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Posted: 9/6/2010 6:56:32 AM EDT
[Last Edit: 9/6/2010 6:59:59 AM EDT by WildApple]
You guys have any pointers on hooking up a CB?

I just got a couple cheap'o units from Walmart for $35 a piece

What now?

Do I have to "match" the CB antenna....Do I need a tool for that?
Link Posted: 9/6/2010 7:11:38 AM EDT
Most prepackaged antennas are pre tuned, so plug and play. But if you're curious you could go to Radio Shack and buy an SWR meter.

Link Posted: 9/6/2010 7:14:18 AM EDT
I'm guessing it is pretty much plug and play. Good grounds for the power negative leads. If you can, borrow an SWR bridge to be sure the antenna system is working. If you have to adjust anything it most likely will be a sliding tip on the antenna. You will need an extra coax jumper to attach the bridge to the radio. That should do it.

Pav
Link Posted: 9/6/2010 7:21:29 AM EDT
Originally Posted By WildApple:
You guys have any pointers on hooking up a CB?

I just got a couple cheap'o units from Walmart for $35 a piece

What now?

Do I have to "match" the CB antenna....Do I need a tool for that?


Post a pic or link to the units and antennas

Most antennas do need to be tuned (since each installation is different)
Tuning provides for Max transfer of power from the transceiver to antenna.
So if it is out of tune you do not get full efficiency
Link Posted: 9/6/2010 7:21:42 AM EDT
We have a ham radio forum in the outdoor section, you might find more help there.
Link Posted: 9/6/2010 7:37:44 AM EDT
If you are tuning your antenna, be sure to cut only a 1/4 to 1/2" off the antenna at a time. You can take some more off if needed but can never add to the length. I try to tune especially for ch19. Its in the middle of the band. Channels 1-5 and 35-40 may still clip a little but I rarely use them anyway.
Link Posted: 9/6/2010 7:50:56 AM EDT

Originally Posted By pilotman:
Most prepackaged antennas are pre tuned, so plug and play. But if you're curious you could go to Radio Shack and buy an SWR meter.


This.

And don't expect too much from that cheapie.
Link Posted: 9/6/2010 8:15:06 AM EDT
Run Black to metal ground near battery. Run Red to positive side of battery. Run coax from CB to antenna mount. Mount antenna mount to good metal area. Mount 102" SS Whip (no Spring) in antenna mount. Turn on and you are ready to start talking.

When you get tired of all the foul language you can get a ham license.
Link Posted: 9/6/2010 9:41:28 AM EDT
I don't know...75-meters gets pretty bad some times......not like it used to be.

Pav
Link Posted: 9/6/2010 9:45:35 AM EDT
Originally Posted By pavil58ar:
I don't know...75-meters gets pretty bad some times......not like it used to be.

Below 3600, this isn't an issue.
Link Posted: 9/6/2010 10:12:03 AM EDT

Originally Posted By pavil58ar:
I don't know...75-meters gets pretty bad some times......not like it used to be.

Pav

What does 75 meters have to do with CBs?
Link Posted: 9/6/2010 10:26:23 AM EDT
Originally Posted By pilotman:
Most prepackaged antennas are pre tuned, so plug and play. But if you're curious you could go to Radio Shack and buy an SWR meter.




Or you could go to a truck-stop that supports CB radios.

Also, most large truck maint. companies have services for this very thing
Link Posted: 9/6/2010 10:31:48 AM EDT
Originally Posted By RedHotChiliPepper:
What does 75 meters have to do with CBs?

A) It's RF;

B) The language and operating practices have become quite similar over the years.


Link Posted: 9/6/2010 10:35:56 AM EDT
[Last Edit: 9/6/2010 10:37:20 AM EDT by inthe605]
Red to positive, black to ground, the more steel the ground is connected to the better. But really its going to be immposible to know if its G2G without someone you know having one. Around here even the truckers don't use em much.

Posted Via AR15.Com Mobile
Link Posted: 9/6/2010 10:52:42 AM EDT
You can check out places like cbtricks.com for model-specific mods(legal limit is 4watts out if I remember correctly), and there's one other place I always used to order my radios and parts from...they send out a little gray catalog, I forget the name of the place but if I remember it I'll come back and edit the post. There's all sorts of online retailers, and places to learn a lot of handy info.

I was always a fan of the Galaxy radios, and the higher-end Cobra radios. Dabbled a little in the Unidens once they started getting a little nicer and came with more built-in options. No experience with Connex, but I've heard good things. The Magnums look pretty cool, but I honestly don't know if they're a good performer or just made to look flashy. My last mobile unit was a Galaxy 66v + OEM mic + dual Firestiks. My last base-unit was a Galaxy DX-949 + OEM mic + the add-on freq counter + Antron three section antenna(still up on the house and connected to my Uniden BC350a scanner these days) + some other "stuff".

If you're new to CB radios, and live in a medium-to-high traffic area...be prepared for foul language, especially if you lurk on channel 19 near a busy/popular haul route like an interstate highway. I live near I-44 and almost never tune to channel 19 due to all the garbage on there. It's a lot of fun if there's other CB enthusiasts in your area, out here we had channel 5 to talk on with zero interruptions. I got bored with it after a while, so I don't have any equipment left except for that base antenna. Considered getting in to HAM, just haven't found the time to look in to the testing or even study anything.
Link Posted: 9/6/2010 11:01:02 AM EDT

Originally Posted By AnalogKid:
Originally Posted By RedHotChiliPepper:
What does 75 meters have to do with CBs?

A) It's RF;

B) The language and operating practices have become quite similar over the years.



