building an am receiver

Discussion in 'Wireless & RF Design' started by amriths04, Nov 24, 2006.

  1. amriths04

    Thread Starter New Member

    Nov 24, 2006
    8
    0
    hello friends,
    i just wanted to get your advice before i can try this out.
    i intend to build a simple am receiver in a "bread board".

    my idea is to first have an
    1)antenna(about 1m)
    2)tuned circuit(L || C(var)).
    3)this output is given to a double stage (bc 107 bjts), with gain=100*100=10000 so that it is amplified well.
    4)this amplified output is then given to an envelope detector.(using a germanium diode and R and C combination).
    5)this output is then sent to another single stage amplifier.
    6)the output is taken from speakers.

    my doubt is,whether my logic is correct? is there any practical problem in the above steps? or any other alternative?

    thanking you in advance,
    amrith.s
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Hi,

    What you are planning is pretty much a tuned RF radio. They do work, but the fact that everybody uses superhet kind of speaks for itself. Lots more complexity, of course.

    Without a schematic, it's hard to make observations about your reciever.
     
  3. amriths04

    Thread Starter New Member

    Nov 24, 2006
    8
    0
    here is the circuit.
    amrith.s

     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Hi,

    It's going to work, but those 2N2222's are a poor choice for the first RF amp stage. A FET like an MPF102 presents a greater impedance to the antenna tank, and gives more sensitivity. I don't have a link to point you to, but any receiver with a FET front end should give better reception.

    Kinda convenient having only one kind of transistor, though.
     
  5. amriths04

    Thread Starter New Member

    Nov 24, 2006
    8
    0
    thank you,
    that link was really useful.

    amrith.s
     
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