CB Myths

[prerunner1982]

As with any hobby myths taken as fact are present.

There are two common myths that would apply to someone wanting to install a CB into their Jeep.

1st: And probably the most common is that you HAVE to have 18' of coax. You only NEED enough coax to get from your radio to your antenna. If that is 18' then great... but if 10' or 3' will do there is no need for the rest. The reason 18' is usually suggested is because it most easily tricks your SWR meter (used for tuning the antenna) to show that you have a good match and efficient antenna when in actuality your antenna is not any more efficient you are just tricking the meter to tell you so. Trimming the coax to change the SWR is doing the same thing. You tune your antenna for best SWR not the coax. Coax just allows your signal to get from your radio to your antenna... nothing more. To me this myth is like saying you need a certain length of hose depending on PSI or a certain length of wire depending on amps.

2nd: Don't coil your coax. Coiling coax is commonly used by radio operators using much more power and much better antennas than you will use/find on your or your buddies Jeep. It's called a Choke and it helps prevent stray signals from travelling down the coax. I wouldn't purposely build one into your CB radio but if you have some extra coax it shouldn't hurt.

I run some odd length of coax, something around 14' and have coiled the extra... with a 1.1-1.2 SWR and 2.5 watts and 102" I have no problems "getting out".

[nickyg]

It's also a myth that rocking the steering wheel back and forth while talking ingresses signal strength

[tinythexj]

RIP James Best. I have my antenna mounted between the fender and hood and the 9' of cable is just right as far as length and do great when transmitting and receiving.

The two other myths or issues would be antenna mount and antenna related.

[prerunner1982]

The two other myths or issues would be antenna mount and antenna related.

What myths are you referring to?

[GoneWithTheWind]

I was told by a guy that has a cb business that you need the 18' of coax, and it needs to be bundled in a long oval and tied down along the inner fender. The antenna has to mount on the driver side of hood because the signal rotates in a clockwise direction and needs to bounce off the hood. He put the meter on it and told me I was good to go. I had a better cb in the past w/duel antenna, installed it myself w/coiled coax and it worked great. Now I have a Cobra 19dx, single fender mount antenna and I'm not happy w/it. Should I cut and coil my coax? Or get a better cb? I don't have a meter to check it with, and I don't want to go back if the guy is just full of it.

[prerunner1982]

He was full of shit.

The best place for the antenna is on the roof.. I have mine on the drivers rear taillight. Fender mount works too, but anything other than in the middle of the roof is a compromise. (mag mount on roof isn't really better due to the mag mount).

The signal radiates from a vertical antenna in all directions, can't say I have ever hear the whole clockwise rotation explanation though.

If you have 18' of coax it's fine, but it's not required. If you feel comfortable cutting and soldering on a new end go for it. It will give you less excess to hide/deal with. PL-259s can be tricky to solder though, too hot and you melt the insulation inside.

As far as your Cobra 19DX (same radio I use by the way) I would hook a SWR meter up to it first. The mount may need to be cleaned or grounded or the coax could be damaged/bad which would cause the SWR to be quite high and the performance of the radio to be quite low.

[Mudderoy]

I was told by a guy that has a cb business that you need the 18' of coax, and it needs to be bundled in a long oval and tied down along the inner fender. The antenna has to mount on the driver side of hood because the signal rotates in a clockwise direction and needs to bounce off the hood. He put the meter on it and told me I was good to go. I had a better cb in the past w/duel antenna, installed it myself w/coiled coax and it worked great. Now I have a Cobra 19dx, single fender mount antenna and I'm not happy w/it. Should I cut and coil my coax? Or get a better cb? I don't have a meter to check it with, and I don't want to go back if the guy is just full of it.

:wow: :sign0181:

[Mudderoy]

He was full of shit.

The best place for the antenna is on the roof.. I have mine on the drivers rear taillight. Fender mount works too, but anything other than in the middle of the roof is a compromise. (mag mount on roof isn't really better due to the mag mount).

The signal radiates from a vertical antenna in all directions, can't say I have ever hear the whole clockwise rotation explanation though.

If you have 18' of coax it's fine, but it's not required. If you feel comfortable cutting and soldering on a new end go for it. It will give you less excess to hide/deal with. PL-259s can be tricky to solder though, too hot and you melt the insulation inside.

