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eHam Forums => Mobile Ham => Topic started by: WK5H on September 07, 2010, 05:24:56 PM



Title: Nasty RFI in a ford pickup - any hope?
Post by: WK5H on September 07, 2010, 05:24:56 PM
I apologize first off if this is going in the wrong topic (there is an RFI topic, but, I didn't see much there discussed with mobile RFI); if this is in the wrong topic, would an admin kindly move it over to the correct one.

I have a company vehicle which is a 2002 F-150 supercab pickup with the 4.8L V8 (for what the latter is worth).  It also has an aluminum topper on the bed.

I have my Yaesu FT-450 connected directly to the battery.  I have coax running to the very back of the topper, and the antenna mount is directly on the top-drivers side of the rear of the topper.

I get really nasty RFI, more so when I have a hamstick resonant on the band I'm tuning, and it's especially pronounced on 20M.  The noise also changes pitch with the increase in engine RPMs, and is REALLY noticeable when you let off the accelerator.

The noise goes away when I disconnect the antenna from the radio, so, I'm assuming it's not coming in through the power leads.

I have checked and verified the following:

Topper is grounded to the bed (did this myself)
Bed is grounded to the frame (came like this)
Cab is grounded to the frame (came like this)
Front panels are grounded to the frame (came like this)
Battery is grounded to cab (came like this)
Muffler is grounded to the frame (did this myself)

The grounds that I have done myself, I used the braid from scrap coax, flattened over a pipe.

I have tried to ground the radio's (-) lead about 4 inches from the rear of the radio directly to the cab; no change in noise (even though I'm sure the RFI isn't coming in through the power leads).

I can put just the tip of the PL-259 into the radio's antenna connector, and the noise is there.  I can touch the shield of the PL-259 to the inner part of the radio's antenna connector, and the noise is there.  The only time I can make contact with the antenna and radio with no noise, is if I just touch the shield to the threads of the radio's antenna connector without the center conductor touching anything, and with that, there's no basically no antenna/reception at all...

I have pulled the wires from the alternator to where the truck's just running off the battery; no change in noise.

I have put 2 ferrite choke cores on the lead from the alternator to the battery; no change in noise.

I have put 2 ferrite choke cores on the coax right at the antenna connection; no change in noise.

The noise doesn't appear to be the fuel pump; it doesn't have any noise when you turn the key on; only when the vehicle is running.

Where next?  Or, are these vehicles just inherently "noisy" and this is as good as it's gonna be?

BTW, there is absolutely NO way to even have the radio on with the noise blanker off; it's nothing but noise.

It's become an extremely frustrating issue that's about to make me quit running my rig mobile when I can't hear less than S9 signals over the RFI.

Help?


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: KL2GN on September 07, 2010, 05:54:24 PM

Sorry to hear about your mobile noise issues....
A few questions...What type of mount are you using and how exactly do you have it mounted?
You said that you are using hamsticks? correct?

You say that the various pieces of the vehicle are grounded?  I have yet to see a factory vehicle that is appropriately "bonded" together.  How many places did you bond the topper to bed?  The bed to the frame? The frame to the cab? The cab to the frame? The hood to the frame?  The factory doesn't do a very good job of this.

What type of ferrites did you use? what mix? snap ons?

Be happy to help troubleshoot....need a little more info to get some thoughts.

73, Tim
KL2GN





Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: KE4DRN on September 07, 2010, 09:02:34 PM
hi Brian,

the fuel pump will run a few seconds to pressurize the system,
then will stop until the engine starts running.

not sure if your model had the Ford fix for the fuel pump.

take a look at this link http://radioproshop.com/fordrfi.htm

73 james


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: KL2GN on September 07, 2010, 10:27:23 PM

Brian -

I was just reading over your post again and wanted to ask - Can you describe the noise any better?
Is it a whine? hiss? pulsing noise?  single distinct pulse?  2 or more pulses?

The 2 worst I have dealt with helping friends track noisy mobile setups were traced to the injectors in one truck and the other was alternator noise due to a ground loop in a car.

73, Tim


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: K0BG on September 08, 2010, 06:54:04 AM
Putting ferrite beads on DC power leads won't do any noise suppression, period! You could use a brute force filter, but if that f cured a problem, then something else in the installation is amiss.

The noise is probably the fuel pump, as Ford didn't start putting filters on as standard equipment until 2003, and the trucks didn't get them until 2005. You can still have one installed, but the price isn't cheap! You can do just as well by installing a ferrite bead on the power lead to the pump. This will require you to extend the lead long enough to get at least 8 turns on the core. Also, the ground lead from the pump to the frame on most model PUs, it over 4 feet long. That needs to be shortened. There is a TSB on this, and you can down load it from the web. If you can't find it, have your dealer print one out for you.

