new amp and antenna install

[dilligaf]

Hi all, Ive just fitted a new predator 10k and amplifier into my mitsubishi shogun and have a couple of issues to resolve,,,, Firstly i have quite a lot of noise when i have the engine running probably s4 of crackling (not alternator whine) Secondly when i have the amp EAST..... 1x4 cranked up the wipers on the car come on even with the ignition switched off ???? The amp is located under the passenger seat, power for amp and radio are seperate direct from battery heavy duty cable with 80 amp fuses inline at battery, I have the swr set at 1.8 and am just waiting for delivery of a new shaft that will take the coils above the roof and resolve the swr problem,,, The amp and radio are grounded to the seat securing bolts, (one on each seat). any advice gladly appreciated, cheers steve

['Doc]

Sounds like you are getting RF into the Shogun's electrical system, which is a real PITA. (Had a Nissan that the left blinker and oil light would come on. ) I'd say start on the usual things, by-passing, shielding, and filtering. That'll be fun! No idea where your Shogun's computer is, but staying as far away from that thing is a VERY good idea.
Good luck.
- 'Doc


I can think of three other solutions;
1. A five gallon bucket of torroids.
2. Paint everything pink.
3. Midget naked hula dancer painted blue to dance around the Shogun when the interference occurs. (Please take pictures!) ... On second thought, I don't wanna see that.

[Hawk1]

Shielding and three (3 feet ) away from any other electronics at install is necessary for this setup. Additional check of grounding strap's and/or strap at install will deplete interference. Battery connect with fuse grounding connect will eliminate noise. Alternate will be in-line alternator noise/ground suppressor. Under seat install won't shield noise or electrical absorption at connection's at this mounting lower level. AMP power install effects even house's through it's stereo input device's. Do you think that with your current close proximity install that it wouldn't affect your wiring harness? Suggestion; go to a reputable electrical center. Then you'll be sure!

[dilligaf]

thanks for the replys, would i be better running the earth directly back to the battery? or clean up the seat securing bolts, the antenna is on the tailgate,however i have tried a seperate earth and the swr stayed the same,,,, i hope when the new shaft for the antenna comes it will bring the swr down, i dont think there are any companies in the uk that would be interested in helping with my install..... so its one step at a time here,,,

['Doc]

A different way of 'earthing' isn't going to make any significant difference. The problem is that there is just too much 'stray' RF floating around near things it shouldn't be near. The 'trick' is to keep that RF out of things is shouldn't be getting into. That's typically done by shielding, by-passing it to ground/earth, or by selective 'filtering'. Not being familiar with your vehicle and it's electrical system, all I can say is good luck!
- 'Doc

[yMidnite]

Could bad coax cause any of this? I am sure that if it could Doc would have said something (unless it just got passed him.)

[Radio 75]

Gotta disagree with Doc on this one.
If you are not using the same gauge wire directly back to the battery for ground as you are for power then you need to do so. Make sure your ground on your antenna is the best it can be as well. The 4 S units of static is constant when the vehicle is running?
There is just so much electrical stuff in autos now a days that it's hard to guess what is causing that.
Fuel pump maybe?

[drdx]

Throw a counterpoise wire on the case of the amp. Simply put, take 9 feet of insulated wire, taped at one end, connected to the amp case at the other. It will provide an RF outlet, basically a tuned ground, commonly used in the ham world on difficult ground situations like 2nd story shacks, and possibly reduce what your vehicle is having to soak up in the RF department. It is cheap to try and if it works, just route the wire beind the trim and out of the way.

-drdx

['Doc]

Can the feed line be -part- of the problem? Sure, it -could- be, but I honestly doubt it if it's of at least 'average' quality. Would changing that feed line 'cure' it? No, it won't 'cure' it. It might help, but I doubt it.
Size of the ground or (-) line. It should be capable of handling the same current as the (+) line. I can't think of any particular benefit of running a separate line if the metal used for that grounding/earthing, such as the metal body or framework of that vehicle. If that body/frame can't handle as much as the (+) line (if not more), then that's an awful 'skimpy' body/frame! Those power lines are also another avenue of 'entry' for interference. If eliminating one of them doesn't cause any particular problem, then why not? That sort of problem is not as common as you might think it is.
There are limits with everything, the amount of possible power output is one of them. Some things (electrical systems) are just more susceptible than others, so will require more work to 'fix' than others. That's normal.
- 'Doc

[Sheriff Bart]

I would move the amp away from the front entirely. If it's not wired so already I'd have a tech wire a remote for it and put that amp in the cargo area, trunk or what have you. (I'm not familiar with the Shogun). I would feed my power lines into the car on the side opposite where the computer is located and use the same gauge wire.
If the amp has 4 transistors I'd go with 8 gauge if the amp is smaller I'd still go with 8 gauge, but YMMV

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