PM for a Truck’s Radio System
This article is reproduced from Gear Jammer Magazine.
The Parts that Get Ignore: Antenna, Stud and Coax
I recently returned from a lot of traveling and visiting with many professional drivers and learned that CB isn’t dead. You just have to get off the phone, take off the bucktooth headset and grab the mic. Y’all got a radio, everyone of you but depending where you travel, you might not be able to even get a radio check. But that doesn’t mean your equipment should be ignored. The folks I met still want a good talking radio but were unaware that the radio setup needs an annual check up and maintenance just like everything else. What I am going to present here is proven, no bullshit applications that will save you money in the long run and have you sounding decent enough that other drivers will at least give you a response, There will be no math or antenna theory discussed, just a practical approach. If you want to discuss theory, you buy the martinis and I’ll argue till the last man standing. Challenge made.
ANTENNA
I am not going to suggest one brand over another. One, I don’t want to start THAT argument, and two, they’re not paying me to be a spokesperson. The most important thing is GET THE DAMN THING TUNED!!! Go to a reputable shop that has an antenna analyzer where they know how to use it. If you buy a SWR meter on the cheap, (yeah I know it’s VSWR, lighten up Francis), the only thing they do is rectify AC to DC and in the world of radio, this can be manipulated as much as the news. Also, don’t be fooled by a 1:1 SWR reading. A dummy load has an SWR of 1:1 and it turns Rf power to heat. The more important issue is where your antenna is resonant and you can only do that with an analyzer. I know right now you’re probably saying “hey this asshole just stated the lowest SWR isn’t the best thing”. “I’ve been setting my stuff to the lowest for years and it works just fine!” By being resonant, your system will be most efficient and have the best radiating ability instead of being a toaster oven. Also, one important caveat, do not believe everything that is advertised! Some like to really exaggerate their performance, and I’m talking antennas here gentleman; ladies, no laughing. There are truly some parameters that are grossly misstated. Beware the bullshit.
Two antennas are NOT better than one. I have seen factory dual antennas installed with 18 feet of RG 58 from each antenna and both pieces of coax rammed into a standard PL 259, FROM THE FACTORY! Wrong coax, wrong length, wrong connector, and to co-phase any antenna system properly, the antennas have to be at least 9 feet on 27 MHz (CB band). Co-Phasing doesn’t work on a big truck. If that is the look you want, make one a dummy. Again, you buy the martinis, and this argument can go on until the fire goes out.
ANTENNA PLACEMENT
A radio wave has two components, an electric field and a magnetic one. So to make everything happy, get the coil above the roof line to the best of your ability. Also if your stainless steel mast is bent to where it looks like a backwards Z, have the antenna tested. If the antenna is tunable, you only need to buy a new mast instead of a complete antenna at one quarter the cost.
STUD
Annual replacement! You can buy the big $30-$40 one that will rip your mirror bracket off before it breaks, but all I have to say is stop hitting shit so hard. I’m kidding, but stop hitting shit so hard! Lean towards the $10 one and the reason is as follows, all dissimilar metals when put together undergo galvanic action. The best representation of this is an aluminum antenna bracket on a chrome mirror rail. When you remove it, there will be enough white powder that, if it’s windy out, you’ll momentarily go blind. More to the point, remove the stud and you will see ridges and dips where the two metals exchanged places. The resistance this creates will make your coax radiate instead of the antenna. Solution, if you buy the expensive one, remove it and clean the crap out of it in the spring time. Chances are you are not taking it apart to do this tedious task, you have better things to do, and, you will probably still have corrosion. Just get the $10 one and replace it annually. It won’t change the tune of the antenna as long as nothing else has changed, but it isn’t a bad idea to get an analyzer on it. Remember the nylon insulator goes on top of the bracket. It’s a common error that occurs a lot. Also, clean up the bracket if any rust or corrosion is on the bottom.
COAX
The only thing I like thin is pasta with my chicken parm. For a rig, 8X is the only way to go, and I have proof. Factory coax, you know the horrible shit they just installed in your $240K rig is RG 58, which is not really RG 58 because it’s not made to the military standards no mo. Hate to say it but “standards” have become almost nonexistent. 8X is almost 60% thicker (and only a quarter inch in diameter) and the number of times I have found RG 58 center conductor broken mid strand with no stress on it is astounding. And yes out of curiosity, I have cut many a coax looking for the failure point and in essence, RG 58 is a failure point. Also, 8X has less loss to it, but that’s another discussion (argument, you buy).
The PL 259 is another common point of failure. Outside, the weather just beats the shit out of it. Inside, it’s probably you. Stand by and just listen. You just dropped a couple of $$$ on a big radio. You positioned the radio at the correct angle so it faces you perfectly. You are freakin ecstatic on how it looks on your overhead. But you never considered the additional inch and a half the coax connector needs. So you screw the PL 259 into the radio, and mash it against the windshield at a 110 degree angle at the very end of the PL 259 and then bitch at me that “I ain’t puttin out!” Two choices here driver. Either re- drill the bracket location, or, put in a 90 degree PL 259. Keep in mind, this is also another failure point because it will loosen up so check it regularly. Even worse is stuffing your big radio into a space that is for a 29 in the overhead. This is one of the leading cause of “my radio ain’t getting out” because of broken coax.
Speaking of loosening up. There is snug and then there is truck driver tight. Never do truck driver tight with your radio system. I’m no slouch but more than once I had to use channel locks to remove the knobs holding a radio in place. The knobs, c’mon man, it’s a knob. Also over cranking them leads to ripping the voltage regulator’s legs right off the board.
You don’t need 18 feet of coax! Get away from it. One reason, and you have to again buy for this discussion, it’s putting a current node at the sweet spot ON THE COAX, not the antenna! It just makes your cheesy meter reading look like everything is perfect. Have it made to the length you need.
One final mention, the Multiplexer that has your AM/FM work on the CB antenna, pull it freakin out and run it over. A good duplexer, diplexer, multiplexer, whatever term you want to use, will cost 3 times the amount of what is in the truck now, but don’t bother.
Stay Safe,
Mark
Email me at: Mark@nbsr.online
"To those who fight for it, life has a flavor the protected never know."