CB radio range only 50 feet with home made whip antennas... help!

[Serpentina]

Hello, I am new to CB radios. I have always wanted radios from when I was a kid, and would go to radio shack with my daddy, and look at them, but they were over 100 dollars and I could never afford them.

Recently I came upon 2 used and quite comparable 40 ch CB radios. The Uniden PRO 501XL, and the Radio Shack TRC-502, used $30 for the pair. My best friend and I are planning to use them for when I go out for bike rides. I have set up the Uniden as the home base station, as it is missing its clips and microphone hanger so I couldn't attach it to my bike. The Radio Shack radio I made a super awesome custom paper battery tube (works better than I expected) to power the radio. I plan to use channel 6 mostly for my communication with him.

The problem came to not having any antennas and not having the money to spend yet another 30 dollars for a pair of antennas, that would push me over my limit on this project. I did quite a bit of research when I got the radios to figure out how to make antennas, but there was nothing about making short and relitivly portable antennas that I could find, not being an expert.

Last night I had a dream that showed me how to make an antenne for the radio, I believe its called a whip antenna. Basically I took the 106.5 inches the mast style antenna is in length and I divided it by 4. I took two coat hangers and straightened them out as best as I could. They are pretty straight but not any where close to perfect, I didn't think they had to be perfect. And cut them both down to 27 inches, that is from where I bent it to stick into the connector to the tip.

I don't have any fancy calibration tools, or even a capacitor or a ground wire attached, just the coat hanger sticking out of the back of it. And I took my bike out to test it. I was a little ambitious testing it at first at maybe 300 feet away. My best friend said he heard me a little bit but couldn't make out what I was saying. Only when I was about 50 feet away could we both talk back and forth. He may as well have just yelled out the window to me.

His station is stitting in the middle of the biggest window in my apartment.

What do we need to do to make this work at a better range... we were hoping at least 2 miles, but it would be awesome if we could do more like 8-10 miles.

We are litterally on a shoe string budget, and can only use what we have laying around, which is pleanty of 5 foot or shorter stranded copper wire, more than enough coax cable that he picked up at work when they upgraded their system, a radiator that we could use to ground the base station radio (but I didn't know if it would even do any good, so I haven't yet), and a LOT of time to get it working.

My thoughts are that its possible the antenna are slightly too long? My math told me 26.625 should be the length but I cut them to 27 because it was a lot of work, and better to start long than short. But I am not any where near an expert on this...

My other thoughts are to try to create an indoor dipole, but we don't have a lot of room for one, and I am absolutly no expert on installing one, let alone building one. It would have to work inside, since this is an apartment, and I don't have any wire thats 108 inches long.

What follows are pictures:
Serpentine's Radio Setup - Imgur (the whole album in case the img tags dont work below.)

This is the base station.

Here is a look at the length of the antenna, as best as I could with the lighting

Here is a look at the 90 degree bend where the whip goes into the antenna socket. (its not touching the ground)

Here is the portable radio shack radio

Front view.


Thank you for reading, and for helping me with this project! I am so excited to have radios that are even working at 50 feet, I know we can do better!

Thank you for helping me!

 

[n4yek]

My thoughts are that its possible the antenna are slightly too long? My math told me 26.625 should be the length but I cut them to 27 because it was a lot of work, and better to start long than short. But I am not any where near an expert on this...

For starters, a 1/4 wavelength on CB Channel 19 is 103.3", cutting anything less will not make anything worth while. All CB antenna's you see on vehicles have Loading coil's on them which allows them to be shorter for mounting purposes.

If you are wanting portable radios, you could have spent less money and purchased FRS radios, they probably would have worked better for your use.

 

[WB4CS]

For starters, a 1/4 wavelength on CB Channel 19 is 103.3", cutting anything less will not make anything worth while. All CB antenna's you see on vehicles have Loading coil's on them which allows them to be shorter for mounting purposes.

If you are wanting portable radios, you could have spent less money and purchased FRS radios, they probably would have worked better for your use.

