When i speak into the mic i can hear myself talk through out the truck in the audio speakers. I drive a 387 pete i got good connection its just i can hear myself when i talk through the speakers
Does your "pete" have a fiberglass body? I suspect it does. If this is the case and you are using mirror mount antennas, are they the new "no ground needed" or "ground free" antennas?
If this is the case, check or have checked your SWR. (I get a lightening bolt down my neck when I hear it called "SWR'S".)
S.W.R. stands for Standing Wave Ratio. In the words of The Highlander, "There can only be one". What this is is the amount of your signal that is being absorbed / radiated by your antenna system, (including your coax), as opposed to how much is being sent back down the coax and back into your radio. If your SWR is too high, not much is going out the antenna and is being reabsorbed by your RF FINAL, (another bolt!!!). Most radios except for some modified hams or high power exports HAVE ONLY ONE FINAL TRANSISTOR!!!. If you have a standard Cobra 29 out of the box, you have ONE final TRANSISTOR. I don't mean to yell at you. These are just my pet peaves.:) Anyway, imagine that you have a rope tied to a building. You pull it fairly taught and whip it up & down once. That wave will move away from you, hit the building and come back and shake your hand. This is high SWR as all of your power came back to you. If Superman were to shake that same rope and that wave took that building off it's foundation, this low SWR as all of his power was radiated by the building. This is how you want your antenna system to work. If your SWR is too high, your radio is trying to put out 4 watts. That same 4 watts is coming back down the line out of phase and now your final is being asked to handle 8 watts when it will only made to do 4, (all in a perfect world of course:). If you were fooled into buying these "no ground" antennas as so many truckers are, I am sorry. These should only be used as a last resort when nothing else works. These antennas have what's called a matching stub in their coax plugs in the case of the single mast marine type antenna or the antennas, (in the duals), have a matching capacitor in them. Both of these "tricks" fool the radio and SWR meter into thinking that the match on the system is acceptable when it really isn't. For electronic reasons that are really too long to explain here, (you really don't want to get me started:), the low SWR reading is only an illusion. Instead of your signal being radiated completely by your antenna, a major portion of it is being absorbed by either the matching stub or matching capicitors. All of this energy has to go somewhere so some is converted into heat energy in the matching circuits and some is re-radiated to the nearest ground. Unfortunately that will be the wiring of your truck especially if the body is fiberglass which does nothing to stop radio waves.
If you get a weekend off and your boss, (if you're not an owner / operator), doesn't mind you taking your truck home for the weekend. If you know someone with a pair of antennas and a co -phase harness that they can loan you. Set up your mirror mounts in normal fashion with STANDARD antennas. Run your co-phase harness where it won't get pinched up to your radio.
Here's the trick, gain access to the inside of BOTH doors, get ahold of some coax SHIELD braid. Preferably something heavy like off from RG-8 or atleast RG-8X. Get to the nut that holds the mirror to the door that is closest to the door hinge on BOTH DOORS. Clean it up with sand paper so it's nice and shiney AT BOTH ENDS and wrap 1 loop of braid around that bolt inside the door, put a flat washer over the braid and put the nut back on tight without breaking it of course. Take the other end of the braid to 1 bolt of the door hinge, clean it up shiney under the bolt head and matching surface of the hinge, wrap a loop of braid around then bolt and tighten it up. Be sure to leave enough slack in the braid so you don't rip it out when you open the door. Wire will work but braid is better. If you can get ahold of the wide ground strap like they used to use to ground car bodys to their engines, the bigger the better. Radio waves travel on the OUTSIDE of any conductor. Braid has more surface area than a piece of wire. BEFORE you transmit, get the SWR checked and adjusted if possible and/or necessary. I say to borrow the equipment rather than buy it at first because this works in about 85% of installations and I'd hate to see you invest in a new antenna system to find out you're one of the 15%. If this is your problem and this fix works, you'll be amased at how much farther you'll get out with all of your power making it's way out rather looking like the northern lights around you.
I'm going to bed now, (7:33am here). Hey, 73's to ya'.
Jan 15, 2011 |
Cobra 19 DX IV CB Radio