As far as your Cobra 19DX (same radio I use by the way) I would hook a SWR meter up to it first. The mount may need to be cleaned or grounded or the coax could be damaged/bad which would cause the SWR to be quite high and the performance of the radio to be quite low.

Remember every inch of coax is loss of signal strength and loss of power to the antenna.

Antenna placement depends on what you're trying to accomplish.

Center metal up high is a general all purpose to mount for a mostly spherical radiation and reception pattern. If you're doing a lot of highway driving and you want to "aim" your signal down the highway, rear passenger is best. The effect is only slight but the effect is real.

Dual antennas are generally used on 18 wheelers since they have large reflective surfaces behind them, a.k.a. trailers. The antennas on both sides help them transmit equally on both sides of the truck/trailer. They will have a "dark" spot on transmit and reception from the trailer.

I knew this one guy that had phased whips and a little box that allowed him to adjust the phasing. He was able to use it to tune the direction of his receive and transmit. Basically an electronically controlled directional beam antenna system.

[GoneWithTheWind]

Thank you Jon, that's a big help! Dose the meter box do the adjusting? would a radio shack meter work? Tony I haven't had a cb for a while, but that's about how I felt talking to him. I'll try to post the info he gave me, it's pdf and has his info is on it.
oops.
File:///C:/User/Tim/Documents/CB%20installation.Pdf
Thanks again.

[GoneWithTheWind]

Thanks Mudderoy, If that's the case then I can get rid of 10-12 feet of coax. I just need to know how to tune it first be fore I start cutting. I'm going camping in the next day or so and would like to do this before I go. My to do list keeps getting longer.

[Mudderoy]

Thank you Jon, that's a big help! Dose the meter box do the adjusting? would a radio shack meter work? Tony I haven't had a cb for a while, but that's about how I felt talking to him. I'll try to post the info he gave me, it's pdf and has his info is on it.
oops.
File:///C:/User/Tim/Documents/CB%20installation.Pdf
Thanks again.

I see you log on to your Windows 7, or later PC as Tim. :D

That link won't work for anyone on the Internet. The file has to be copied to a server that SHARES the file to the Internet.

[GoneWithTheWind]

I still have a lot to learn. I'll take a pic of it and see if I can get that to work.

[prerunner1982]

Thank you Jon, that's a big help! Dose the meter box do the adjusting? would a radio shack meter work? The meter just does the metering, you do the tuning at the antenna. Radio Shack meter will work fine.


Thanks Mudderoy, If that's the case then I can get rid of 10-12 feet of coax. I just need to know how to tune it first be fore I start cutting. I'm going camping in the next day or so and would like to do this before I go. My to do list keeps getting longer.

What kind of antenna do you have? Some have a tuning "knob" under a cap at the top of the antenna, some you adjust by loosening a set screw and moving the metal part of the antenna up or down and then tightening the set screw, some you actually have to cut the antenna.

[GoneWithTheWind]

Here's a pic of the info I was given.
http://DSC00485.JPG

[GoneWithTheWind]

The antenna is a Tiger Everhardt. would the ideal swr be 1.1-1.2 ?

[prerunner1982]

Looks like it has a piece of metal at the end that you may adjust in/out by loosening a set screw.

[GoneWithTheWind]

Just getting back home w/swr meter, radio shack doesn't make them anymore. I found the screw. Thank you all for all the help!
(just found the thank you box)

[tinythexj]

What myths are you referring to?

Just because its designed for your application doesn't make it plug and play. Sometimes surface or bracket prep is required. Although the metal whip antennas are good you can achieve good SWR numbers with a fiberglass antenna like a Firestik.

[GoneWithTheWind]

I had a reading on ch 40 of aprox.3.5, I pulled wire off the antenna until it read 1.5. Ch 1 barely registers at 1. Since I trimmed the antenna before I trimmed the coax, will I need to get a new antenna if I trim the coax now?

[prerunner1982]

I had a reading on ch 40 of aprox.3.5, I pulled wire off the antenna until it read 1.5. Ch 1 barely registers at 1. Since I trimmed the antenna before I trimmed the coax, will I need to get a new antenna if I trim the coax now?

