Instructables

CB Radios and Relay Towers

`A buddy and I have portable Citizen Band Radios and we were kinda wondering what cool stuff we could do with it. Also we want to try and build a simple Relay tower to be able to talk to extend the signal. How would we go about doing this?

NachoMahma6 years ago
Sure, but that's for ham radio and they have CB's. True, there is all kinds of cool stuff to do with ham radio, and there are repeater "towers" everywhere all ready especially on the 2 meter band.
. CB _is_ ham radio. 744 hits for CB on the ARRL site.
Citizen's Band (CB) used to be a Ham frequency, but was given to CB'ers in the 70's, much to the dislike of the Hams. Budd
Na CB was created in the late 50s long before it hit the big time in the 70s. Before that craze most people used it as it was intended. Inexpensive short range personal communications
Citizen's Band Radio service was originally 11 meter amateur radio, a favored skip frequency band. Yes, at one time it was a UHF band but as you can read, that was short lived due to high component costs ... those old vacuum tubes just didn't like high freqs like solid state devices do and required special (read EXPENSIVE!!!) construction techniques.


Suggested reading:
http://www.cbcitizensbandradioservice.com/index.htm

static1 year ago
Probably the http://en.wikipedia.org/wiki/Amateur_radio_repeater#Simplex_repeater would be the easiest, Although a full on full duplex repeater would be fun to build. Problem is either would be worthless for local communications when the band is ope. Of course both are probably still illegal to operate in the CB band.
Goodhart6 years ago
Certain days and times of the year, one can bounce the signal off of heavy cloud cover, or with a particularly strong signal (and with a bit of delay, I might add) off the moon. Oh wait, I do believe I am referring to SW, and not strictly CB
VIRON Goodhart6 years ago
It generally takes a lot of power, 1000 watts, and works best for morse code. It might be interesting to see what you Can HEAR by pointing, perhaps, a common rooftop TV/FM antenna at the moon and trying to hear any stations. Forget about the video. A full moon is not the best time because the sun makes static in space, which you know if you watch satellite TV around the equinoxes. It may also be interesting to point the antenna at geosynchronous satellites and try to tune in "different" signals. They should passively bounce more clearly than off the moon.
Goodhart VIRON6 years ago
I have heard some stories (and they may just be that too) of guys doing wonders with 5 watts. But that has to be rare indeed (if they are actually true) and yes, that was with morse code.
CB, 11 meters, used to be a ham frequency until the US government gave it to the public.

Hams loved it because it had the best propagation characteristics of all the Ham frequencies. Get a few more sunspots than normal and you could reach thousands of miles on just a couple watts with even basic equipment, like the bicycle mounted system I mentioned.

That bike also showed the importance of a properly designed and installed antenna. Not far from where I made the Bermuda contact, which was a response to an emergency call, btw, lived a CBer that didn't take time to install his (then) $400 antenna correctly.

He couldn't hear them.

My whole setup, including bike came to under $200.
Oh yes,  I remember now.....when I was a kid, I took a channel 3  half mile walkie-talkie and wired up a VERY long antenna to it, and ran a ground to the heating ducts in our forced air home.....I was "metered" one mile away by a CB'er who said I was pinning his meter (blowing his doors off I think he said) at a base station.   :-)
I believe it. What you did was create a better antenna than the one it came with even if it was probably a poor SWR match.

BTW, my best "trip" with a 100 MW walkie talkie was 5 miles. I was in the National Guard in IN and i was on the second floor fire escape platform of my barracks. On either side of me was a steel ladder about 35 feet long, about one wavelength at CB frequemcies.

My little walkie was engergizing the ladders to make a louder signal, about 5 times louder.

Both cases prove the point that the best improvement for any two-way radio is a better antenna.
Yep, that same antenna allowed me to hear am stations midway across the USA
 
ps: I forgot the mention that the walkie-talkie unit I was using was one of those really cheap ones kids used at the time.
 
Yep. I can remember hearing a staion "skipping n from a long way off and thinking they were local. Budd
O-Budd-13 years ago
The secret of any radio transmitter, from cell phone to the big public AM radio stations is the antenna.

Simply, the better the antenna, the better the range both on transmit and recieve.

Do your radios operate of CB (27 Mhz, 11 meter) frequencies? Do they have a twist-on type jack (BNC connector) for the antenna? If so, get a BNC to pl-239 adaptor and you can connect to any antenna for CB use. Just be sure to check the SWR's of the antenna before transmitting.

Low power ( QRP) range is very dependent on atmospherics and antenna design for contacts beyond line of sight, but it's amazing what you can do:

108" fiberglass whip mounted to the luggage rack of a 10-speed bicycle, battery powering a CB ( Realistic Mini-23 with 4 watts RF output) and I used to talk from central IN to Bermuda on it. back in the mid 70's ... but the skip was really good back then.

Have fun.
VIRON6 years ago
It depends. Do you have 27 Mhz CB like trucks use on channel 19, or do you have FRS or GMRS? Those are newer, smaller kind of CB. Are you in the USA? You can extend the signal legally by experimenting with GOOD antenna designs. For 27 mhz, the antenna will be rather large and as high up as you can get it. For FRS you can experiment with "corner reflectors" or "Cantennas"... or really advanced "Yagis". It's cheaper and better to make a GOOD antenna than to buy one, but it's a very challenging project. A relay station is called a repeater and it consists of one receiver and one transmitter that turns on to ANOTHER CHANNEL when the receiver hears a signal. It might be hard for you to transmit and receive to it on different channels, but it can be done various ways.
VIRON VIRON6 years ago
Pro

Get More Out of Instructables

Already have an Account?

close

PDF Downloads
As a Pro member, you will gain access to download any Instructable in the PDF format. You also have the ability to customize your PDF download.

Upgrade to Pro today!