Island USA

I'd still try to set it up so you can power on the CB without the engine running AND without the ignition key in the ON position.

Because the ferrites helped, I suspect it's power-supply or ground related.

Sep 7, 2008 | 10:24 PM

#36

1975StroppeBaja

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From: WV

Quote:

Originally Posted by krewat

Rats. I forgot about that test. I need to put up a sticky note reminding me to do that next chance.

Sep 13, 2008 | 10:46 PM

#37

jwrench

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Joined: Aug 2008

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From: Clarksville, TN

I was gonna say try a magnet mount antenna up on the cab away from your IDM (injector amplifier), but I just noticed the 5.4L in your sig so I had to edit this post. Glad the chokes helped. Good luck with it.

Sep 14, 2008 | 08:16 AM

#38

1975StroppeBaja

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From: WV

Quote:

Originally Posted by jwrench

Yeah, I saw that suggestion in your earlier post and forgot about it amongst all the other posts. I had meant to ask you if I had one of those since I'm a gasser.

I did try powering the CB from a separate battery and it seemed to be about the same as far as the general noise goes. The only thing I noticed was that the little blips of noise that happen when the power door locks engage went away.

I tried some additional chokes, separating the wires, and different grounding and it was about the same. So, I think it might be as good as I can get it. I have noticed over the past week that I've been picking up alot more traffic on the CB so I guess that's good!

Thanks again guys!