STRAY RF

[rosman6119]

Ok I just bought a new Dodge Ram 1500 pick up and I hooked up my Stryker 955 and my xforce 4 pill amp now when I key the radio barefoot I have no problem at all but when I turn on the amp my GUAGES go haywire is there anything that can be done thanks for any help.

[1206FL]

Remove amp?? JK. All BS aside, the truck needs to have some bonding done. the exhaust, hood, fenders, and all body panels to frame. Also try some ferrite chokes at the antenna feedpoint.

[MDYoungblood]

That is a good point, what antenna are you using? If you tie strapped the leads to the trucks wiring harness move them away from it, coax too. Ferrite's on the feedlines usually help, won't hurt on the coax either. Add another ground strap (braid type) to the computer (right side firewall), that will help if the engine stumbles when keyed. Last but not least, turn the power driving the box down til it stops interfering with the truck's controls.

3's

Greg

[Deleted User 14541]

I'm going to lean towards an antenna issue. Ferrite or a choke at the feed point will help but depending on how and where the antenna is mounted that may not be enough. Give us all the details about the setup that you can. A lot of antenna installs are good enough for low power levels but have issues when you crank up the power.

[rosman6119]

Ok I am running a Wilson 5000 at the back of the cab roof it's a quad cab coax is ran down between bed and cab and up through the floor coming in behind the backseat under it and to the front , power wires are ran to battery through dash on drivers side and come out bottom center of dash and ground wire is attached to frame behind center of the dash on the bottom my mechanic said there was other stuff grounded there. I think that is part of my problem my last vehicle I ran the ground wire to the seat bolt and had no problems at all.

Hey..

Try changing your ground location and see what ya get.

Bombero

[Deleted User 14541]

A lot of people seem to have trouble with dodge trucks and RFI. That doesn't mean it can't be done. A mag mount isn't ideal but at least it's up on the roof where it belongs and not mounted to the bed rail.

A short wide strap from the amp case to the body might help. You can strip some old coax and flatten out the shield. A lot of RF can travel on the positive cable coming out of the amplifier but there is usually some caps and ferrite in the amp to help with this.

Then I would try some kind of CMC choke at the antenna first. You may make some improvement by bonding the cab to the bed but you have a decent size roof...that's a plus.

RF grounding and DC grounding are two different things. An RF ground needs to be as short as possible and a strap. A thin wide strap is more effective than heavy gauge wire. Surface area is what counts here. Bonding.

Some people have success running a long ground wire down to the frame but they don't realize what's happening. The long ground wire is acting more like a radial than a ground. It may cure the symptom but the antenna system isn't as efficient as it could be. A choke at the feed point will make the coax shield a higher impedance path and force more RF current to flow to the vehicle body like it should. A solid mount on the roof goes a long way but if you don't want to drill a hole that's out of the question.

Right now your 5000 works fine barefoot because the capacitive coupling of the mag mount is good enough for low power. When you turn on the heat there is more RF current looking for a return path.

A dirty radio will also cause more RFI with an amplifier. I'm not saying that's the case here but something to keep in mind. I can put a dirty radio in my mobile and it will cause RFI with the stereo and I can hear the transformers in the amps talking. Put my usual radio back in, see the same total power and have zero RFI.

[1206FL]

I changed out the stock coax and used ferrite chokes at the antenna feedpoint for my mag mount setup, but I only ran a 2 pill amp in it. Never had any stray RF issues though!! And that was with about 250-300 watts on SSB pep. Sirio pl145 mag mount and lmr240, ferrite chokes at feed point, can't remember how many, but want to say it was at least 6.
Also check to see if any moisture has accumulated under your magnet mount. If it has rained, snowed, been damp out, or anything that would cause moisture, it will make its way under that magnet mount, and I don't care how tight it is attached to the truck!! Trust me. Been there and done that. It won't create an issue so much with barefoot radio, but add the power and things will go haywire. Again, been here. So this is something else to check if you are using a magnet mounted antenna setup. This is JMHO. But you'd be surprised how water/moisture can work its way into areas we think are tight!! Have a good one and 543 made some excellent points as well!! Listen to what he says. He does know his stuff. As well as most others here. I'm no expert, just go by experiences with these setups. Again, hope you get it resolved and have s good day sir.

[MDYoungblood]

Big watts going into a magnet mount antenna is not the greatest as stated, the moisture under the mount is a good point. If it's a new antenna I won't go to the expense of buying a new mount and coax for it unless you see any damage to it, the 5000 comes with decent coax. Ground the case of the box (radio too) especially if it's not bolted down (bolted to metal), shortest strap possible (braided straps are best). Move the negative wire of the box (radio too, I'll hear an argument about this) to a close grounded bolt, seat bolt is probably the closest, use conductive anti-seize compound on the bolt. I like to keep the negative lead as short as possible on my electronics (ground loop comments?).
Add another strap to the computer under the hood. Look under the cab and bed, check the ground straps on them, you'll probably find they're are none there add as many as you want, (I have 4 under the bed, 1 on the tailgate, and 2 under the cab). The hood and doors on a Dodge (most other vehicles too) are not bonded (grounded) add a strap to them.

You can try one thing at a time or all, and I would start looking into a permanent mount antenna.

FYI, I have a 04, ran an 1x8 for years after doing all of the above, only difference is antenna, have a little amp now, didn't really need all that wattage.


3's

Greg

[rosman6119]

Thank you everyone for the help I will do this as soon as I get a chance and I will let everyone know how it goes.

[MDYoungblood]

I even changed the negative battery cable to a braided strap, forgot to mention that. You can find the straps locally, car and truck part stores have them, if you can wait a few days the internet (might even check out the sponsors) would be cheaper and have a variety of lengths/widths.

3's

Greg

[Deleted User 14541]

If you start adding bonding straps you will see the swr change and may have to retune the antenna as you go. This is good and means you're making progress. When the improvements stop I usually stop adding straps.

It is very important that the antenna mound make the best connection possible. In your case the larger the surface area of the mag mount to the roof the better. Some guys running an antenna mounted on a riser behind the cab have had luck running a flat wide strap under the 3rd brake light and fastening it to the roof support. You can make it look fairly clean with a thin wide piece of sheet copper or braid and even paint the part that's visible. I used to use a riser but never got into that. I installed a puck and it was the best thing I ever did.

The place to start bonding is at the antenna mount and work your way out. You wouldn't take the ground radials off of a base antenna and put them in the shack would you? Unfortunately we have to make compromises between looking good and working good. This is where an ugly old suburban is nice.

[rosman6119]

Ok I fixed the problem I changed the ground wires of the amp and radio I bolted them to the seat and added a braided ground strap from the amp to the seat bolt and everything is fine now. Thanks for all the help.