Worldwide DX Amateur Radio Forums - Ham - CB - HF - VHF - UHF

One thing to look at.

Have a shop with a modern charging system tester look at your alternator's output.

They will check it for maximum power under load and look at ripple in the DC output. If there is a lot of ripple and the peak power is down the alternator could have one bad rectifier diode. It will still keep the vehicle charged unless you sit at a red light with the defrogger, wipers and lights on.

The ripple will show up as whine in your radio and give you a nasty hangover.

so let me see if I am looking at this correctly. on this home made filter, there is a black wire coming out (that goes to the positive side of the battery) and the 2 ends of the red line are inline from where your 12+ source is to the radio?

No, not quite right. One of those red wires goes to the (+) side of the battery, the other red wire goes to your radio. The black wire (-) goes to the negative side of the battery, or the vehicle's ground (assuming that the the thing is a negative ground to start with).
- 'Doc

Just like it says under the last photo: the red lead connected to the capacitor goes to the radio. The other red lead goes to the battery. The black lead goes to ground. Keep connections at the radio end as short as is practicable.

__________________
If you're like everybody else,
you're about average.
73 de K7KBN

DUH!!! was late last night when I was reading it. now that I look at it, it makes perfect sense!

Did the filter help with your alternator noise?

turns out it wasn't alternator noise, but noise coming in on my antenna. I have a 2006 Ford F150 and I have since found out that the Fords are notorious for fuel pump noise.

am going to ground the daylights out of this truck when it warms up a bit. probably a couple from the bed to the frame, cab to the frame, exhaust to the frame, and whatever else I can think of.

I think the fuel pump is causing part of my static also. Mfd2727, here is what mine does, let me know if yours does the same.

With my Jeep running, I have to squelch about 1/2 way to get rid of the static. If I shut my Jeep off (key off, CB on) I get very little static. If I then turn the key on but do not start the Jeep, I get a little more static. As soon as I start the Jeep all the static comes back. I tried unplugging the antenna and most of the static goes away.

I get a little alternator static I can hear when revving the motor so I might go ahead and make one of these to see if it helps. But what can be done to eliminate noise coming in over the antenna? I plan to redo the ground on my antenna because it is getting a little frayed where it bolts to the body. But what else can I do?

You can check the spark plug wires and make sure they aren't too old and cracking. Replace if questionable - especially if they are too stiff/hard. Back in the 70's, most of the cars on the market came with a condenser/capacitor from the alternator ground to the field connector. This was used to reduce noise. I'm sure it can be done if necessary. Also, run a ground wire from the tip of the exaust pipe to chassis ground - this can also help.

__________________
What gear do I use?
BASE: Icom IC-718 & GAP Titan DX, Yaesu FT-8800R & Diamond X50A, Magnum OmegaForce S45 & IMAX 2000 w/Astatic D104/TUP9.
MOBILE: Galaxy DX99V & Wilson 1000 w/Astatic D104-M2, Yaesu FT-8800R & Diamond NR-770.
"...WR-11 San Jose CA - Standing By..."

A couple things haven't really been covered, so I'll toss in my $0.02 worth. Where is the radio picking up its DC ground? If it's through the mounting screws, are all the mechanical connections nice and bright? I always run a separate lead with lugs and star washers from the chassis to a good, *close* vehicle chassis ground. And I make sure that part of the chassis has a very low DC path back to the battery's negative pole.
Some folks use the long (and frequently fused) black/negative power lead that comes with their rig (common on ham gear) to run all the way to the battery, just like the red. This is OK as long as the wire size is actually big enough to carry the current needed for the max current needed to run the transmitter on highest power over the entire DC power path. If the radio is 12 feet from the battery, that means it's a 24-foot loop, and can mean a significant voltage drop when transmitting. And if there's any resistance at any of the crimp connectors, fuse holders, battery terminals, etc., you'll lose some of the.....wait for it...... noise isolation!.... that the battery would usually provide.
As for the fuel pump, fuel gauge sending unit, wiper motors, etc. : If you can get to them easily enough, solder a .01 uF disk capacitor across their power leads as close to the units as possible. The little motor whine from the wipers, the tick-tick, tick-tick from the sending unit, and the smaller whine from the fuel pump, will get filtered out at their sources.
Is everyone putting their antennas at the rear of the vehicles, or at least on the roof? Hood grooves may be convenient, but the closer you put the RF receiving element of the radio to the spark/RF generating element of the car, the more of it you'll hear.
Just my thoughts. I'm new here, but have been a two-way tech for 35 years and a ham for almost 50.
HTH
diddly dahdidah
dit dit
-- Zygoma --
Statesville, NC