I recently purchased a 2015 Ford SuperDuty with a 6.7L Powerstroke diesel. The day after I picked up the truck I headed to AR and SC to visit family but also operate in those state's QSO parties. I installed my Scorpion SA-680 on the bottom part of my 5th wheel hitch and ran the coax and antenna control cables from the bed through the back doors. The only grounding I had time to do was a strap from the bed to the cab. I quickly found the fuel injectors are apparently tuned to 20m as the RFI into my Elecraft K3 was terrible. Amazingly all the other bands are fairly quiet.

During the QSO parties I relied on the K3 noise blanker to knock some of the noise down on 20m. I returned from SC just a couple of days before the Texas QSO Party. During that time I grounded the exhaust pipe in a couple of places but that didn't have any impact at all. I also grounded the other side between the bed and cab. I again relied on the K3 NB during the TQP but the noise was just terrible.

After the TQP I decided to order some ferrite cores to see if they would help any. There is a 1" diameter bundle of wires coming from the Powertrain Control Module (PCM) that I think contains the controls to the injectors. So I ordered two 1" mix 31 split ferrite cores from Mouser.com, PN 623-0431177081 (Fair-Rite PN 0431177081). I also ordered four 3/4" mix 31 split cores, PN 623-0431176451 (Fair-Rite PN 0431176451). I already had some 1/2" mix 31 split cores.

I installed the two 1" split cores on the center bundle of wires coming from the PCM and checked the noise. It was reduced somewhat but still there. I installed a 3/4" and a couple of 1/2" split cores on some split outs from that cable. Those seemed to help too but still noisy.

I have a handheld Icom IC-R10 receiver so I set it on 20m and started sniffing around. I found LOTS of injector noise on the driver's side battery negative cable. While listening to the receiver I touched a ground strap from the battery negative terminal to a nearby bolt. The noise disappeared! I made up a strap and installed it from the battery negative terminal to a bolt located on a cross member. Checking the K3 the injector noise was gone!

Wondering if I really needed those expensive ($20 each!) 1" split cores I removed them and checked the K3. The injector noise was back. Between the split cores and grounding the negative terminal on the driver side battery the injector noise has disappeared. Success!

Listening to the K3 when I turn off the engine I can hear a slight drop in background noise. I may try to track down that noise but the main problem has been fixed.

No comments

The author does not allow comments to this entry