Build CB Transiever

Discussion in 'The Projects Forum' started by RepublicanRF, Jul 31, 2011.

  1. RepublicanRF

    Thread Starter New Member

    Jul 31, 2011
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    0
    Hello all,

    I have been interested for sometime in building my own CB radio transiever but I'd like to do so with solid state components. I've found multiple AM/FM/World Band SOC recievers & transievers but i cannot find one for the CB (USA) band. I'm assuming this, but being as you can by handheld, self contained CB radios (where all of the components are basically in the mike) surely someone is manufacturing these. Below are two links: the first is to a manufacturer of the AM/FM recievers that are examples of what I'd like to find a CB transiever in. The second link is just an example of a midland handheld CB radio --- I cannot imagine that the analog components are inside of here --- if you know different though please correct me.

    So my main question is: Does anyone know of a manufacturer that makes CB radio system-on-chip transievers? All suggestions are welcomed.

    Thanks in advance for all of your help.

    SOC AM/FM recievers
    http://www.silabs.com/applications/audio/Pages/AudioSystem.aspx

    Midland 75-822 Handheld CB Radio
    http://cgi.ebay.com/MIDLAND-75-822-...637862295?pt=US_CB_Radios&hash=item35b3167d97
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    Unless you have a Amature radio liscense you will not be allowed to build one legally at full power (5W).

    I've built plenty when I was a teen in the 100mw power range, basically a simple crystal and transistor will get you on the air.

    Given that they are commonly available and reasonably cheap, why not buy a legal unit?
     
  3. RepublicanRF

    Thread Starter New Member

    Jul 31, 2011
    4
    0
    Bill,

    I have a couple of good store bought units. I just want to build one. The ones that you've built - with a crystal and transistor - could you tune them to more than one channel?
     
  4. John P

    AAC Fanatic!

    Oct 14, 2008
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    I think that on the build versus buy scale, this one is way down at the "buy" end. Spend a few bucks to get a commercial unit, then pay yourself back by working at minimum wage, and you'd still come out ahead in terms of the time it would take.
     
  5. RepublicanRF

    Thread Starter New Member

    Jul 31, 2011
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    its not about the money or saving time.... It's about my interest in the project.
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    Changing channels on these units is simplicity itself, use a different crystal. The crystal determines frequency.
     
  7. Papabravo

    Expert

    Feb 24, 2006
    10,144
    1,791
    Since the 11-meter CB band is not an amateur band, why would you need an amateur radio license to build a CB transceiver. BTW, IMHO even an Extra Class License does not require any great knowledge of circuit design or construction techniques. What a CROC if true.
     
  8. Wendy

    Moderator

    Mar 24, 2008
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    Rules may have changed over time that I am not aware of, but there is (was?) HAM frequencies right next to the CB band. It was a source of linear amps, which was a major headache for those who were legit.

    It is illegal to build and operate a CB (unless you keep the power very low) to the best of my knowledge. Except for certain critical frequencies the FCC does allow for very low power transmitters.

    CB is considered to be the 11 meter band, and is not open to Hams far as I know. The 10 meter band (28Mhz and above) is open for Hams. The problem is that they are close enough that what works for one will work for the other.

    Back in the mid 70's, where most of my experimentation was being done, their were radio control channels in the 27Mhz region. This has been changed and is now illegal, except for small toys.

    To the OP, I don't think you are going to get much help here, unless you choose to get a technicians Ham license. It is against the terms of service to assist in illegal activities, which this is.

    Commercial radios go through a rigorous set of tests to keep them legal and on the up and up. A home brewed setup can't keep up.

    I think I can discuss theory OK though, CB channels support upper and lower sideband with suppressed carriers, which is very advanced AM theory.

    Receivers are generally always legal, with certain exceptions.
     
  9. RepublicanRF

    Thread Starter New Member

    Jul 31, 2011
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    Thanks for the info
     
  10. wayneh

    Expert

    Sep 9, 2010
    12,126
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    Are you referring to radar detectors? I think that's the only law that ever interfered with FCC wishes that the entire spectrum is free to "listen" to.
     
  11. Wendy

    Moderator

    Mar 24, 2008
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    It was one of the things I was thinking about. I've never been sure states have the right to ban them outright, but then who is going to fight it?

    Another exception is services that expect pay for their broadcast, the measures/countermeasures game between satillite providers and crackers has never ceased to amuse.

    Yet another exception is specialized government channels. Given our government has restraints on the basics as far as I know you are not allowed to repeat what you hear (or see) assuming you have cracked their security. I could be wrong about that one though.
     
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