Hello and Help!

Discussion in 'The Projects Forum' started by kwf2006, Mar 21, 2008.

  1. kwf2006

    Thread Starter New Member

    Mar 21, 2008
    3
    0
    Im getting into building my circuits, I am entry level at best.

    I have a simple circuit that I have built from a schematic.

    However, I am wanting to know how would I double this curcuit?

    Put two identical circuits in series?

    I dont know where to begin.

    It is supposed to have 0 insertion loss and 0 gain.

    It is used as a rejection enhancement in the IF of a receiver to decrease the bleedover from adjacent frequencies.

    Thank you for any advice or ideas that will point me in the right direction.

    [​IMG]

    [​IMG]
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    What you need to do is post your schematic so that we can see what you are doing at present.

    hgmjr
     
  3. rwmoekoe

    Active Member

    Mar 1, 2007
    172
    0
    i think it's ok for you to put them in series.
     
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Connecting the output crystal of the first stage to the input crystal of the second stage won't work. Add an emitter-follower as a buffer between them.
     
  5. Nomad

    Active Member

    Oct 21, 2007
    43
    0
    if your using this for cb band, i'm afraid you'll be disappointed. most of that bleedover is from crappy chopped up transmitters actually producing output on your desired frequency.
     
  6. kwf2006

    Thread Starter New Member

    Mar 21, 2008
    3
    0
    Thank you for everyones input, I really appreciate it!

    [​IMG]
     
  7. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You're right - I forgot about that.

    There are a lot of "boogered up" transmitters around. Properly designed AM transmitters have modulation limiter circuits built into them, that prevent the transmitter from approaching 100% modulation (where frequency "splatter", or transmitting on a broad band of frequencies, occurs). Ill-informed "hacks" defeat the purpose of this limiter circuit in their attempts to "get out", or transmit longer distances, which is an illegal transmitter modification. They often exacerbate the problem by adding linear amplifiers to their system, which is also illegal.

    If you find one of these clowns, stick an ordinary pin into their antenna's coaxial cable, and clip it off on both sides. That should shut them right down. Then contact the FCC with dates, times, and power levels you observed from their transmissions.

    The first part is risky, but will cure the immediate problem. The 2nd part may take quite a while, but will put the owner of the illegal transmitter in jail for a long time.
     
  8. kwf2006

    Thread Starter New Member

    Mar 21, 2008
    3
    0
    Actually, I am a ham. KB5WVK. The interference is being caused by another ham on the next block over, when he fires up on 20 meters it makes reception almost impossible on my HTX-100. It is a 10 meter only rig, however the circuit design is somewhat like a cb radio. It is not my neighbors fault that I am getting interference, it is my fault for having a poor quality receiver. I know I need to upgrade my equipment, but that is just not feasable at this time. So I thought, why not take this design and try to improve it. After all, im trying to improve the receiver, not hack it for cb channels! The primary circuit above I assembled on perf board and it worked quite nicley. However increasing the amount of db rejection should be possible.

    I agree with the horrible transmitters and QRO on 11 meters. Its a joke.
    The good news is that with our dip in the sunspot cycle, they are pretty much shut down for a while, no dx even with 50 kilowatts :)
     
  9. Nomad

    Active Member

    Oct 21, 2007
    43
    0
    good to see it wont be a wasted effort. maybe i'll hear you on my heavily modified 148 lol. i'm sure wookie was kidding as now days you can get shot or arrested messing with that pin deal. although it works wonderfully. and the fcc is underfunded and understaffed and rarely do anything about 11 meter unless it interferes with something else like emergency services. must have been nice when they actually did something. sigh
     
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