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Author Topic: Need help-Ignition noise in F-150  (Read 1617 times)

Posts: 2


« on: January 24, 2002, 06:27:13 AM »

Hi everyone,

I Just installed my Icom IC-706MKIIG with a Stealth II-3 in my 2002 Ford F-150 pickup. The vehicle is a 4x4 with a 5.4L engine. The antenna performs well and tunes well.

The only problem is that I have an S9+ ignition noise problem. The noise disappears when I disconnect the coax at the rig or antenna so it is radiated rather than conducted. In fact, I have "sniffed" around the vehicle with a portable shortwave receiver and the noise appears to be radiating from all metal surfaces and body panels and I could not locate anywhere the noise seems to be the strongest.

The noise is at it's worst on the 20 meter band, non existant on 40, and tolerable on 15 and up. (perhaps the vehicle itself is resonant at 20 meters?). Of course, 20 meters is the band I was planning to use the most!

I have installed 1" wide braided ground straps from the pickup bed (4), body (2), and tail pipe (3) to the frame without any effect. I plan to install additional grounding from the engine block to the frame. I have checked with the manufacturer and learned that supressor plugs and supression capacitors are standard equipment on this vehicle.

I am new to HF mobile, and would appreciate hearing from anyone who has had a similar problem or anyone with suggestions.

Other than the noise, the Stealth II-3 works excellent with S9++ reports and comments like "I can't believe you are mobile". I am using an AM-Com controller that tunes erratically (RF?) but that is a problem I think I can fix once I purchase more torroid cores to decouple the control and power lines.

Thanks for your help and advice.

Bill, K8BI

Posts: 27


« Reply #1 on: January 30, 2002, 03:28:01 PM »

It seems like you are doing a lot one attempting noise suppression can do.

How do you have rig sourced for power?
1.) direct from battery?
2.) cigarette lighter plug

Choose #1.  Use the heaviest gauge you can get you hands on.  Fuse and Run both (+) and (-). Sheild it if necessary.  Some use tin foil-like aluminum wrap (industrial). Others use Belden #??? 1 1/2 braid as a sleave for both power cords. Some do the same for each spark plug wire.

Is the rig grounded to the frame of the vehicle?  Do everything short of welding it to the frame.  Seat bolts are usually connected to the frame.  Exploit one.

Where is the fuel pump? Is it submersible?  Near the tank?  ...near the antenna?  Is their anyway to shield it?  Is there an armor cover over it for protection. (Mine is behind the driver side rear wheel.). Strap that in as well.

These are just a few tricks.  I would suggest continuing to read all you can. ARRL has wonderful material on this sort of stuff.  Additionally, I wrote ARRL an email explaining my problems. They happend to have a point of contact at the GM ECM department.  Amazingly enough,  2 days later.... I was in a conference call with a group of engineers that used a vehicle just like mine to attempt to produce the same result.  ARRL ($34) dues that year went a long way.  I am saving up for a Life membership.  SOLD!

Any of three versions: Don Johnson's 25, 35, or 45 Years Mobileering Series are definately recommended.  He invented the DK3 screwdriver antenna.  He has a cult following ... hi hi hi.

Don't give up or get frustrated. Keep asking questions.  You'll get it. Mobile HF is a new, old beast gaining popularity with more and more CC&R victims.  It's getting easier,  believe me.

Auf Weiderhern 17m,
73, John de KB3CDF

Posts: 8

« Reply #2 on: February 13, 2002, 02:27:54 PM »

I don't recall seeing it in your post, but is your antenna grounded? Sometimes this can cause noise. Check the resistance on it, if it's too high, that might be it!

Posts: 3

« Reply #3 on: February 20, 2002, 09:36:51 PM »

these wires work great

Posts: 1

« Reply #4 on: February 26, 2002, 08:39:15 PM »

Hello all,

My employer has a mobile radio fleet that numbers over 4000 units. I work in radio communications, and often encounter and solve various mobile RFI problems. I have recently added a section to my technical topics and projects web site titled "RFI Solutions". Here I share what I have learned. While some vehicles presented are probably not used by many hams, some common domestic trucks and cars are shown and the specific RFI solution is outlined. The ARRL has just added a link from their TIS web site to my RFI page.

The specific 2002 Ford F-150 mentioned in this prior posting is not yet included on my site, but I'm sure I will test this vehicle in the future. All new vehicle types are tested by me for RFI compliance.

Check out   (from the home page, just select RFI Solutions).


Bill, K8CU  

Posts: 39


« Reply #5 on: March 21, 2002, 02:17:04 AM »

Might want to check with your local Motorola Dealer/Service agent. Motorola has had LONG a problem with ALL Ford vehicles and ignition noise. They have a filter assembly that mate with all their radios and eliminates the RFI problems 100%. The problem is in the Ford's electronic ignition system it seems to radiate at all frequencies, and is not very well sheilded to prevent this.

If I can find the Motorola part number I will pass it along...

Good luck
Jeff K8JSL
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