RF noise on 280Z

[TomoHawk]

I tried out my handheld CB radio for a club outing next week, and I'm getting loud buzzing from the engine. It has stock ignition, resistor plugs (I think) and I plug the CB into the cigarette lighter plug.

I was thinking of adding an extra cigarette lighter jack on the riser hehind the seats.

There is no buzzing on the stereo system.

Any ideas?

thxZ

Edited September 6, 2009 by TomoHawk

[FastWoman]

You can put a big choke on the power supply to the CB. Better still, you might run both your (fused) +12 and your ground directly from the battery. If you do that, I bet you won't need a choke. Twist your + and gnd wires together, and keep them away from the ignition circuitry, including the ignition module on the righthand kick panel.

Before doing these things, though, you might want to make sure the noise is through the cigarette lighter and not RF interference. Try the CB on (internal) battery power and make sure you don't get the same thing.

Edited September 7, 2009 by FastWoman

[TomoHawk]

I had a ham radio repair guy help me with this.

First we tuned the antenna to the radio, then we checked the transmission quality with & without the engine on.

The noise was definitely IF noise. I got a power line filter from a local audio store, but the guy (kid) first handed me a gadget that hooks up to the alternator. How likely is it for you to get noise from the (new) alternator? Could you hear that on the stereo, and what should it sound like? The alternator has the noise cap on it, but I think it's an old one. Can I just replace it with a generic one from the parts tore? Same deal with the cap on the ignition coil. Those two things could be the problem, and easiest to fix ( without digging into the dash wiring.)

thxZ

Edited September 14, 2009 by TomoHawk

[FastWoman]

Hey Tomo,

The fact that you have a new alternator shouldn't make any difference. They're all noisy, old or new. Alternator noise sounds like a soft, somewhat high-pitched whine that's proportional to engine speed. Yes, you can hear it through many stereos. Other stereos have really great power conditioning and are rather immune to supply noise. I would think generic caps should be fine for your alternator and coil.

Another possible noise source is your wires and plugs. The wires are rather obvious -- different varieties with different noise properties. The resistive types might be a bit quieter than the inductive/coil type. You can also try resistive plugs (e.g. BR6ES-11 (?), rather than B6ES-11 (?), the difference being the "R" for "resistive."

A choke on the 12VDC line never hurts. Go to a different audio store, and make sure they hand you a choke, not a cap.

[FastWoman]

Tomo, here's a choke that would probably work for you:

http://www.surplussales.com/Transformers/PowerChk-3.html

Second from the top, on the left -- 50uH, 20A, $6

You could run a couple of them in series for even more noise suppression if you want.

[TomoHawk]

I'm going to start with the basics; a new cap on the alternator, and a new one on the ignition coil. The alternator is a no-brainer with a generic cap, but the one on the coil is puzzling; it's axial with a wire out each end, so The guts are a mystery. I'm trying a generic condenser on the coil, directly connected, in the way the wiring diagram shows, and so far no problems, but I haven't check how quiet it is.

I will look up the numbers on the spark plug & wires to see what's in those.

thxZ

Edited September 16, 2009 by TomoHawk

[TomoHawk]

Oddly, my spark plugs are currently NGK BPR5ES and the wires are Beck-Arnley Mag cores...

So, after putting on some noise caps on the alternator and coil, I still have the radio noise on my CB.

[sblake01]

IIRC, isn't a Mag core wire an unsupressed copper core similar to a 'race' wire? Could be part of your problem.

[TomoHawk]

It's the Beck-Arnley Brand from Autozone, I think. There isn't any noise on the stereo, but that could be another thing. I'll go to NAPA and get some regular stuff. Or is BD an appropriate source for ignition wires?

thxZ

A document from Beck-Arnly I just found on my wires: http://www.beckarnley.com/marketing/ignition%20wire%20sets.pdf

Edited September 16, 2009 by TomoHawk

[sblake01]

Those appear to be a quality wire at least going by their description and they shouldn't cause any problem with the stereo. I don't have any experience with CB radios. Likely they are different from a car stereo as in what type of signals/frequencies/interference would affect them.

[TomoHawk]

I think I'll put the Bosch wires back on. I don't remember having cb noise before.

Edited September 17, 2009 by TomoHawk

[TomoHawk]

It was the ignition wires.

I tried the handheld CB in the new car and it was quiet except for some static like noise, and it picked up noise from the seatbelt buzzer, fuel pump and even the power window motors! I think that was because of the cheap radio. Then I swapped the Bosch wires on the Z, and tried the CB in there. It was just as quiet, but you could hear the Z's seatbelt buzzer again.

Reception seems to be improved too, as I tested that by driving a 1mile loop while talking to a friend.

I will look into a better type of handheld for the future. I might still put the noise supresor on the one 12V juck to have a very quiet power source for digital stuff like a laptop.

rhxZ for the discussion.