Increasing CB Radio Range (Is Illegal)
03-11-2010, 02:20 AM
#1
JK Jedi Master
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Increasing CB Radio Range (Is Illegal)
Well, I see that the latest thread on improving CB radio range has been closed. In researching this post, I came across a website that details the fines the locally-based Love's Corporation had to pay for illegally boosting the output of CB radios. The chances of you getting caught? Probably close to zero, but the FCC is targeting places that do the mod's.
I just want to offer up one more reason why it's really not worth it. RF range is a logarithmic function. If you take a 4-watt CB radio and boost it's output to 32-watts, that is not an eight fold gain (32/4). It is a 9-DB gain. If you then put that into the formula for path loss calculation, you will learn that the theoretical range for a legal CB radio is 2.2 miles. The theoretical range for a 32-watt CB radio is 3.7 miles--a mile and half improvement. That's theoretical. Truth is, that assumes perfect line-of-sight with no intervening path loss components (hills, vehicles, buildings, trees, etc). Real life suggests that boosting your radio from 4 to 32 watts will give about a 1/2 mile improvement--on the highway. On the trail, line-of-sight is usually going to determine whether you're heard, not RF power output.
It's illegal. It increases spurious emissions that cause interference with other devices (most notably broadcast TV, but sometimes even cable TV and telephone service). And it provides NO (ZERO, NADA, ZIP!) improvement to hearing the other guy, unless he also chooses to break the law and modify his radio. At the end of the day, modifying a CB radio to "tweak" it's output is a waste of time and money.
If you want to run the numbers yourself, get out your scientific calculators and visit here ...
http://web.arundale.co.uk/docs/ais/AppNote_UHF_VHF_Calc.pdf
I just want to offer up one more reason why it's really not worth it. RF range is a logarithmic function. If you take a 4-watt CB radio and boost it's output to 32-watts, that is not an eight fold gain (32/4). It is a 9-DB gain. If you then put that into the formula for path loss calculation, you will learn that the theoretical range for a legal CB radio is 2.2 miles. The theoretical range for a 32-watt CB radio is 3.7 miles--a mile and half improvement. That's theoretical. Truth is, that assumes perfect line-of-sight with no intervening path loss components (hills, vehicles, buildings, trees, etc). Real life suggests that boosting your radio from 4 to 32 watts will give about a 1/2 mile improvement--on the highway. On the trail, line-of-sight is usually going to determine whether you're heard, not RF power output.
It's illegal. It increases spurious emissions that cause interference with other devices (most notably broadcast TV, but sometimes even cable TV and telephone service). And it provides NO (ZERO, NADA, ZIP!) improvement to hearing the other guy, unless he also chooses to break the law and modify his radio. At the end of the day, modifying a CB radio to "tweak" it's output is a waste of time and money.
If you want to run the numbers yourself, get out your scientific calculators and visit here ...
http://web.arundale.co.uk/docs/ais/AppNote_UHF_VHF_Calc.pdf
03-11-2010, 07:06 AM
#2
JK Jedi
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One thing that you CAN do legally is get an aftermarket mic. Astatic makes a transistorized handheld that is fantastic. I think the one I had was a M-575. It uses a battery and has a volume and tone control. Tone control is important as you can tailor the tone of your voice. Highs freq. response tend to get out better than low end bassy ones. Audio, by itself, has a whole lot to do with the "talk" power of your radio.
Also....Upper and lower SSB is a far more productive means of communication than noisy AM. Plus most CBs that have SSB tend to modulate up to about 12 watts on peaks.....and that's from a legal off the shelf radio.
Also....Upper and lower SSB is a far more productive means of communication than noisy AM. Plus most CBs that have SSB tend to modulate up to about 12 watts on peaks.....and that's from a legal off the shelf radio.
03-11-2010, 09:32 AM
#3
JK Jedi Master
Thread Starter
Excellent points, Dave. And, with SSB you can have a narrower passband, which further reduces that noise level. The only downside (well, other than cost): Will your trail buddy have SSB?
03-11-2010, 01:47 PM
#6
JK Jedi Master
Thread Starter
A small aside: I was fixing the RF cable in my Jeep the other day (just installed a new rear bumper) and while I was trying to do a radio check the CB band must have been open. LOL: This too is illegal, but it's hard to resist the temptation to talk to someone four states away. Anyway, I wasn't hearing the distant stations, but obviously others were, because half a dozen channels had people working them. Actually, they were probably being legal. I would hear them ask, "Where are you?" .... "Tampa? Okay, got to find someone closer to talk to; have a nice day!"
03-11-2010, 02:57 PM
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In addition to a better mic, To get the maximum legal range and best reception on any radio or frequency, focus on the details of the antenna installation. A properly installed and tuned antenna is better than twice the power.
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03-11-2010, 04:14 PM
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I Live about 8 miles from the interstate just had a local shop tune my cb before i couldnt talk to anyone on the interstate at all now i dont have a problem talking that far
03-11-2010, 07:29 PM
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