How to solder mini-circuits?

Discussion in 'General Electronics Chat' started by Peter Pan, Jul 25, 2009.

  1. Peter Pan

    Thread Starter Senior Member

    Mar 24, 2005
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    Hello All,

    I need to use MAR-6+ mini-circuit in my design (for first time!) but not sure how to connect its very small leads as each of these has length just about few millimeters and, hence, does not seem suitable for ordinary soldering.

    So, my question is: whether mini-circuits like MAR-6+ are suitable for soldering or their leads has to be connected in some other way?
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    Ah, early surface mount. I used to make 2.135Ghz to 70Mhz down covertors from kits, the transistor (I know, device, since it is more than that) is meant to merge smoothly with a matched impedance line on a PCB. The units I used were good for LNAs and oscillators, in the case of the down convertor the local oscillator was tuned by cutting a non terminated line to a specific length. If you went too far you had to solder a wire on and start cutting it down.

    Basically think something like a 50Ω strip with a ground plane on the PCB board. Where you wanted the transistor you drilled a hole, and soldered it in. From there it is just a matter of biasing the sucker up. Never designed well with them though, kept making better oscillators than amplifiers.
     
  3. bertus

    Administrator

    Apr 5, 2008
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  4. Peter Pan

    Thread Starter Senior Member

    Mar 24, 2005
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    Hi Bertus,

    This's very helpful link indeed. Many thanks. :)
     
    Last edited: Jul 25, 2009
  5. Peter Pan

    Thread Starter Senior Member

    Mar 24, 2005
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    Thank you :)
     
  6. Peter Pan

    Thread Starter Senior Member

    Mar 24, 2005
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    Well, I have managed to solder the leads of MAR-6+ using 8W soldering iron and it works now. One stage amplifier gives more than 20dB gain as shown on picture attached - blue and red traces are time averaged input and output respectively. After some filtering I hope to get rid of unwanted components in spectrum in order to leave the only useful signal, which is at 8 MHz (marked by dashed line on the picture).
    So MAR-6+ does its job quite well!:)
     
    Last edited: Jul 25, 2009
  7. bertus

    Administrator

    Apr 5, 2008
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    Hello Vladimir,

    What is the range you are interested round this 8 Mhz?
    Is it a some khz wide or Mhz?

    Here is a link with some RF tools:
    http://www1.sphere.ne.jp/i-lab/ilab/index_e.htm

    Press the button "TOOLS" on the left to enter the calculator menu.
    There you will also find a bandpass filter calculator.

    Greetings,
    Bertus
     
    Last edited: Jul 25, 2009
  8. Wendy

    Moderator

    Mar 24, 2008
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    Since I make such bad amps (or good oscillators) I would be interested in seeing it.
     
  9. bertus

    Administrator

    Apr 5, 2008
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  10. Peter Pan

    Thread Starter Senior Member

    Mar 24, 2005
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    Hi Bertus,

    Thanks for advice. I will try high-pass filter (which attenuates components with frequencies below 7.5 MHz) shown on the picture attached.
     
  11. Peter Pan

    Thread Starter Senior Member

    Mar 24, 2005
    122
    0
    Hi Bill,

    The schematics which I use is taken from MAR-6+ datasheet (pdf file attached) and is shown on the picture attached as well. I just have used for the frequency range of my interest Cblock=10nF, Rbias=220 Ohms, Vcc = 7 V, RFC (which is optional) is not used, and Cbypass=130pF is used.
     
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