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Two-way radio convert to short-range radio?

Discussion in 'General Electronics Discussion' started by Solidus, Jun 21, 2012.

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  1. Solidus

    Solidus

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    Jun 19, 2011
    Okay, for introduction on the topic, I'm a DJ and music producer, and will be starting college this fall. This is the era of not much exposure to the unheard of, so I need a way to get an exposure base.

    If it needs to be said to continue, everything I detail here will be crosschecked for legality, as I don't intend to operate on any unauthorized bands.

    What I was wondering about doing is converting a two-way radio (a walkie-talkie) into a short-range, "pirate" (loosely) radio. Obviously, one unit would be the send signal, and anyone wishing to receive would have to purchase their own unit and dial in to the correct frequency (which for the most part are standardized as channel numbers).

    Question is, how would I rig the two-way radio to accept a headphone (3.5mm) or a 1/4" TRS plug for connection to a DJ mixer, etc.? Also, how would I modify the circuitry to allow for a constant power source rather than batteries?

    Also, would it be possible to (simply) modify the unit to eek out a bit more range? It wouldn't need to be anything more than 3-4 miles (5-7km).
     
  2. donkey

    donkey

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    Feb 26, 2011
    working with 2 ways i can tell you now they have headsets already. the added bonus is you can modify these really easily

    as for power they have that too. the only issue is that if you leave the device turned on while connected to mains they get whats called battery memory effect. if you intend to use them continually connected to power this shouldn't be an issue.

    as for range it is defined by the handset used.

    there are legalities to the range you can use and output power. also there is a HUGE legality if the frequency is used for mergency purposes(most of them will be)
    simply put is this possible answer yes
    totally correct answer though is yes... but expect a nice fine if you try it
     
  3. davenn

    davenn Moderator

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    Sep 5, 2009
    and if we really want to be seriously picky about legalities

    there are only 2 bands where music can be transmitted legally
    the AM band 560 - 1640 kHz and the FM broadcast band 88 - 108MHz
    Both require licences unless the transmitter power is under ~ 1 Watt depending on the country the max can be as little a 100mW

    so your thoughts to use some form of tranceiver immediately infers using transmitting music illegally on a band that it isnt allowed and you are likely to upset legit users
    Who I can guarantee WILL take action to stop your activities

    Dave
     
    Last edited: Jun 21, 2012
  4. Solidus

    Solidus

    349
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    Jun 19, 2011
    I would be using one of the consumer hand-held walkie-talkies to do so. Simple channel selection - that way I can avoid a tap on emergency freqs.

    Also, these things are pretty much limited to 2 miles (best case scenario) as they are in the range of mW output.

    Would the conversion of one of these walkie-talkies (without the headset) just be as simple as desoldering the microphone and soldering to/on a TRS female connector for input? Also, would a coaxial connection (standard coaxial cable) transmit the power to an antenna adequately or would I need another form of antenna because of losses due to things such as resistance?

    And Dave, the transceiver I'd be using is already tuned for those allowances for power and band in the US, and unless our FCC has made rules otherwise (which through extensive research I haven't come across yet) there is nothing regarding transmission of music. Of course, there always is unauthorized broadcast if you do not own the rights, but as this channel would be used for broadcasting only what I produce (my own original work), I would have the rights to broadcast and do as I see fit with that part of the question.

    Is converting a CB radio another viable option in terms of power? CB radios in the States are not regulated or requiring of licenses.
     
  5. donkey

    donkey

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    Feb 26, 2011
    just because they are commercialy available does not mean they are not emerncy channels. in certain areas they use the uhf band (walkie talkies use this band too) when there is no cell coverage to call the emergency services.

    my advice is call up whoever monitors this area of broadcast in your country and get a full run down on legalities.

    just a side note though is if you simply plug a 3.5 or any other plug into the microphone you will still have to press the ptt button(press to talk)
    If you really want to make music and broadcast it, try an internet radio station. yes there are prices to pay, but its legal and people further than 2 miles might be interested
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Another issue is that many bands are licensed (or allowed) on the basis that you will be sending relatively short transmissions. Broadcasting is another thing entirely, where you monopolise a certain piece of spectrum in a given geographic area determined by transmitter power and antenna design.
     
