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Satellite Radio Antennea under hood?

Discussion in 'Audio' started by 73k5blazer, Jan 20, 2007.

  1. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    Well, I'm looking for a decent place to mount my Sat. radio antennae, well I
    ran some tests
    and I can place it anywhere under a fiberglass surface.

    I could put it on the rollcage, but a much cleaner more inconspicuous location would be under my fiberglass hood up front somewhere.

    So, anyone see any issues mounting the antennae under the hood? Heat issues?
     
  2. lak2004

    lak2004 1/2 ton status

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    Only thing I have seen a problem on is Heeps, we mount them right behind the hood on the outside and the wire goes through the firewall which has caused static and motornoise when using the FM modulator. But I havent seen any problems with heat on the wire itself.
     
  3. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    Fiberglass firewall as well, they way things are now, I can put it in with the temperature probe (I have a Gentex Mirror with Outside temp reading) wires that pass thru the firewall in it's own hole, far away from any other power wires, but then it would pick up into the main clip harness going out towards the front which has elec. fans, headlights, off-road lights, horn, turn sigs, park lamps power and ground in that harness. (My whole wire system I wired from scratch, very custom harness)

    I never thought about an interference problem with the signal running the wire antennae wire with power wires. Is that something I need to, umm, worry about?
     
  4. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    Well, I hooked er up, run the ant. into the motor compartment way up front and high, integrating the wire into my main clip harness up there.

    For fun I turned it on, keep in mind my truck is in my nice heated garage. Low and behold, I had 4 out of 10 bars, in the garage with the hood down. :cool: No, there is no terrestrial signal around here, my radio has seperate sat/ter signal meters, and confirmed, no ter signal. All sky. I dunno :dunno: what sky, but the signal is there. :D

    So I turn on the lights, off-road lights, signals, hazzards, brakes, try all the elec. accessories, doesn't seem to bother the signal or the quality of the music at all. Albeit, I've not motor yet, so that might change things.

    I think I'll try it in the engine compartment there.
     
  5. lak2004

    lak2004 1/2 ton status

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    I dont think you should have a problem. Now you got me thinking about where to put mine. I have been slacking off on doing it because I dont want to put it on the dash and so far cant think of anything else too great.
     
  6. chevyin

    chevyin 1/2 ton status

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    Motor noise (usually called alternator whine) is almost always cause by ground problems (corrosion, ground loops, etc) not by running the antenna wire in, near or through a firewall (metal or otherwise).

    I really doubt any wire you might be running through your dash harness will carry enough current to cause any concern over induced noise.

    Under the hood should work fine, assuming you used common sense when mounting it (stay away from headers etc). Glad it sounds like its gonna work out for you.
     
  7. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    Shouldn't be any ground problems here. I have run all my ground back to a protected ground block with a dedicated out back to battery. I know what shaky grounds do to an electircal system. No fun chasing those problems. Nothing on my K5 is grounded to frame.

    I've calclated various circuits to see if a potential ground loop could be created, and according to my calculations, there shouldb't be any issues.

    But, we'll see if it all works outonce I get her on the road.

    Thanks for all the input!
     
  8. chevyin

    chevyin 1/2 ton status

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    Why did you decide to bypass the frame? They make very good conductors, lots of metal. Usually people dont run a dedicated ground wire back to the battery unless they have a uni-body vehicle and are worried about resistance issues... or if they purchase JL Audio equipment. heh

    Im sure your system works great, just curious why you went that route.
     
  9. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    Frame connections are too much subjected to corrosion and other bad influences that reduce the integrety of the connection, and increase resistance.
    It's not just my stereo, it's everything, literally. Since I have a fiberglass body, I had to set up these ground blocks anyway for alot of stuff. My biggest motivation, aside from creating ground loops for things like brake controllers, frame and body grounds are the cause from the majority of problems caused on many vehicles I own. Light getting dim? Brake light flicker? Trailer lights don't work? Usally a bad ground somewhere.

    The frame itself is grounded via a ground strap, but all electrical accessories are grounded back to battery directly. Winch, amps, inverter, almost a must to bypass frame, you couldn't get enough metal contact, and over time it would get even worse as it corrodes. That's why Warn, and amp installation kits, usally specify a dedicated ground back to battery.