Depending on the production code the 2002 that you have may be either coil packs and wires, of COP (coil over plug) units. If it is the latter, there's not much you can do. If it is the former, new plugs and wires, are in order.

If you go to my web site, and look under Noise ID, there is an example of fuel pump noise.

Lastly, if the noise continues for 3 to 5 seconds after you switch off the ignition, it's the fuel pump. It runs until the oil pressure falls in order to purge the vapor canister.


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: WK5H on September 08, 2010, 07:04:17 AM

Sorry to hear about your mobile noise issues....
A few questions...What type of mount are you using and how exactly do you have it mounted?
You said that you are using hamsticks? correct?

The mount was put on by the person who had the vehicle before me (company vehicle), and he also is a ham.  It's a mount that's typically used for a CB antenna; 4 bolts mounted vertically to the back of the topper.

I say they're hamsticks, but, they're actually the ones from MFJ; for example, the 20M stick is this one:
http://www.mfjenterprises.com/Product.php?productid=MFJ-1620T

You say that the various pieces of the vehicle are grounded?  I have yet to see a factory vehicle that is appropriately "bonded" together.  How many places did you bond the topper to bed?  The bed to the frame? The frame to the cab? The cab to the frame? The hood to the frame?  The factory doesn't do a very good job of this.

The topper is bolted about every 2 ft with bolts to the bed of the truck.
The bed has about a 6awg wire bolted from the bed to the frame on the passenger side.
The cab has a fairly large strap on the passenger side under the door that grounds it to the frame.
The hood has ground straps from the hood to the cab at each hinge.

What type of ferrites did you use? what mix? snap ons?

The ferrites I used were the snap-on type from Radio Shack.  The exact ones are here:http://www.radioshack.com/product/index.jsp?productId=2103222

Be happy to help troubleshoot....need a little more info to get some thoughts.

73, Tim
KL2GN

Many thanks!






Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: WK5H on September 08, 2010, 07:09:32 AM

Brian -

I was just reading over your post again and wanted to ask - Can you describe the noise any better?
Is it a whine? hiss? pulsing noise?  single distinct pulse?  2 or more pulses?

The 2 worst I have dealt with helping friends track noisy mobile setups were traced to the injectors in one truck and the other was alternator noise due to a ground loop in a car.

73, Tim

I'll get a recording of the noise today when I'm on the road, and put it up.  It's more of a whine/hiss.  I wouldn't say it's a pulse, unless it's a very very fast pulse.


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: WK5H on September 08, 2010, 07:11:48 AM
hi Brian,

the fuel pump will run a few seconds to pressurize the system,
then will stop until the engine starts running.

not sure if your model had the Ford fix for the fuel pump.

take a look at this link http://radioproshop.com/fordrfi.htm

73 james

I don't think it's the fuel pump; the sound files I've heard on the net that are described as fuel pumps don't sound much like the noises I'm having, but, I'll post up the noise that I'm having and maybe that will help.


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: WK5H on September 08, 2010, 07:13:55 AM
Depending on the production code the 2002 that you have may be either coil packs and wires, of COP (coil over plug) units. If it is the latter, there's not much you can do. If it is the former, new plugs and wires, are in order.

I do know for a fact that this vehicle has coil packs; one went out about a month ago, and had to be replaced.


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: K0BG on September 08, 2010, 09:21:09 AM
The ferrite beads from Radio Shack are all but worthless. They're an unknown mix, and a 6 turn core doesn't have any appreciable reactance until the frequency is over 100 MHz. The mix you want is Mix 31. The best price at the moment is from DX Engineering. A package of 5 of the 3/4 inch ID beads is $25 plus shipping. AES and HRO both sell them too. Remember the reactance is to the square of the turns, so a multiple turn bead is better than a bunch of one turn beads.

If it is a company vehicle, you're sort of stuck. As plugs age, their gap gets wider, which raises the voltage, and the RFI. Age also makes the wires leakier.

Post the noise someplace, and e-mail me the location. I'll let you know what I think it is.

Let's visit the fuel pump again. When you first turn on the ignition, the pump runs for about 3 to 5 seconds, and stops. Once the engine is running, the pump runs, but not continually. The percentage of run time is determined by the fuel needs of the engine. The cycle increases with engine speed, but not nearly at the rate the ignition RFI does. If it sounds like a hash which turns into a buzz at high RPM, then is probably ignition RFI. I have examples of both on my web site.



Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: WK5H on September 08, 2010, 03:03:36 PM
I got some decent video with audio of what the noise is; more of a crackling noise, from what my ears tell me.

