Engine noise picked up from antennas

#409429

Hello i have a CB in my truck and its picking up engine noise. But it seems to be picking it up from the antennas directly. Defiantly not from power/ground and i dont think from the mounts. the video explains it better than i can type it

I have a dual 3' Firestik Firefly antennas mounted on a toolbox. The antennas go to a switch so i can choose which antenna i want to use. I have one antenna tuned for lower channels (1-25) and the other tuned for higher channels (15-40). This lets me optimize for a channel but i can still use the other side if one gets damaged offroad. The toolbox is bolted to the bed which acts as a ground but i also have a ground wire to a mount going to the cab as a ground

The noise is defiantly proportionate to the engine. when i unscrew the antenna from the base, the noise stops. both sides do this. the switch does a great job isolating each side and does not seem to be the issue.

#409431

Toolboxs make lousy grounding for antennas period...Try running a ground strap from antenna mount to frame ("flat-strap" not round electrical wire)

Try running several ground straps off tail pipes to frame...pipes can act like antennas running the length of the vehicle.

Get a radio with NB feature...less expencive radios like the Cobra 19's, Uniden 505's 510's have little if any noise canceling features...(get what you pay for)

As for your way of mounting the antennas...make's no sense...

First off, 3' antennas for CB use is a waist of time and money...To get any kind of distance out of a CB you need at least a 5 to 6' antenna, plus taller antennas tune better, and have less problems (like noise)

2nd...I would scratch the whole tool box mounting idea and mount to the roof...some guys get good results mounting to the left rear quarter panel close to where the back tire is at...less reflect from cab...Me, mine is mounted behind the cab on a riser which puts the antenna roof-high, and it works for me, but you need to make sure the riser is well grounded.

As for running a co-phase or two antennas tuned for different "CB" channels on a pick-up is a waist of time...First, there's not enough spacing available on something like a pick-up to make it worth-wild (unless you have one mounted on the front bumper, and the other on the rear bumper...that would work! (just look dumber than a sack of rocks)

One 6' to 9' antenna placed in the center of the truck, as high as possible, is the only way to go...unless you just like posting problems on forums for others to tell you the same thing I just posted....

(from 2011 me and Bozo...Texas to Idaho-mobile to mobile)

#409433

Engine noise is either or both alternator and spark plugs plus wires, new vehicles have coil packs. Alternator noise is usually a whine, this is the rectifier, but worn contact in the stator causes the sparking noise. Worn plugs and wires make the noise you are hearing because the plug gap is wide or voltage is escaping the insulation, this goes for the coil packs in most cases.
Just because you remove the antenna doesn’t mean the noise still isn’t there, you are just eliminating the way it’s received.
Grounding (bonding) of body panels is important, look at the hood, usually there is a rubber seal around the edge, the hinges have a Teflon bearing also the locking mechanism, add a ground there first, and check the bed for a ground strap or 2.
I agree with JJD, those inexpensive radios aren’t designed for the real world, op to something a little better but use that one to cure the noises.
What about the wipers and heater/AC fan, get any noise from them? Search through the forum on cures for them or ask in another post.

3’s

Greg

#409434

Im using a Uniden PRO520XL. defiantly not the best thing in the world, but its compact. im in a standard cab truck with all my space utilized which is why i have it mounted behind the passenger seat. it does have ANL which does eliminate a good amount of the noise. but it seems to overfilter and then it wont pick up alot of signals that otherwise come in fine

i dont use the CB a whole lot, few times a year for offroad events or towing in convoy. usually within a 1/4 mile of each other, sometimes a few miles when im doing vehicle recovery of unknown postitions. range is not a major issue with me. from what im told my radio comes in very clear compared to alot of the others using CBs.

any longer antenna would probably be a big issue with the tight trails i drive through. ive broken 3 Firestiks from tight trails already even with the springs probably too weak for it. i do seem to pick up signal great from truckers far away. thats probably more of them having overpowered amps but ive recieve pretty good signals from truckers hundreds of miles away few states over.

i use a truckbed tent for camping that will not allow antennas in the middle. the roof... well lets say its not an option because its no longer magnetic or mountable.it had like 5 gallons of bondo on it. its on my list of things to have replaced. but the trails i go through would just brush it right off or brake it

i have a Midlands portable CB as a backup. only real downside of it is that the speaker is not loud enough to hear over my engine

i dont recall this originally having this much noise untill pretty recently. the last 2 trips i went on it i noticed it got pretty bad. i found and replaced the ignition capacitor on the engine which was broken but it did not help. i tried adding a noise filter on the power to the CB last night and did not help. thats when i diagnosed it to the antennas.

im going to try and unplug the alternator and see if it affects it. the engine uses EDIS ignition (coil pack with plug wires, no distriubtor). the wires and plugs might be worn but, about 2 years old but with harsh use.

i have 4g battery cable bolted to the cab. and 8g from cab to bed

if need be ill jsut have to accept the noise and keep the ANL on. and tuen it off when engine off

#409435

I like SSB so eliminating as much noise as possible was my goal. Heavy gauge wire is okay but RF likes flat surface, braided straps can be gotten at auto parts stores, eBay, or Amazon. Do try the hood bonding, it may help. I personally don’t care for FireStik brand, Francis or Everhardt are better in my opinion for fiberglass antennas and in your mounting location, a top or center loaded antenna would be better. I ran a Hustler center load on my old van in the center of the roof, it took a beating, now use a 102” whip on the back bed corner of my pickup, local drivers call me “Tree Trimmer”.

3’s

Greg

#409444

this will be easy to try,

try clipping on a short, direct ground wire to the coax outer connector(ground) at the radio,

let us know what that does

and what is that larger black box under the CB?

CB Radio Talk

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