    Remember too, electrical current runs only on the surface of a piece of wire. The more strands, the better the conductor. Frame is low strand, but heavy. Capable of carrying alot of current, but getting on and off it is more the problem. Plus, the high tensile stenght steel used in most frames, is somewhat incomatible, eletrically, with other metals used in electrical terminals. As voltage streams across the incompatible metals where they meat,it creates more corrosion.

    More strands also help when making connections,more wire to contact other surfaces of the thing your crimping/soldering etc.

    Paranoid, perhaps,but I live in the rust belt. For the high amperage stuff, avoiding the frame is always a good thing, for the 5-10-15 amp stuff, it's more just a logevity and realiabilty issue.
     
  10. chevyin

    chevyin 1/2 ton status

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    Thanks for the reply. :)

    I didn't realize it was an entire fiberglass body, that makes more sense.

    For larger wire connections, I always solder (as should anyone), strands really dont matter in that case. I do however chose high strand wire for its flexibility, many times a must in automotive installs. Welding cable works well, and is much cheaper than commercial 'audio wire'.

    I need to check further into the wire strand issue. I may be wrong, but so far as I know wire must comply with awg standards, no matter what the strand count. For example, fine stranded wire will have a slightly larger diameter than solid core.

    Considering you are running a custom fiberglass rig, your setup makes perfect sense. Thanks for the explanation.
     
  11. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    The thing with the strands is more of a quality and heat issue. The more strands, the less ohms/foot you'll have and the less heat you'll have. This comes into play over long distances. More strands also means easier to terminate and your termination will have less resistance becasue solder and crimpes more easily catch many strands rather than a point load contact from a crimp on a single strand wire.

    A single strand wire can have the same AWG rating as a mutli-strand wire, but will have more heat and more resistance. At 120v, like in a house, it's not so bad if you drop a few volts over distance, single strand is much cheaper to manufacture, and that's why it's used more in that application. At 12v, it makes a huge difference if you put 50amps in a wire over 25feet (approx distance from battery to back of K5, run nice and neatly), you'll see 1-2volt drop with the average cable out there, try running your audio amps at 10-11 volts, they won't like it very much.

    There's all kinds of wire out there, I toke most of my input for the electrical system from a friend of mine who's a EE for Delphi (Automotive group). Back a few years ago, this company in the suite next to us was moving out and they were throwing away and bunch of leftover crap and I saw this 50'+ foot spool of wire in the trash bin. I swiped it. Turned out to be some goofy locomotive cable, extremely high strand count 2awg, but the lowest ohm/foot my EE buddy had ever seen. I looked up a price on it, it's over $100/foot :eek1:. I used this wire for my main feed to the back for winches and the 2 polk amplifiers back there, as well as the 500w inverter back there. The 2ga is terminated into the winch terminals along with 6ga out to each amplifier back there and 6ga for the 500w inverter.

    I did ALOT of research about voltage drop, heat, resistance, distance and loads back in early 2006 when I was designing the whole electrical system for the K5.
    Digging up a few notes (The locomotive cable is the RayChem wire, Vd is Voltage Drop, Vs is starting voltage, i can't find the formula I used, but there's many out there, alot make assumptions about wire size, but if you have the spec of the wire (number of strands and size of strand), it's better to use that, much more accurate)
    According to my calculations, using the specifications of the Raychem
    cable, I'll be looking at a 2.18%Vd (150amp load, 13.5Vs, 20' length) .
    Which is much better then most 2ga cable out there that I can find. The
    stuff I probably would have bought, SAE J1127 spec battery wire ends up at
    4.25%Vd over 20', at 150amp load starting at 13.5v.
    Again, I doubt I'll ever pull 150amps continously, I guess it all comes
    down to how much will I pull continuously. The raychem wire does good at
    high temps too, it's performance doesn't start dropping significantly
    until 180c, (limit of 220c), where most SAE battery wire drops off fast
    above 40-60c.
    At my guessing of an average load, say 65amps Vd w/the raychem 2ga becomes 1.85% where the J1127 wire is 2.84%. Vd goes much higher if your Vs is 12v as opposed to 13.5v. I better get a good battery and a good alternator that puts out decent amps at idle!

    The 65 amps figure is average load I guess running the 2 audio amplifiers I have and the 500w inverter. Most of the time the inverter will probably not be used, so you could probably take that off there.

