variable cap question

Discussion in 'General Electronics Chat' started by lokeycmos, Jul 25, 2011.

  1. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    432
    7
    i was on you tube trying the fm radio aircraft radio hack. i noticed that on the back of the cap there are 4 screws. is there actually 5 variable capacitors in one? they seem independant of eachother.
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,638
    2,344
    Hello,

    The little screws on the back of the capacitor are fine tuning screws to adapt the LO signal to the RF-input signal.

    Here is an example of a two capacitor tuning capacitor
    [​IMG]

    Yours has 4 capacitors inside with 4 finetuning screws.
    2 (small ones) are for the FM or AIRband. the other 2 are probably for the AM bands.

    Bertus
     
  3. RRITESH KAKKAR

    Senior Member

    Jun 29, 2010
    2,831
    89
    Absolutely, Right even few year back when i was also Interested in listening FM,etc...

    when you will rotates 2 screw of of FM you will notice one of them will shift the whole freq. band of FM station:-
    e.g.: Let we rotate the srew in clockwise the channel coming in that position may be shift to forward or backward direction....

    and other is for clearly reception ( i think..!!)
     
  4. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    432
    7
    interesting, you learn something new every day! not having much luck with the airband hack. the local stations are overpowering the airport 10 miles away. fyi this is what im doing http://www.al-nasir.com/www/PVA/Library/Docs/radio_comms.shtml

    i failed to mark default settings so the radio is pretty messed up lol!but it was a great learning experience till i find another radio! thnx
     
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