RFI Problems

Discussion in 'Mobile Radio Systems' started by WB0SND, Jul 31, 2019.

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  1. WB0SND

    WB0SND XML Subscriber QRZ Page

    Well, I just installed a Yaesu FT-857D into my 2016 Toyota Tacoma Pickup. I have horrendous RF hash from what I think is the fuel pump. It is a constant S-9 on 20 and 40. As recommended at K0BG website and elsewhere, I just bonded the exhaust system in 4 places and bonded the hood. I used 1 inch wide Belden braided straps. I know I need to bond more parts of the truck, but after the exhaust and hood, I note absolutely zero improvement in the noise level. Shouldn't I see at least some improvement? Am I just wasting my time? Any pointers are welcome...... 73 Mike WB0SND
     
  2. WB0SND

    WB0SND XML Subscriber QRZ Page

    I guess I should have elaborated on my install a little more. The antenna is mounted on the trailer hitch. At the moment, it's my only choice. The antenna is an older High Sierra. I ran a ground strap from the antenna ground side down along the mount where at the base of the hitch mount, There is a ground connection. At that point the ground strap continues to underneath the truck near the bumper where the strap is grounded to the frame of the truck. I should add that the antenna seems to tune well.

    I'm pretty sure it's the fuel pump making the noise because when I put the key into the ignition (before starting it), the noise comes on for a second and then stops. Then, when the truck is running, the noise is constant. When I shut down the truck, the noise lingers for a second or 2 and then stops. Again, the noise is kind of a white noise hash rather than ignition noise. I did have some ignition noise as well, but I think there was an improvement in that.

    Also, I think the fuel pump is in the gas tank And the gas tank is plastic......
     
  3. K6CLS

    K6CLS Ham Member QRZ Page

    well, if you just want to operate portable, but not while mobile, install a second battery for the rig to use while parked. Charge it off the truck's alternator. Consider installing a buck booster too, most HF rigs are a lot happier at 13.8v than 12.1v.

    Personally, I find HF operating too difficult to do while driving. my two vehicles have a lot of noise and birdies while running, so mobile operating is difficult anyways.
     
    NH7RO likes this.
  4. WB0SND

    WB0SND XML Subscriber QRZ Page

    Thanks, but I do want to operate while in motion. I operate primarily CW.
     
  5. KF5LJW

    KF5LJW Ham Member QRZ Page

    Doubtful bonding has much to do with it as you have discovered. Just based on the type of interference you described suggest installation issue or issues. I would bet the noise is being induced on wiring vs picking up noise on antenna.

    Some points to check.

    1. Negative DC Battery return terminated to nearest chassis hard point like seat bolts. If you look carefully under seats, near door under the carpet, kick panels under dash, dash mounting points you can find ground terminals. Keep the radio negative wire short as practical and away from vehicle wiring. Do not put a fuse in the negative conductor.

    2. Route radio Positive Supply isolated from vehicle wiring to the extent possible. Where they must coexist in same space cross at 90 degree angle. Do not run tightly coupled to any vehicle wiring. Keep as much distance as you can. Look at your battery terminal closely. I think Toyota has an open Terminal for auxiliary equipment like radios or a wench. Terminate battery positive with in-line fuse.

    3. Treat all other radio wires, cable, and coax as described above. Keep it away from vehicle wiring to the extent possible.

    My educated guess is you have some coupling issues into the wiring, or improper power wiring.
     
  6. KF5LJW

    KF5LJW Ham Member QRZ Page

    I hope you are joking. CW while driving?
     
  7. WB0SND

    WB0SND XML Subscriber QRZ Page

    I suspect you are correct and I’ll look into those things.

    Sure lots op people operate CW mobile. Just put paddles on the passenger seat and send. Yes i am driving one handed while sending. No different than holding a mic. Receive is just in my head.
     
  8. K0BG

    K0BG Platinum Subscriber Platinum Subscriber QRZ Page

    I seriously doubt it is the fuel pump itself. It may be the purge canister pump, but it shouldn't be running once everything warms up. It could also be the B-CAN system, but since I haven't heard what it sounds like, it is just a guess.

    As for the wiring... Cross induction of RFI is very rare, and almost nonexistent if you wire properly. It can happen with respect to common mode RF, but that is the reason to used control line chokes.
     
    K0UO likes this.
  9. WB0SND

    WB0SND XML Subscriber QRZ Page

    Well the 12 volt line comes into the cab on the driver’s side and runs under the sill plates to the back of the cab where the radio sits behind the back seat. Yes the 12 volt line runs alongside some of the wiring. So, as suggested maybe I need to change the routing. Maybe I should have the radio up front?

    It was only a guess that noise generator was the fuel pump. I’m really not familiar with the modern systems.

    I guess I am just not sure where to go from here. I guess some chokes? You mentioned control line chokes. But I am not sure what control line? One of the control lines in the truck?

    I don’t think the noise is computer noise. There are no squeaks and squawks, just a continuous white noise. It does have the characteristic behavior of starting for a second or 2 and then quitting when switching the ignition switch on without starting. Sorry to sound unsure and ignorant. But I am unsure and ignorant
     
  10. W5LZ

    W5LZ Ham Member QRZ Page

    Computer noises can certainly be a "buzz" rather than a "modulated" sound. It sounds likes 'normal' situation with a late model car. Sounds silly but try rapping that computer in foil (what you can get to anyway. If the noise starts when you put the key in, then it has to be something in the electrical system. Now all you gotta do is find the d@&& thing..
     

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