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AM Transmitter from Signal Generator UDB1208

Discussion in 'General Electronics Discussion' started by ElectroPoint, Aug 2, 2017.

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  1. ElectroPoint

    ElectroPoint

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    Aug 2, 2017
    Hi,
    I'm trying to make an AM transmitter. I have the schematics to make it but I was wondering if I could use my signal generator UDB1208 outputting to a rf amplifier outputting to a mic. Would that work? Say 1305khz? I'm new to this stuff.
     
  2. kellys_eye

    kellys_eye

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    You don't 'output' to a mic.... that's the input.

    You can use a signal generator to do it - quite easily if the signal generator has a modulation input.

    But a simple stand-alone AM transmitter is pretty easy to knock up using standard parts - Google 'Pantry Transmitter'.
     
  3. ElectroPoint

    ElectroPoint

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    Aug 2, 2017
  4. kellys_eye

    kellys_eye

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    No, that doesn't have a modulation input but it could be fed to a transmit stage that had one....

    You do realise that you need a special license to transmit on the frequency you mention? You can't just knock one up and hope it works either! Filtering is essential to prevent interference.

    The 'pantry transmitter' I mentioned is designed to radiate at a low enough power level to keep it legal and 'clean'.

    What reason do you have for wanting to transmit on 1305kHz? There are only 4 stations transmitting on that frequency in the UK - it being the 'broadcast band' and off imits to anyone without the appropriate licencing.
     
  5. hevans1944

    hevans1944 Hop - AC8NS

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    The UDB1005 does not appear to have a modulation input. The TTL output is for use in "clocking" transistor-transistor-logic.

    Finland (being a member of the European Union) is bound by Radio Equipment and Telecommunications Terminal Equipment (R&TTE) Regulations that currently forbid unlicensed transmitters of any power output level at any Medium Wave radio frequency. In particular, operation of an unlicensed transmitter at 1305 kHz is forbidden.

    From a practical point of view, assuming you don't mind disobeying the law, very low power transmitters are likely to go un-noticed, provided they do not interfere with existing licensed services, such as amateur (Ham) radio. Hams are quite jealous and protective of their allotted slices of the electromagnetic spectrum. They will likely report you to the Finnish Communications Regulatory Authority (FICORA) if one of them detects your illegal transmitter. Whether that agency actually acts on such a formal complaint depends on a lot of factors, almost none of which you control. So, proceed at your own risk.
     
  6. ElectroPoint

    ElectroPoint

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    Aug 2, 2017
    Sorry about that Like I said, I'm new at this and was just trying it out at a random frequency. I don't know about the regulatory stuff. I saw some other posts on AM transmitters too
     
    Last edited: Aug 2, 2017
  7. ElectroPoint

    ElectroPoint

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    Aug 2, 2017
  8. hevans1944

    hevans1944 Hop - AC8NS

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    Well, the "regulatory stuff" is important more than ever in the 21st Century, because the available spectrum is becoming extremely crowded.

    Back in the day (while still a teenager), I built a low-power AM broadcast band transmitter and put it "on the air" in my neighborhood, at first re-broadcasting the audio of an existing radio station so I could do a "walk about" to find out how much range the transmitter had. Not much: I couldn't hear it more than a few hundred feet away using a portable transistor radio. I didn't know at that time that the NSA (National Security Agency) had very sensitive receivers that could easily record my illegal transmissions from miles away. Nevertheless, I sweated bullets every time I fired that puppy up, fully expecting a visit from the FCC (Federal Communications Commission) enforcement branch at any time. This fear was enough to lead me to abandon and disassemble the transmitter after only a few weeks of experimentation with a friend who lived a few houses away on the same street.

    A few years later, while serving in the Air Force, I obtained a Novice Amateur Radio License (call sign KN8UTJ), built a legal transmitter, and got on the air on the Novice portion of the 80M band, banging away on a telegraph key to improve my Morse Code listening skills... transmitting about fifty watts into a tuned dipole antenna mounted on the roof of my barracks. Never built or operated another illegal transmitter after graduating from high school.

    The Feeltech Chinese DDS signal generator does not have a modulation input.
     
    davenn likes this.
  9. davenn

    davenn Moderator

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    Sep 5, 2009
    no


    I suggest you do some online reading and youtube watching of AM transmitter construction
    and I suggest and has been indicated by others, DO NOT put anything on the air without appropriate licences
     
  10. davenn

    davenn Moderator

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    Thread closed
     
    hevans1944 likes this.
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