This one is where I am parked in a parking lot, turn on the key for a few seconds, then start the truck a couple of times.
http://www.youtube.com/watch?v=vF7vIh2kP48

This one is where I'm going down the road, then come to a complete stop and turn off the engine.
http://www.youtube.com/watch?v=x3mhRXKUQC8

BTW, my radio does NOT look this bad; youtube's compression instantly made my radio look like I drug it through a caliche pit...  And the radio also doesn't shake around like the video shows...  My hand holding my iPhone, however...


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: KL2GN on September 09, 2010, 02:46:02 AM

Brian-

Thanks for the response and posting the video clips.
If you were driving a diesel I would say it was injector/ignition noise.....but since your not.
I thought I heard a little bit of hash at the beginning...sounded like fuel pump but the rest of it sounds like ignition noise to me.

I'm sure Alan will have some thoughts on it, he has helped troubleshoot way more of these then I have.

73,
Tim


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: WK5H on September 09, 2010, 08:06:27 PM
Alan has given me some tips, and as soon as I get a chance, and the afternoon rain showers quit, I'm going to put em into production.

As soon as I get em done, I'll report back to let everyone know the changes.

Thanks again to all!


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: K8KAS on September 17, 2010, 06:32:11 AM
The worst noise generator on Ford products is their fuel pump period. The first thing I would do is get a filter on the pumps wires at the tank, I think ARRL has a lot of info on what it looks like, I believe Ford Parts as well offers one for their TDOT program avbl thru the dealers. I built 2 or 3 of these a few years ago but can't remember the values I used, but I can tell you the difference they made was day and night. Ferrite beads from Rat Shack are worthless I agree, and if you do use 31 type or 43 type from a good source it takes lots of them like 15 or 20 to see any change, 1 or 2 are just a waste of time. 73 Have Fun Denny K8KAS


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: AA4PB on September 17, 2010, 09:32:20 AM
Sounds like typical ignition noise from the spark plugs to me. Once you get rid of that you might find some fuel pump hash at a lower level.

What happens if you remove the antenna from the mount and just leave the coax and mount connected? If it is greatly reduced then its an indication that the antenna itself is picking up the noise.


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: KG4PID on September 17, 2010, 08:28:17 PM
Be sure the radio has a good RF ground to the chassis of the truck. I'm working on a HF install in a Ford Freestyle. I had the antenna mounted and ran coax to a radio that was sitting on a small table about 20ft from the car and powered by a 20Ah gel cell for testing. When I started the car it sounded just like the noise in your video and was reading S9. I mounted the radio in the car and used a 1/2 inch ground strap about 5 inches long between the radio and the chassis. When I started the car almost all the noise was gone, YEA! I now have about an S2. This was today BTW. Hope your problem turns out to be this simple.

Max


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: K0BG on September 19, 2010, 06:56:07 AM
Ah! Here is a factoid for beginners: If grounding the chassis of the transceiver fixes, changes, reduces, or eliminates an apparent RFI problem(s), then something else in the installation was (is) amiss! Just about 99% of the time, it is a poor antenna and/or mounting.


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: WK5H on September 23, 2010, 03:09:13 PM
I've put a ground strap just about everywhere a ground strap can feasibly go; every corner of the aluminum topper to the bed, and every corner of the bed to the frame, from the cab to the frame, from the driver's side hood hinge to the body (passenger side is already done), etc. etc.

Still no relief on 20M, but, it did clear up a bit on the lower bands (40M and down).  Upper bands (17M and up) are still a little noisy.  20M is still just horrible, even with the NB on.

I bought a 10 pack of mix31 snap on ferrite beads, and put one on top of every coil-over plug wire, and no difference.

I took my kenwood HT (TH-F6A which has HF receive), a short piece of coax with about 3/4" of the tip exposed and "sniffed" around the engine compartment...  RFI is radiating from just about every wire under the hood, including the COP wires, injector wires, misc wiring harnesses around the compartment...

One thing I did notice...  The vehicle is VERY resonant around 20M.  I accidentally touched the tip to the aluminum topper, and 20M signals came in like gangbusters.  Thought it was the topper, but, touch to the bumper, and same thing.  Does this have anything/nothing to do with the issues I'm having?


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: VE3XKD on September 24, 2010, 04:05:48 PM
Hi

I had similar problems with the COP on my Toyota Prius. I carefully wrapped each COP wire and connector in 3M 1181 copper foil tape, and wraped each COP wire back to  the engine chassis as far as i could go. I tack soldered the 3M 1181 seams, and bonded each line to ground. Eventually i cured most fo the noise, and now have only about S2 to S3 to contend with. there is some info on Alan's web site about using 3M 1181. Oh yes, each COP line has as many ferrite beads on the line as i could physically place.

If you are not certain where the noise is coming from, I suggest you make a 1 inch loop probe out of RG 58 or 59, attach the probe to your HF radio, and start listening or probing for the sources of noise. Once you locate a noise source you can either bond it or add ferrites or cover it in 3M 1181 and shield it.



