how to combine 2 jfets into a dual gate fet?

Discussion in 'General Electronics Chat' started by newman123, Nov 23, 2006.

  1. newman123

    Thread Starter New Member

    Nov 23, 2006
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    0
    I tried to buy a dual gate mosfet in Hong Kong, but failed.
    I only obtained several 2N5484 jfets,all of them having Idss small than 3mA.
    is it possible to "cascode" 2 jfets to form a single dual gate jfet?
    i want to use it to make a freq. mixer : 1 gate feed to OL , another gate feed to antenna .
    Jfet and mosfet can do the same job?

    please help!
     
  2. mozikluv

    AAC Fanatic!

    Jan 22, 2004
    1,437
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    hi,

    yes you can, but it's better you show us how you would go about it.

    moz
     
  3. newman123

    Thread Starter New Member

    Nov 23, 2006
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    Actually I want to Diy a simple FM radio by using NE(AD)602/612 as a front end section.
    Unfortunately, I don't have such IC.(it's hard to buy small numbers of IC in
    hong kong.)
    now, what I have is several jfets, general pnp transistors ,lm386 and
    mc1350p.
    the most expansive instrument I got is a $10 digital multi meter.
    is it a easy task to Diy an "acceptable quality" FM radio?
     
  4. mrmeval

    Distinguished Member

    Jun 30, 2006
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  5. n9352527

    AAC Fanatic!

    Oct 14, 2005
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  6. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Hi,

    Getting back to the production of a dual-gate FET from two single units...

    The first step would be to match a pair of FET's. Set up a rig to place each FET into that will allow you to measure the voltage between the drain and a fixed resistor to Vcc with the source grounded and a fixed voltage on the gate. Try to find two that have identical drain voltages under the test.

    Next, you will need to insure both devices run at the same temperature. TO-18 cans may be fastened together with copper wire. TO-92 cases may be epoxied together flat-to-flat. The TO-18's are easier to arrange for pcb mounting.
     
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