    Temperature is a big thing too. If you run those wires in the engine compartment or near exhaust, your voltage drop will rise rapidly with a low-strand count wire.

    Overkill probably, but better to be more robust here than to have the electrical system fail me at some point. I never even accounted for duty cycle. I assumed 100%, which is almost unheard of. The audio amps, while rated at 350w and 500w respectivly, will not pull that continously. You can overload a wire temporarily too, OEM's do it all the time. Look at the puny 16ga wire they use for your wiper circuit. urn those on on a 10degree day with some snow load on there and that motor will well exceed the 22 amps the 16ga can take 100% of the time. But after a few wipes, the load drops or the circuit breaker will blow. Look under the hood of a new car these days, there's alot more auto-reset circuit breakers than there used to be, so OEM's can run smaller wire (saving $$$) and still be safe about it.

    Anyhow, I think I got off the original point here, which is, not all 2awg wire is created equal. There are differences, huge differences.
     
  12. chevyin

    chevyin 1/2 ton status

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    I think you are making some generalizations there. First off, if we are going to compare solid core to multi stranded wire, it should be noted that for fine stranded wire with very little air gaps between the strands within the braid (common in 'audio' power cable) it will react extremely similar to solid core wire. In any real world application (especially audio) you will never notice a performance difference between the two.

    Secondly, if in your 12v system, you see a 1-2 volt drop, simply from your wire, well you've obviously sized your wire too small. This is true no matter if your wire is solid core, or stranded. If you are concerned about voltage loss (line loss), I would recommend simply up-sizing to the next larger sized wire, finding some rare extremely low resistance 2awg wire is not necessary.

    In your example, you cite a diffence in Vd of approx 1%. At 12volts, that's an extremely small difference. You will never notice a performance difference in your stereo (or winch) based upon that small of a difference. Its cool you found that stuff, might as well have used it I agree, but again its really not necessary.

    Lastly, I did not mean to imply all 2awg wire is the same, its certainly not. As stated before, strand count affects resistance. *shrug* it does however measure for capacity. My point is we need to remain realistic when dealing with this stuff. A difference of 1% in line loss simply will never be noticed. Your voltage drops an extra .1volt when the bass hits? You'll never hear that difference. Yes, build your charging system as robust as possible. Stiffen it as much as possible. But, there is such a thing as getting carried away. ;) For the average person, normal strand count wire works just fine, as does chassis/frame grounds when applied properly.

    Cheers.
     
  13. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    Yeah, I didn't mean to imply everyone needs the special wire. I was just making the point of the more strands the better, especially over longer distances, which in a truck, doesn't really apply. 15-20', not really a difference, those calculations more pose for hundreds of feet or even miles (like a train :D). Yeah, your right, for a car, not very relavent. Yes, I'm getting carried away, and that's exactly what my EE buddy said.
    Now if I add in the amps the winch could pull (200+), then I see a voltage drop in my 2ga. But I don't think I'll be jambing the tunes, and running a coffee maker on the inverter while I'm winching.

    Normal frame grounds don't last, IMO, here in the rust belt. I've had to redo my '97 K2500 a couple years ago, the taillights and signals were acting goofy. Same for the C10, I had to redo the grounds in that truck in the motor compartment as well (headlights, front sigs etc).
    High amperage stuff is even more sensative on the frame. My EE buddy had to do the QuadraSteer motor for the rear of the the GMt800 trucks, 85 amp load (low duty cycle though), he ran a seperate ground wire back there as well (the finance's dismay). The math wasn't proving viable to ground to frame under that load,too much potential reistance.
     
  14. chevyin

    chevyin 1/2 ton status

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    A large wire connector welded to the frame wont show much resistance. A welded connection wont really suffer much (if any) problem with corrosion. But yeah that is going a bit extreme (although cheaper than running another run of wire for a ground).

    The best way to fight corrosion is to keep out the oxygen. Once Ive done a frame connection, I paint over any bare metal, then undercoat, then paint again. I haven't used these setups in the rust belt, but I have used them in florida and california, driving on the beach alot, and Ive yet to have any real issues with them.

    But dont take this wrong, over all I agree with you running a dedicated wire back to the batt directly is the best method, its just not usually the most bang for your buck choice to make.

    Good discussion here 73k5blazer. :)
     

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