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southern runner
| | Posted on Friday, October 03, 2003 - 8:39 pm: | 
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this I know,2x2290 driving 4 2879,2 fans,rf meter,hi,med low switch,preamp,it is susposed to do 1200,with 1 watt radio?can anyone provide help on this,and what about the 12-40 antenna?,I found on one of the other pages,here,that a 900 palomar,had same pills,how can that be?also how do you protect,your computer,on your truck,while using your amp?
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fancypants
| | Posted on Saturday, October 04, 2003 - 1:26 am: |
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This type of amp is commonly called a "2X4" and is NOT a good idea for daily use. Not only are you over-driving the tar out of the 2879's IF the 2290's are tuned for max output, but the output from the amp will be much dirtier ( both in-band and out of band ) due to this overdrive condition. Besides all of that, i would expect to see current draw of about 80 - 125 amps from the electrical system, meaning that this would require a dedicated alternator / battery on most big trucks. I don't think that you want to go down the road and have your truck die or your chicken lights dim every time that you key up : )
As far as "killing the computer" on any vehicle, the biggest factors involved are minimizing stray RF, proper antenna selection / installation / tuning and running BOTH power leads directly back to the battery.
By using coax that is of a high grade with heavy shielding ( "REAL" RG-213, double shielded mini 8, etc.. ), having the cable properly assembled ( soldered shield to an Amphenol PL-259 ), mounting the antenna as high up as possible and getting the bottom of the coil well above the flat of the roof-line, you should be okay. Obviously, making sure that the antenna is properly grounded, tuned and is able to easily accept the power from the amp ( load up ) without the swr going up drastically goes without saying. No coils, loops or wadded up coax cable either. It should be strung out as straight as possible with any bends being made very gradually. DO NOT spiral wrap coax around the mirror arm either as this creates BIG problems.
As far as the DC power connections are concerned, taking the positive and negative cables and arranging them into a twisted pair helps to reduce the potential for RF to travel back down the leads and use them as an antenna. Placing a large ferrite choke on BOTH the positive and negative leads at the amp also helps this out too.
When doing something like this, always make sure to fuse the system right AT the positive side of the battery. Look at what the amp has in it for fuse(s) and then go "slightly" above that figure for the fuse at the battery. Obviously, weatherproofing all of these connections and making sure that the power cords aren't going to rub or chafe against the chassis is a good idea.
If you follow these directions, you can run BIG power in a truck without much of a problem. Just keep in mind that ALL antenna systems need basic maintenance performed on a regular basis. At least twice a year, the entire antenna system ( antenna, mount, stud, coax, ground cable, etc... ) should be taken apart, cleaned with a wire brush, given a full inspection and re-installed. If you do this in the spring and in the fall, you'll be miles ahead of the other guys in terms of strong and reliable radio performance. |
Tech833
| | Posted on Saturday, October 04, 2003 - 12:12 pm: |
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If your antennas are installed properly with quality hardware and all connections sealed (with Penetrox and W/P sealant) the first time, tearing the system apart for periodic cleaning would not be required. |
Bigbob
| | Posted on Saturday, October 04, 2003 - 11:52 pm: |
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The very best way to keep RF out of your system is to make sure your ground plane is at absolute ground potential and that your computer box is under it,the worst thing you can do is run a trunk lip mount antenna with an amp,because the back window will not keep RF out,you irradiate everything inside including yourself,bottom line keep your computer box out of the radiation pattern. |
southern runner
| | Posted on Sunday, October 05, 2003 - 9:57 am: |
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what does that mean? to have your computer under it? |
Bigbob
| | Posted on Sunday, October 05, 2003 - 2:19 pm: |
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Talking mobile use,keep it under the ground plane or fully shilded. |
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