questions about working with a radio

Discussion in 'General Electronics Chat' started by 55627, Nov 25, 2005.

  1. 55627

    Thread Starter New Member

    Nov 25, 2005
    2
    0
    how can i change the frequency of a old radio?
     
  2. Sebi

    Well-Known Member

    Sep 24, 2005
    59
    0
    Be more specific: AM or FM. tube or transistor radio? Sematic available?
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Hi,

    The front end of all radio receivers is a selective tank circuit. The varable element may be either a capacitor or an inductor. At the same time, a local oscillator tracks with the tuning in order to beat with the selected frequency to produce the intermediate frequency.

    To change the frequency band the old radio operates on would mean reengineering the selective element and the local oscillator. It might be difficult without some test equipment. See information on "superheterodyne radio" for more details.
     
  4. 55627

    Thread Starter New Member

    Nov 25, 2005
    2
    0
     
  5. Sebi

    Well-Known Member

    Sep 24, 2005
    59
    0
    FM... i mean You need to change range from CCIR to higher band?
    If the tuning element is variable capacitor (dual: one section for mod.one for osc.), for receiving the higher frequencies need to change the tank coils.
    As beenthere mentioned, need some reverse engineering if the sematic not available.For increasing the freq. decrease the inductivity: decrease the number of windings (coarse) or put Al or Cu core into coil. Without measuring instruments need big experience for good result.
     
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