Ditto to what they said ^^^

Also, another problem I see is this... If I'm reading you correctly, you stuck the piece of coat hanger directly into the connector where the antenna goes? It's hard to see in the pictures, but it looks like an SO-239 connection on the back of the radio? If that's the case, that's a major problem. An antenna has 2 parts that is basically the positive (transmit) and negative (ground) side of the antenna. Even if the length of the wire was 104 inches (as it should be) you don't have anything connecting to the ground of the connector, thus not creating an electrical circuit.

I would suggest finding a CB antenna that has the correct connector for the radio. If you want to go the DIY route and want a good base antenna, look online for schematics for a vertical dipole or J-Pole antenna. They're cheap and easy to build, just change the frequency in the calculations for the length to 27 MHz. Or as was suggested, going with FRS radios. The reason for such a long antenna length on CB is it's at 27 MHz. FRS radios are UHF 460 MHz so the antenna lengths are much much smaller. The lower in frequency, the larger the antenna element needs to be.

A+ for trying it on your own, not many people would take that initiative.

 

[KC4RAF]

What with the rig being some what

large for a bike, the wrong thing for an antenna, which isn't correct in any fashion, the batteries won't last long at all, etc. Just like the two previous posters stated, get yourself a couple of FRS radios. They are cheap at Wally World and everywhere else.

 

[mmckenna]

You are very creative, especially with that battery holder. If you are using "D" cells, they usually have about a 4 ampere/hour capacity, which will run your CB just fine. How long your radio will run off this battery pack will depend on how often you use the radio, and how much time you spend transmitting.

The others are correct about the antenna. The 102" whips are quarter wave, so shortening it is not going to work.
You need to find or build an antenna that will resonate at the CB frequencies (around 27MHz). With most designs, you'll need a ground, but that can be accomplished by using the frame of the bike.

While FRS radios would be a cheap and easy solution, it won't really teach you anything. Buying a radio off the shelf, putting the batteries in it isn't very hard. Based on what you've done so far, it really looks like you have the beginnings of a hobby. I'd encourage you to NOT buy FRS radios and keep experimenting with what you have.

Good luck to you! I remember doing similar things when I was young with an old CB, a whip and a pair of 6 volt lantern batteries. It didn't work very well, but it was a great learning experience. Don't give up!

 

[mmckenna]

Oops, looks like those may be AA batteries in your home made holder. They don't have much capacity, so they won't last long, but they'll work for a while.

For the base antenna, I'd suggest researching a "Dipole" antenna. They are really easy to make with some scrap wire and a bit of trial and error.

Actually, Serpintina, why don't you contact me. As a new user you can't use the private message function of this board, and I can't PM you. If you can e-mail me at mmckenna at ucsc dot edu, I might be able to help you out a bit more.

 

[robertmac]

Crappy Band is poor for the use you are intending as has been pointed out above. And then when the junk skip rolls in, it becomes even more of a Crappy Band. As others have mentioned, cheap bubble pack FRS radios for the same price wasted here would probably provided an easier, more reliable and more distance communications.

 

[WB4CS]

While FRS radios would be a cheap and easy solution, it won't really teach you anything. Buying a radio off the shelf, putting the batteries in it isn't very hard. Based on what you've done so far, it really looks like you have the beginnings of a hobby. I'd encourage you to NOT buy FRS radios and keep experimenting with what you have.

While I agree that it sounds like he's on the right path to experimenting with electronics and radios, even Ham Radio operators know when to use the right tool for the job. If I were going biking with a few friends and we wanted to communicate, I'd want to use a couple of FRS radios with VOX headsets, not a large clunky CB Radio with a huge whip antenna and a mic I'd have to hold with one hand while steering the bike with the other. The right tools for the right job.

But I do agree with you mmckenna, he is on the right path. To the OP (if he even comes back to this thread) maybe you should look into studying for your Amateur Radio license?

 

[902]

Serpentina, I love the fact that you are doing stuff and experimenting! I used to do a lot of this, too, and I think it's the best way to learn. What everyone has said is right. CB uses a big antenna. You would need at least a quarter wave and a ground plane to be efficient. How you figure that is: 234 (a constant) / frequency. In this case, your frequency is about 27 (a lot of folks take out calipers, you can, too, but being in the ballpark is fine at this point). That's a little over 8 feet of radiating surface. You've seen those ball and spring antennas, right? THAT's a quarter wave.