Good luck!


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: K1CJS on October 18, 2010, 05:49:56 AM
Just because it's not a diesel engine does not mean that injectors can't be causing the noise.  It does sound like the problem is the coil packs, but I would not cross off the fuel injectors from the list.

I have a Merc Grand Marquis that is as quiet as can be when using my HF rig, but I've been told that my case is the exception.


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: K0BG on October 18, 2010, 07:12:17 AM
Not really. The Ford COP units are very well designed. Internally, there is a spring which holds down the contact against the plug. It was designed to have a specific reactance. And, there is a chunk of ferrite as well. They are as quiet as any COP on the market, and better than most.


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: NY3V on October 18, 2010, 08:29:29 AM
My 1997 Ford Escort causes Tremendous hash when I plug my low power MFJ9420 12 watt SSB XCVR into the cigarette lighter jack.

The Surprise was when I used a regulated voltage adjustable switching power supply I bought to power my laptop from the cigarette lighter jack.

It has a slide switch that goes from 15VDC in steps to 24VDC.

I set it to 15VDC and was pleasantly surprised that it reduces the hash to manageable levels. I assume it is because it has a built in ferrite filter on the power cord coming out of the power supply.


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: K0BG on October 18, 2010, 09:41:08 AM
Well, would it surprise you to know that by raising the input voltage you reduced the RF sensitivity of the front end of the receiver?

Your 1997 Escort uses plug wires. Considering the age, I'd bet that replacing the plugs with new, properly gapped ones, and replacing the plug wires will reduce the noise by quite a bit.

It's a little difficult comparing wired ignition systems to COPs, because the mechanism which generates the impulses you hear is quite a bit different. You really can't bead the offending wiring, as by the time you get enough reactance to quiet things down, you will have integrated the signal enough to cause other problems like delayed ignition pulses.

In the near future, when all-in-one (injector, spark device, and piezo-knock sensor) become common place, we'll have a whole new set of problems to overcome.


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: W5WSS on October 28, 2010, 11:00:38 PM
I know this is late. I use an older Ford 3.0 litre 6 cyl. with fuel injection. I do not need any filtering with this install. I believe that most of the noise that emanates from the Electra/motor of this automobile is reasonably similar to most automotive vehicles. Having said that perhaps a large extent of your noise would be ignored at the antenna provided the mount is drilled and bolted through the car top and centered. The car body when properly connected to the feedline shielding AT the feed point of the mobile vertical antenna will then act as a Faraday shield and noise pickup will be reduced to it's minimum. The point I am making is that when the antenna is centered in this fashion it is blocking more of the noises that are generated and helping to prevent noise ingress in the first place so there are advantages in biting the bullet and drilling those nasty holes through the roof top of the ham operators vehicle. I know for a fact if I placed my antenna anywhere else around the carbody my noise would simply increase...and that is without attacking the noise at the source just by locating it in the best spot to begin with. 73


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: K0BG on October 29, 2010, 12:37:56 PM
Well, Robert, I wish it were that simple! It isn't!

A vehicle body is not a Faraday shield in the correct sense. Yes, high mounting does help the RFI noise situation, but not in the reasons you state. The whole key it to minimize ground losses, by making most of the RF current flow through the vehicle's superstructure, rather than the lossy surface under the vehicle. Proper mounting helps, and does height if the added height mounting scheme doesn't add more ground loss (mounting atop a long stalk for example).

Probably the most effective thing you can do to reduce RFI beside good mounting, is to bond all of the horizontal surfaces like the hood, trunk, and the exhaust system. Do it right, and top of fender or quarter panel works just as well as roof mounting. Maybe better, it is allows a longer overall length. Remember, radiation resistance is a square factor of electrical length.


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: K1CJS on November 08, 2010, 09:40:07 AM
BTW, my Grand Marquis isn't one with the COP design--it also has wires with 2 dual spark packs, one on either side of the front of the engine.  It also has individual cylinder fuel injection.  The plug wires have been replaced with original equipment Motorcraft wires a couple of years ago along with the plugs.  That is possibly the main reason I have no noticeable RFI in my car except for a tiny bit of whine--that I ignore.


Title: RE: Nasty RFI in a ford pickup - any hope?
Post by: K8KAS on November 09, 2010, 08:59:43 AM
I have never seen a Ford product without a fuel pump noise problem, yes Ford does have a fix called
the "TDOT fuel pump noise filter" required by all Fords sold to the Texas Dept of Trans. You can also
see ARRL RFI/EMC Handbook for a filter design/simple and works great for the fuel pump motor. I have seen a number of pump filters in QST and other rags. When I install at the pump the simple filters mentioned usually 90% of the vehicle noise is gone period.  Denny K8KAS 73