IF you are going to trim the coax I would check the SWR again afterwards. 1:1 on Channel 1 and 1.5:1 on channel 40 is about as good as you can expect across the band. 1:1 is perfect.

You can also get crimp on ends for the coax if you prefer to not solder.

[prerunner1982]

Remember every inch of coax is loss of signal strength and loss of power to the antenna.


True but when comparing 18' with something less the loss is negligible. But with long runs yes, and at that point we would likely also be talking different coax.

[Mudderoy]

True but when comparing 18' with something less the loss is negligible. But with long runs yes, and at that point we would likely also be talking different coax.

That is dependent on the frequency and the type of transmission line being used, but at CB frequencies that is mostly correct.

[nickyg]

OK. I have to chime in here. Since receiving signals is something I'm sorta an expert on. The best antenna is the cat mount Reynolds 550. It just gets a little tricky plugging the bugger in from time to time.

[tinythexj]

OK. I have to chime in here. Since receiving signals is something I'm sorta an expert on. The best antenna is the cat mount Reynolds 550. It just gets a little tricky plugging the bugger in from time to time.

Careful handing out your secrets Nicky, the government can quickly find ways to shut down your waffle iron remotely.

[Mudderoy]

Careful handing out your secrets Nicky, the government can quickly find ways to shut down your waffle iron remotely.

NickyG knows this and he's working on a aluminum foil lined Vanta Black suit!

[bluedragon436]

You guys are killing me with this talk about what works better for setups and such... now I gotta order the tail light mount from JCR for the passenger side (wish that had been available when I ordered my drivers side mount)... so that when I do drive it down the highway or whatever I can get the most use out of my CB if I so choose...

[Mudderoy]

You guys are killing me with this talk about what works better for setups and such... now I gotta order the tail light mount from JCR for the passenger side (wish that had been available when I ordered my drivers side mount)... so that when I do drive it down the highway or whatever I can get the most use out of my CB if I so choose...

I don't think the effect is that big. There is so much noise on the "Chicken Band" it generally won't make a difference (I feel). Now if you're in the middle of no where and trying to talk to someone 20 miles down the road, yet.

[GoneWithTheWind]

I looked up the CAT antenna and spent e few hours unwrapping the coax. I twisted it except for the last 18" and wrapped it around my roof rack. It was hard getting the wire into the back of my radio and I used an alligator clip for the ground. I keyed up and got someone from Idaho.

[Mudderoy]

I got a myth for ya.

You get just as much voltage and current from a cigarette lighter as you do running the power lines directly to the battery.

I think this is more important for the 20 to 100 watt HAM rigs but I look at it like this. If I only have 4 watts out on 11 meters, I want as much of that 4 watts as possible!

Take the time to run both positive and negative wires to the battery. Make sure you take into account what your CB radio current rating is (during transmit) and they select the right gauge wire that will handle that current for the length of the wire. I can't remember the rule of thumb, but I think that wire should rated for the max current of your CB plus 25%

[Mayooo]

As a radio junky.. This topic cracks me up

WMAYO WITH MY DUCKPLUCKIN RADIO BREAK BREAK

[GoneWithTheWind]

First of all I want to thank you all again for the help setting up my cb. Today I got a little tired of listening to old TV reruns on my cat antenna, so I took it off my rack, got a Firestick and Cobra 25. Now my swr on ch 1 is 1.2 , and ch 40 is 1.3. Now I'm happy!

[GoneWithTheWind]

Okay, not so happy. when I put the cover back on the end of the firestick the numbers change. No matter how carefull I am not to twist the cover, ch 40 goes up on the meter. Any ideas as to why this is happening? I've been at this for a few days now and put the other antenna back on. It reads 1.3 - 1.7 and seems to work okay.

[Mudderoy]

Okay, not so happy. when I put the cover back on the end of the firestick the numbers change. No matter how carefull I am not to twist the cover, ch 40 goes up on the meter. Any ideas as to why this is happening? I've been at this for a few days now and put the other antenna back on. It reads 1.3 - 1.7 and seems to work okay.

That's strange isn't the cover plastic?