Don't let that scare you. Some folks mentioned loading coils. Every bit of that is true, also. You'll see some police motorcycles with antennas drilled into the radio tray behind the rider. That antenna probably has a loading coil on the bottom of it. But there's one more kind. It's a helical antenna. It's the electrical equivalent of a 1/4 wave antenna wound onto a form, and then usually coated with rubber. This is the "rubber ducky" antenna you might read about elsewhere on this website. Since you like experimenting, I suggest you get an SWR meter, because that's important, and then tuning and pruning to the best match.

Yes, FRS will probably work better for you, but it's not as much fun, and you've already put considerable energy into this. You might also want to consider that, since you got the radios used, they might not be 100%. That could limit your range significantly. And, many CBs don't have a lot of protection in their outputs. Professional radios have a power cutback circuit that senses a high VSWR and "folds back" the power. CBs without that kind of circuit will just crank out power until the output amplifier burns out. A deaf receiver may have had power coupled into it, blowing out a transistor in the "front end." These things do happen, and you should probably be aware of them, but they are not very common. You'll see right away on a meter if a transmitter is "putting out" or not. You can also see that with an ammeter connected to your battery lead.

Under ideal conditions, I get a reliable 5 or so miles transmit/receive from a CB. Yeah, you can get more, or you can get a lot less.

You might also want to try a 12 V gel cell. I used to have one to run a (real) headlight on my bicycle.

Best of luck - and NEVER stop experimenting!!!

 

[n4yek]

hmmm...interesting

 

[loumaag]

I have deleted all off topic posts and edited the one that started the nonsense.

Folks, look at the OP, it is his first post here, that means it had to be approved by a moderator. If the moderator felt it belongs somewhere else, it would have been put there before it was approved.

This is the new user forum, it is a place where folks new to the various hobbies supported by this site should feel safe in asking questions, it is not a place where some old crotchety folks get to express what they feel is what someone is doing wrong.

To the person who reported this thread, you were the worst, it is standard policy that we don't move items from this forum; not only was your report wrong, but you were critical in your posting in the thread. To the person who was defending not moving it, you should have just reported the problem, although I appreciate your efforts.

Everyone who thinks they were right and I am wrong, read the following link that has been in place for over 4 years:
http://forums.radioreference.com/ne...forum/137385-zero-tolerance-effect-forum.html

Just be thankful that I didn't just start issuing infractions.

 

[jfhtm350]

CB channel 19 = 27.1850 Mhz

Amateur Vertical Antenna Calculator
103.3" @ 1/4 wave
Frequency Wavelength Calculator
108.6" @ 1/4 wave
Online Conversion - Frequency Wavelength Calculator
108.6" @ 1/4 wave

Why is there conflicting results between these calculators and who is correct? I dont understand that.

 

[robertmac]

Should change the descriptions of the threads as too confusing. Oh where or where to I look for information on CB and Antennas?

 

[KB0VWG]

Its fun experimenting

First off what floor of the apartment are you in and of course the higher the better.
Second see if you can place the antenna close to a window or outside would be better.
Third I would see if you can get at least a 4 amp power supply then you would not have to worry about batteries indoors. I always see those size of power supplies around
Fourth I would see if you can get a magnet mount antenna and mount it on a cookie sheet or something and if possible mount it outside of a window or on top of the fridge.

And finally if you have a high swr reading you signal would be lucky to get out 50 feet. If no swr meter then while tuning the whip the more noise you hear as you tune the lower the swr will become.
73's
kb0vwg
wqoi992

 

[QDP2012]

CB channel 19 = 27.1850 Mhz

Amateur Vertical Antenna Calculator
103.3" @ 1/4 wave
Frequency Wavelength Calculator
108.6" @ 1/4 wave
Online Conversion - Frequency Wavelength Calculator
108.6" @ 1/4 wave

Why is there conflicting results between these calculators and who is correct? I dont understand that.

Calculated by hand using (freq in Hz)(wavelength in meters) = (speed of light in meters/second).

• 103.3" is 1/4 wave for 28.58.. MHz = 10.49 m. (Ham band)
• 108.6" is 1/4 wave for 27.185 MHz = 11.03 m. (CB band)

If I were the OP, I would start with an antenna length at least 108.6" and then shorten as needed.