One of the things I notice about the differences in the two is not only the different "culture" of them, but a vast difference in the technical approach to the radios themselves. Without getting into a vast discussion on one of these subjects, I do notice the constant attention of CB ops to so-called coax length and an obsession with what they call SWR's (ssssssssssss) whose plural pronunciation (more often than not) indicates a lack of basic understanding of what SWR (SINGULAR!) is!
On the CB boards that I casually read, there is almost an OBSESSION with this "coax length" issue whereby the operators seem to be "tuning" their antennas by trimming their coax to a certain length while completely IGNORING the REAL way to set an antenna so it will resonate on a particular band or frequency! Many of these "experts" proudly launch into a vast discourse on velocity factor (VF) and complex formulas that seem more intent on impressing the reader than actually achieving RESONANCE.
So what IS this velocity factor thing? Simply put, it is the speed at which an RF signal travels thru a medium. It can be AIR, WATER, WIRE, or a CABLE (same thing as wire, really). But that is ALL it is. PERIOD!!!! IT HAS LITTLE TO DO WITH 'TUNING' OR RESONATING AN ANTENNA! Worrying about it and including it in a bunch of formulas is utter horses---!!!!!
I see this formula that goes something like 492+ or - VF/frequency in mhz-yada yada yada= so 'n so coax length! HA! It, for the most part, and for a CB or any OTHER antenna, IS-UTTER-HOOEY-AND HORSE-DUNG!
The question is: can you "tune", or SHOULD you "tune" your CB antenna by trimming your coax to a certain length? NO! So what SHOULD you do?
For a normal installation that has adequate metal, enough to serve as the other half of your antenna (remember that that whip sticking up on your car IS only HALF of your antenna system) you should first assure that the whip is in the clear of obstructions (let it "see" over the car). Then you should loosen the set screw for the whip (for coil type antennas) and slide it UP or DOWN in the collet while observing the SWR (NOT SWR'sssssssssss). Another hint is to straighten out a hanger and use it as a substitute for the whip if the stainless whip doesn't let the antenna "tune". This way, you don't ruin a good whip by accidentally cutting too much off! Run whatever length of coax you need to the radio and fergeddaboudit! Can you tune antennas cutting coax? Yes and no. What you are doing is fooling your SWR bridge into reading a 50 ohm match and a "good" swr. BUT! The antenna IS STILL MISMATCHED BECAUSE IT HAS NOT BEEN SET TO A "TRUE" AND ACCURATE RESONANCE!!!! What you have is an inefficient antenna. Remember those little 5 watt "dummy load" things that ALWAYS show a "good SWR no matter what? That's because they are nothing more than a RESISTOR with an 50 ohm impedance!!!! In effect, your antenna, because it is being "tricked" by the coax (which IS 50 ohms, BTW) becomes, more or less, a sort of resistor that exhibits varying kinds of radiation because it has not been "set" to a "true" SWR.

If the coax at a certain length was so good at radiating a signal, then WHY would we even NEED the antenna?

Finally, the only time that coax should be a "certain" length is in certain "phased" setups or when the ground (or counterpoise) is not sufficient. (Remember the above comments about the vehicle being the OTHER half of the antenna system?)

One of the glaring differences in amateur operations and CB is the LACK of the obsession with coax length with respect to CB. Look at the amateur discussion boards where you find very little discussion of "coax length" or the same preoccupation with it vs CB boards. While there ARE some situations where coax may be required to be certain lengths (some special folded dipoles, verticals, etc), it is generally very unusual.

Here's ONE amateur who has NEVER resorted to "cutting" coax to a certain length in order to resonate an antenna system unless it was an integral part of the mfr's design! (ME!)

73

CWM

Hey C.W.Morse

I fear the cb operators will never catch on to this and continue their wrong perception of coax length being used to trim out the "swr's" of their antenna

Perhaps one of the reasons i did so well as a CB operator is i learned early on such coax lengths and cutting is indeed nearly always useless

But hey
they have to come to terms with it on their own
you can lead a horse to water...lol

Thank you CWM.

May I copy that and paste it to a few other forums I am a member of?

I told a guy to use as much as it takes to get the job done on another forum and damn near lost my head.

I have a few friends that are Ham Op's and they all told me exactly what you just posted. But in many less words.

"Leave the f***ing coax alone and tune the g** damned antenna." I believe were the exact words.

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MoJo
www.mojoenterprises.us

no doubt you have a wealth of true knowledge to share .
however , your HOLY THAN THOU way of saying things will not inspire some (the very people youre wanting to communicate to) folks to listen to the message . some may start out feeling offended and it over shadows anything you try to say after that .

either develop people skills or higher a publicist .
youll get a better response then .

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Frank Zappa observed, "It's not getting any smarter out there. You have to come to terms with stupidity, and make it work for you."

My pet peeve with CBers (and I am one) is when they refer to a single yagi antenna as "a set of beams".

That drives me crazy! It is a beam, not a set of beams.

__________________
Highlander, NA-821 on 11 Meters.
N9RZF, David on Ham Bands.

Yaesu FT-847, Galaxy DX-2517, President Lincoln, Cobra 150 GTL, Uniden Grant LT.

IT'LL ALL BE BETTER NOW THAT WE HAVE A NEW PRESIDENT AND WHEN WE GET TO THE NEW PLACE ...

(I like the "either develop people skills or higher a publicist" idea)

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Tuning your VSWR by adjusting coax length?

What of the tried & true 18 foot coax rule of CB radio?

Either you keep the coax at 18 feet, or you're tuning it for lowest VSWR, but not both.

I would really like to see what happens when they plug in a 4 pill amplifier to this antenna tuned by coax length. I think either RF burns would occur or smoked amplifier.

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"Y'all mind hanging back? You're jamming my frequencies" -- Tangina in Poltergeist

Wrong again. A beam holds up a roof. What you have is either a yagi or a quad or something of that sort.The antenna "beams" the signal in a given direction.

I'll be quiet now.

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Light travels faster than the speed of sound, this is why some people tend to appear bright, until they decide to speak.

When I started in CB, there were two CB shops local to me, one was a "good one" and one was a "bad one". The first place I ever heard the 18 foot of coax myth was the "good" CB shop. This man was in business for probably 35 years and even owned a patent on an antenna product and later sold it to a large CB antenna manufacturer. I believe he also had a Technician plus license.

It's the guys that should know better that propagate the biggest CB myths out there, fortunately with the internet it is very simple for anyone with the motivation to learn more than their local CB Saint ever knew in his life. It is a lot easier to make a few bucks off a guy by handing him a piece of coax and charging him for the new coax and the "antenna tune" than figuring out what is wrong with the antenna system itself.

It's hard not to classify it as anything other than taking advantage of another person's ignorance, just to make some easy money.

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"IT'S A SEARS ROADTALKER WORLD"

a long time ago, some very smart guys got together and said,
"we need a means of getting a signal from a transmitter to an antenna, without having to worry about the length of the feedline."

VOILA!
they invented coaxial cable.
brilliant!!!

has anyone asked themselves why the product exists in the first place?

THE WHOLE POINT OF USING COAXIAL CABLE TO FEED YOUR ANTENNA IS THAT THE LENGTH DOESNT MATTER!!!!

if changing the coax length changes your SWR; that is a tell-tale sign that your antenna is out of tune.

why this would ever be an issue in a service that only covers .45mhz i will never know. LOL

good luck to you guys out there who will still take the time to try and explain the "why's" to the uneducated.

In my opinion, if Lou Franklin's book "The Screwdriver Expert"s Guide", didnt dispel the myth; nothing ever will.

later,
LC

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well yeah, but what's really going on?