  7. Solidus

    Solidus

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    4
    Jun 19, 2011
    Well yes, all this is fine & good, but the root node of the original question was how to accomplish this, not the legal implications of doing so and utilizing it.

    I believe I said it above, but I know that I am responsible for the legal implications of what I create and how I use it; as such I am investigating myself into how to do it in the most legal fashion possible. Gunsmithing is legal. Carrying your gun in public and brandishing it at people, however, is not.

    Half of my interest in doing such is my interest in mechanics and electronics - "physical" methods if you will - I know I can pay internet radio sites to get my own space and host that way, but that takes a lot of the fun of thinking, constructing, and testing away, and the "live" component is lost (I'd have to pre-record anything to do, and upload it at a later time).

    All that being said, I was planning on soldering a female 1/4" (~6.25mm) TRS jack to the microphone connection as well as desoldering the manual PTT button and rigging a toggle throw for constant transmittance. Would this fly?

    Also, would lengthening the antenna produce any viable increase in transmittance range / signal quality? Or will the extreme low power of the unit (500mW max) and its transmittance capabilities be swamped by any significant increase in antenna size?
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    A decent legal way of doing what you want to do is to stream your music from a computer and set up a WIFI access point to broadcast your stream.

    With legal power it is easily possible to broadcast over a large range (I was part of a network where I was around 20km from such a node).

    For reception at long distance, the receiver requires a significant antenna, however at closer ranges you do not (or you only require something simple).

    We used horizontal polarisation because most of the other signals in this band tend to be vertically polarised. This means less mutual interference which is good for you and for them.

    I don't believe you can separate the legal implications from the "how". There are lots of things we could discuss if that were the case. In my country it's called "conspiracy to commit an offence" in some cases, although these days that is shortened to just one word.
     
  9. Solidus

    Solidus

    349
    4
    Jun 19, 2011
    Well yes, I know there are more legally-legitimate ways of doing what I want to do rather than modifying a 2-way walkie talkie and shimmying through some legal gray zones to transmit, but none of that gets me the thrill of actually getting to build something; to wire something; to test it; to see if it works. Probably what will end up happening is I will forget all about it while I'm off at college, but it's the building and the learning about how things work that I'm after. With a Wi-Fi access point, I plug in a few cables, add a screw-on antenna and Bam! I'm done. No learning about wiring or circuitry, which is what I'm after.

    And I understand about the whole "conspiracy to commit a crime/offense", but at least under my country's definition of such you have to know what I plan on doing is undoubtedly a crime, and you also have to instruct me on how to do it. Telling me if I'm doing a general concept the right way and warning me against it in the meantime falls more under freedom of information, which secures freedoms for information if used in a hypothetical and for-knowledge sense.

    But, I understand that I won't be getting any further with this, so it's time for me to wire it like I think it should be wired with basic circuitry knowledge, and then play the game of "I hope it works".
     
  10. JMW

    JMW

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    Jan 30, 2012
    What part of "not legal" don't you understand? The reason being is there are no "clear" channels in the commercial bands period, they are ALL shared. Therefore you will be stepping on someone else. Doesn't make any difference if it is your local Fire Department, Joe the Plumber, or a Pilot, they all share the limited airspace. So what do you do. There are plenty of 1/2 watt FM transmitters and schematics available. When you get to university they might even have a station on campus.
    If you still want to pursue this, try the HF bands, I have no idea how to set up a station, but it can be done.
     
  11. davenn

    davenn Moderator

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    Sep 5, 2009
    thread locked

    we are not going to help with illegal activities

    Dave
     
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