Ah, I'm with you now. Seems the good 'ol boys clubs like to hang out on 80 and 75 and anything goes. I was under the impression that such language was forbidden on the air, but I guess no one cares anymore like they should.
Link Posted: 9/6/2010 11:03:34 AM EDT

Originally Posted By johnny_dot_exe:

Considered getting in to HAM, just haven't found the time to look in to the testing or even study anything.

Technician test... go!
Link Posted: 9/6/2010 11:06:36 AM EDT
[Last Edit: 9/6/2010 11:09:04 AM EDT by GySgt_D]
The airwaves are like one big 4-Chan. Unmoderated.

They go to hell as soon as the riff-raff show up, which is why a lot of us hated it when they removed the code requirement from the FCC exam. There are enough a-holes that could pass it. Now we have them and undisciplined a-holes with nothing invested.

Excellent advice on mobile antenna mounting and technical issues (ham band focused, but RF is RF...)
http://www.k0bg.com/
Link Posted: 9/6/2010 11:23:19 AM EDT
Antenna performance will depend a lot on having a good ground. The BEST way to mount the antenna is to drill a hole in the car body (best radiation pattern on a car, will be mounted directly in the middle of the roof). You, like most people, will probably never do this and will instead opt for a magnetic mount, which will scrape the hell out of your paint and chafe underneath the coax. Don't say I didn't warn you ahead of time.

It works well enough, though.

"Matching" the antenna as it were, is a matter of checking it's resonance on the desired frequency. A properly functioning and matched antenna will radiate nearly all of the transmitted power. If the antenna is not resonant on a given frequency, some of the transmitted power will be reflected back towards the transmitter. Too much power reflected back has a tendency to harm the final transistor(s) in the transmitter, though modern CB radios have protection mechanisms that throttle back the transmitter power when this is detected. Even so, any power being reflected back towards the transmitter is power that is not being radiated by the antenna. In reverse, it also means your receiver's functionality is less than ideal.

An antenna that is at an improper length for the desired frequency is only one thing that can affect it's resonance. A poor ground will do it, defective coaxial cable will do it, poor connections will do it, etc. A perfectly resonant antenna will present a feedpoint impedance of 50 ohms to the transmitter, which along with the coax, also has an impedance of 50 ohms. Anything that causes the impedance of the system to deviate from 50 ohms, will result in some of that transmitted power being reflected. These reflections are called standing waves, and the difference between the maximum and minimum amplitude of the standing waves, are expressed as a standing wave ratio (SWR).

With CB radios, the equipment used to measure amplitude of the standing wave is going to be measuring in volts, so it's properly called the Voltage Standing Wave Ratio, or VSWR. A VSWR of 2:1 means that the maximum voltage of the standing wave is 2x greater than the minimum voltage of the standing wave. A VSWR of 1:1 means that the maximum and minimum amplitudes of the wave are identical, i.e. there is no standing wave (this is more theoretical - there's always going to be something).

To measure the VSWR, you'll need a meter. They're around $30, give or take. You can follow the instructions that come with it, but it's pretty much works like this: After inserting the meter between your transmitter and antenna, you select a frequency in the middle of the range of frequencies you wish to use (say, channel 20 on a CB radio). You then calibrate the meter by transmitting on that frequency with the VSWR meter selector switch set to FWD, and adjusting the meter until the needle indicates maximum VSWR (it's usually denoted with something like "set" at the end of the scale). While still transmitting, you flip the switch over to REF and note the reading on the meter. This is your VSWR.

On a CB, anything at 2:1 or lower is perfectly fine. Some (better) antennas allow you to adjust their length (the length of the antenna changes it's resonance on a given frequency, and thus the feedpoint impedance at that frequency). If you can manage a VSWR of 1.5:1, you're in great shape and can call it a day. People that feverishly labor to lower get it any lower than that on a CB are wasting their time for almost no realized benefit (another topic I'd be happy to discuss, math included, should there be any disagreement).

With a decent, well made commercial antenna (Wilson, K40, etc) a VSWR over 2:1 nearly always indicates a poor installation. Bad coax, poor ground, bad connection, etc.
Link Posted: 9/6/2010 12:38:12 PM EDT
Sorry for the sort of obtuse post. Foul language was mentioned and I just thought of how bad it gets on 75 meters sometimes. I guess 40 and 20 are that way too. Language like that would never have been used years ago. There was a little more self control and some respect for everybody as opposed to the 'I can say whatever I darn well please' attitude. Society changes......

Pav
Link Posted: 9/6/2010 3:33:45 PM EDT

Originally Posted By glazer1972:
Run Black to metal ground near battery. Run Red to positive side of battery. Run coax from CB to antenna mount. Mount antenna mount to good metal area. Mount 102" SS Whip (no Spring) in antenna mount. Turn on and you are ready to start talking.

When you get tired of all the foul language you can get a ham license.

Whaddya mean? Those foul mouthed a-holes can be entertaining, although listening to Lavender Larry constantly talk about not having any panties on gets old.


Originally Posted By tweeter:
Originally Posted By pilotman:
Most prepackaged antennas are pre tuned, so plug and play. But if you're curious you could go to Radio Shack and buy an SWR meter.




Or you could go to a truck-stop that supports CB radios.

Also, most large truck maint. companies have services for this very thing

Look for a CB shop.
Link Posted: 9/7/2010 12:11:02 PM EDT
Thanks for those instructions subnet!

We are getting portable cb's, with the magnetic antenna. We kind of need one that we can take with us after we leave the truck. We have some older unidens now, and they work ok for listening. We saw some midlands on amazon that can be hooked up to an external antenna that got pretty good reviews.

My trucks already scratched up.
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