[GoneWithTheWind]

Yes it is, it reminds me of what you'd dip tool handles in. I've given the screw a 1/4 turn (and variations) in, before putting the cap back on. I don't know how many times that I've readjusted the screw, but the cap seems to make a difference. The other antenna had to be tuned by trimming the wire and there were no changes when I put the cap back on.

[prerunner1982]

Yes the cap makes a difference and in one of my Radio Comm Tech tips I mention this and that lubing the cap may be helpful as you will have to take it on and off multiple times. 1.3-1.7 is fine, go with it and be happy.

[GoneWithTheWind]

Yes the cap makes a difference and in one of my Radio Comm Tech tips I mention this and that lubing the cap may be helpful as you will have to take it on and off multiple times. 1.3-1.7 is fine, go with it and be happy.

Thank you! Is there a link or some way I can see/read those tips?

[prerunner1982]

I have posted some in the CB section and have segments on the Jeep Talk Show.

My tips:
1. Make sure the antenna mount has a good clean metal to metal contact with the body.
2. Where the coax attaches to the underside of the mount, make sure it has good clean metal to metal contact there. (Powder coated mounts are a waste of time and money)
3. Get the antenna as high as possible and/or run the longest antenna you can.
4. Check SWRs.

[GoneWithTheWind]

Thank you very much! It looks like I have some reading to do.

[prerunner1982]

As far as why the cap makes a difference, though it's not a conductive material it still changes the characteristics of the antenna, likely changes the impedance slightly. When testing/tuning an antenna you want to do so with the antenna set up just as you were going to use it, in this case with the cap on.

If you tested/tuned your antenna on a front fender lip mount and then moved it to the rear above the taillight it would require re-tuning because the characteristics/surroundings changed.

This becomes fun in the ham radio world where antennas can be 10-100s of feet in the air. If you test an antenna 5' off the ground and then move it to 30' the readings will be different as it is in a different relation to the ground, trees, your house, etc.

[Mudderoy]

http://www.firestik.com/Graphics/tip-on_002.jpg

:link: (http://www.firestik.com/Tech_Docs/Setting_SWR.htm)

[nickyg]

A light coat of common hairspray will help keep the tip in place?? It helps on windy days too.
I picture in my mind a pile of dead bugs and leaves stuck to an antenna.

[prerunner1982]

I don't think spraying the entire antenna is necessary. Only the tip will do. (Spray it inside the cap)

[xj-jake]

Only the tip will do. (Spray it inside the cap)

That's what she said!

[GoneWithTheWind]

I took the antenna mount off and started over. Cleaned off the paint where the mount goes and put it back. Cut off about 10' of coax and about 8" more wire off the antenna. I'm at 1.3 - 1.8. I went for a ride and was able to hear someone on most of the channels I tried, nothing that I wanted to listen to though. I'll go through the archives and see what more I can learn. Thanks!

[prerunner1982]

http://www.firestik.com/Graphics/tip-on_002.jpg

:link: (http://www.firestik.com/Tech_Docs/Setting_SWR.htm)

Yeah... careful with some of their facts. They also claim that you NEED 18' of coax and not to coil your coax.

[nickyg]

They can't put it on the internet if it isn't true. Can they?? I don't know what to do if this ain't true.

http://www.animalplanet.com/tv-shows/finding-bigfoot/lists/10-bigfoot-sightings-last-5-years/

[Mudderoy]

Yeah... careful with some of their facts. They also claim that you NEED 18' of coax and not to coil your coax.

Apparently you don't have to have an EE to build and sell an antenna! :P

[prerunner1982]

They can't put it on the internet if it isn't true. Can they?? I don't know what to do if this ain't true.

http://www.animalplanet.com/tv-shows/finding-bigfoot/lists/10-bigfoot-sightings-last-5-years/

Your safe... that's all true.

[4.3LXJ]

They can't put it on the internet if it isn't true. Can they?? I don't know what to do if this ain't true.

http://www.animalplanet.com/tv-shows/finding-bigfoot/lists/10-bigfoot-sightings-last-5-years/

Where do you think they got Chewbaca for the Star Wars movies?

[nickyg]

where do you think they got chewbaca for the star wars movies?

mind blown!!!!

[4.3LXJ]

What, you never knew?