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   Home   Help Search  
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Author Topic: 7.3 Truck Guys  (Read 1278 times)
W4AKF
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Posts: 11




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« on: March 06, 2017, 05:36:44 AM »

I have two 7.3 trucks, one a 1999 F-350 4X4 and a 2000 F-250 2X4. Both react the same way to RF generated on the 40 meter band. The trucks will miss and run rough when trying to tune the antenna, or just transmitting. I Got a Tarheal at Hamvention this year and a Tunematic to control it. I relayed my problems with the trucks to the gentleman  at the Tarheal booth and he knew exactly what I was talking about.

He showed me a diagram of how to ground the truck panels, engine, muffler...ect.  I spent the whole day yesterday ground strapping everything in the truck. Used good straps and stainless self tappers and stainless washers, nuts bolts,copper lugs. I bonded everything I could under the hood also, ac compressor  to fender....fenders to battery...condenser...alternator..radiator ...basically anything metal and large I strapped and bonded to ground.

Was disappointed with the results, still has the RF problem messing with the Brain.

Anybody have this issue and a suggestion of a fix?

73  W4AKF Huh
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W8JX
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Posts: 10942




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« Reply #1 on: March 06, 2017, 05:49:02 AM »

Have you tried installing a filter choke on power leg feeding rig? Kenwood make one called the PG-3B that I have used on many installs for close to 30 years with good results. It not only limits noise coming into rig but is also blocks RF from feed down power feed and back into car.
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Ham since 1969....  Old School 20 WPM Extra
W4AKF
Member

Posts: 11




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« Reply #2 on: March 06, 2017, 06:28:34 AM »

Great Idea, will give that a shot today. I was doing some reading...and may have found the culprit. This is a 706 install. After finally obtaining an opc-581 separation cable and getting the little tarheal and tunematic installed this week, my install was sans the little screw that bonds the separation cable to the xmitter. I have now installed a screw, which as I did not realize before, grounds the cable to the head unit. This may make a difference, today will tell on 40 meters.

Thanks!  73 Grin

W4AKF
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KAPT4560
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Posts: 295




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« Reply #3 on: March 07, 2017, 02:30:06 PM »

 Agree with all that's been said. The hood to cowl ground strap (or 2) is very important as I believe that the hinge pivots are isolated by nylon bushings and a greasy latch is an iffy ground path.
 I upfitted Ford chassis for ambulance-duty. Wiring shielding and isolation from RF was an important consideration. Twisted-wire pairs work almost as good as coax.
 There was also a useful Chrysler TSB for installation of transmitting equipment that is fairly generic and applies to almost all vehicles:
 http://dodgeram.info/tsb/1998/08-16-98.htm
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W4AKF
Member

Posts: 11




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« Reply #4 on: March 08, 2017, 12:25:25 PM »

Well I bonded the hood today on both sides....as mentioned....no improvement ...on 40 meters truck just wants to die....I have a choke in transit now...hopefully that will help. The gentleman from tarheal told me what module it was messing with...some injector thingy....he said it will smoke them  Huh and they are expensive  lol 
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W4AKF
Member

Posts: 11




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« Reply #5 on: March 08, 2017, 03:14:29 PM »

Here is what I am working with








Great swr on all bands...but on 40 messes with the truck....

73

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W4AKF
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Posts: 11




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« Reply #6 on: March 08, 2017, 03:18:22 PM »

one more

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W8JX
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Posts: 10942




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« Reply #7 on: March 08, 2017, 03:56:20 PM »

Nice job but I would of placed it on passenger side. I did a bumper mount on my Suburban on drivers side on logic it would not hit limbs near edge of road but regretted it ever since. It hit every drive thru over hang when it is attached. Had I mounted it on other side it would not of been a issue.
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Ham since 1969....  Old School 20 WPM Extra
W4AKF
Member

Posts: 11




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« Reply #8 on: March 08, 2017, 04:08:12 PM »

my 144-440 is on the other side  lol.....no drive ins for me....but it does have the quick disconnect if I have to...

73
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W8JX
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« Reply #9 on: March 08, 2017, 04:12:11 PM »

my 144-440 is on the other side  lol.....no drive ins for me....but it does have the quick disconnect if I have to...

73

My bumper mount has a quick disconnect too but its a pain on a trip using drive thru's and HF.
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Ham since 1969....  Old School 20 WPM Extra
KAPT4560
Member

Posts: 295




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« Reply #10 on: March 09, 2017, 12:47:03 AM »

 Flat, woven ground straps work better at suppressing RFI than a ground wire with a round cross-section.
 http://www.hamradioschool.com/going-mobile-part-2-solving-rfi-problems/
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W4AKF
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Posts: 11




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« Reply #11 on: March 09, 2017, 04:15:12 AM »

Yes I have been reading that...I only used the round ground from the antenna to bed...everywhere else is ground strap....I used the round for aesthetic reasons...may add regular strap today also....from antenna mount to bed....

73
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WX9DX
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Posts: 76




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« Reply #12 on: March 09, 2017, 09:45:59 PM »

Did you look to see if the computer has a plastic box around it or a metal box and is the ground on the box good under the dash?
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W8JX
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Posts: 10942




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« Reply #13 on: March 10, 2017, 04:18:21 AM »

Did you look to see if the computer has a plastic box around it or a metal box and is the ground on the box good under the dash?

I would not be concerned about ECM mounting or its box type. It is not the issue and you do not want to mess with it. Tampering with it in anyway could void any emissions warranty it might have that generally extend well beyond normal warranties.
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Ham since 1969....  Old School 20 WPM Extra
KAPT4560
Member

Posts: 295




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« Reply #14 on: March 10, 2017, 04:19:18 AM »

 Wrapping the ECU in grounded foil might shield it from ambient RFI getting in that way, but RFI may be more likely coming in through the wiring harness.
 As far as sensors, a digital 'on-off' square waveform might be more RFI-proof than say a sine wave or analog signal.
 Of course on Google I came across many discussions on which vehicle choice would have a better chance of surviving an EMP strike.
 Chrysler released a TSB (and this general idea may apply to other manufacturers vehicles in similar conditions). Technical Service Bulletin # 18-16-96 was for '96 minivans that would act-up around radar or air traffic control facilities.
 Mopar offered a 'hardened' Crankshaft Position Sensor that cost 3x what the standard CPS cost. This was where the engineers felt that the RFI was entering the ECU. The new CPS body and signal pigtail had extra shielding.
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