CB Radio Talk

forgive grammar. typing one handed. magnum S6, ive tried my tram 1140 on trunk lip mount on my hood, ive tried francis mounted to headache rack, ive tried Wilson 2000 trucker on headach rack. all give tremendous engine noise. I use 1000 magnet on roof, noise all but goes away. power on 8ga to battery, ground on 8ga to frame. cb shop says my headache rack mount is well grounded he checked with his fancy device. using 8x coax. why cant I use the better antennas mounted instead of magnet to get rid of noise. I am at a loss. any suggestions would be appreciated. truck is a ram 3500.
thanks

Hello dguillory 1,
Welcome to the forum. First thing I need to ask is was all the antennas SWR adjusted and then you still had a high noise level? How was the coax ran on the other antennas and did you try a different coax on each antenna. The possibilities are endless here, the Dodge or Ram 3500 is noisy, the lifters, injectors, fuel management system and fuel pump are nefarious.
As a new member could you post a intro in the "Welcome to the Forum" topic, [Please login or register to view this link] , so other members can say "hello",
3's

Greg

dguillory 1 wrote:forgive grammar. typing one handed. magnum S6, ive tried my tram 1140 on trunk lip mount on my hood, ive tried francis mounted to headache rack, ive tried Wilson 2000 trucker on headach rack. all give tremendous engine noise. I use 1000 magnet on roof, noise all but goes away. power on 8ga to battery, ground on 8ga to frame. cb shop says my headache rack mount is well grounded he checked with his fancy device. using 8x coax. why cant I use the better antennas mounted instead of magnet to get rid of noise. I am at a loss. any suggestions would be appreciated. truck is a ram 3500.
thanks

Welcome to the forum.

First things first...the most likely reason you haven't had any luck with a hard mount is the counterpoise (aka 'ground') connection for the antenna. The mag mount uses capacitive coupling for the counterpoise connection unlike a hard mount. I noticed you didn't mention the SWR or antenna tuning which is a big clue this is the case. If the counterpoise isn't achieved properly you'll never be able to tune the antenna.

Trunk lip mounts won't work on our trucks...you need a fender mount and while you can use the body bolt(s) to mechanically hold the mount, they are nearly good enough to achieve the counterpoise connection. You need to add at least one (if not 2 or 3) self tapping stainless screws into the fender to achieve this. Every antenna needs tuning and especially with radios that have a little power (or running an amplifier) you want to make sure the antenna is tuned to 1.5:1 or less (especially using an amplifier). Even your mag mount will require this. Below is what a fender mount for the Dodge pick ups looks like. I can run any antenna I want from the 102" whip to 3' antenna if I want (and everything in between).

Next, run a separate ground lead from the battery to the radio. The battery acts like a capacitor and will help reduce the possibility of a ground loop. If you are using an aftermarket fuel pump (i.e. Fass, etc.) you'll need to do more to reduce the noise...but that has to be done at the fuel pump power leads. Do the rest and I'll walk you through how to address the fuel pump noise if it's there.

Good luck
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I use a meter to check all of these setups. tuned each antenna except francis and was able to achieve well below 1.5:1 swr. I have a fender bracket to try and also a through roof nmo mount for the tram. I can try them next. thank you for the help guys. no aftermarket pump btw.

should I move my radio ground from frame to battery or run another and if so, from ground on radio plug or to radio chassis?

dguillory 1 wrote:should I move my radio ground from frame to battery or run another and if so, from ground on radio plug or to radio chassis?

Yes, both power leads should be the same sized wire and run directly from the battery.

Okay on the OEM fuel pump. When you replace it (eventually) you will need to deal with the noise the pump creates, but it's not difficult. The Francis can't be tuned other than lengthening the base (adding a spring, quick disconnect, etc.). It's a linear loaded antenna is why.

I would steer clear of any NMO mounts for 11m (CB) as they just aren't strong enough to handle the weight of a good CB antenna. They are fine for VHF/UHF but for CB (or any HF for that matter) stick with the 3/8 x 24 stud assemblies at least on mounts. Roof mounted with a base loaded antenna perhaps...but they aren't going to give you any options of switching antennas at all.

Using a fender mount I would recommend the following stud assembly for the fender mount also. It's a nice flush set up and easier to connect the coax using ring connectors. Stay away from Firestik Firewire set ups...they aren't very good quality.

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Good luck.

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Nice! thank you much.

If the noise your hearing is engine noise (pitch go's up when you give it gas...like a whining sound) that's not that un-command of a problem...Best way to get rid of most/if not all/ of the whining noise is going to be to do some bonding (RF Grounding)

What's happening is your radio is picking up noise from either the fuel pump, or alternator, even windshield wiper motors can cause noise in the radio...If the noise go's away when you turn off the engine, then this is whats happening.

You will need some flat-ground strap and will need to run grounds off parts of the truck to the frame...Like a couple of grounds from the bed to the frame, run a ground strap from the doors to the door jam (with the door open, just use a short ground strap from the inside of the door to the door jam where the hinges are) The hood would need a ground strap to the firewall...Tail pipes to the frame (This is a biggie! Believe it or not, tail pipes can act like long antenna's running the length of your truck and broadcast RF signal into your radio)

This is not all that fun...But it works...I probably have a mile of ground strap ran under my Suburban, and I also don't have a bit of noise...Radio sounds the same whether the engine is running or not...Before doing some grounding, the noise was horrible.

I found that the browning/Tram 140/1140 on the roof with through mount is by far the best antenna yet. Thanks for all your help.