is there any alternate for this!

Discussion in 'Wireless & RF Design' started by aj_silverthunder, Nov 13, 2009.

  1. aj_silverthunder

    Thread Starter Active Member

    Jun 6, 2009
    116
    0
    is there any substitute or alternate for ferrite to make RF choke.because ferrite is not available in my city,so please any one help me!
     
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    What frequency are you designing for? What is the application of the inductor?
     
  3. steveb

    Senior Member

    Jul 3, 2008
    2,433
    469
    The only one I know is air-core.
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,649
    2,348
  5. Papabravo

    Expert

    Feb 24, 2006
    10,173
    1,797
    Yes, you can use powdered iron. It has different properties than ferrite. I'm guessing it won't be available in your city either. Mail order is your last hope. You have not disclosed your location so it is hard to know how to help you. Maybe if we knew where you were some member could advise you on your problem.

    BTW is enammel coated magnet wire available to you? The enammel insulation is critical to making inductors. If the turns are shorted together then the inductor won't be worth much as an inductor.
     
  6. ELECTRONERD

    Senior Member

    May 26, 2009
    1,146
    16
    Ferrite cores have better permiability than powdered iron cores. Except powdered cores are better, if your application requires significant heat dissipation.

    Austin
     
  7. aj_silverthunder

    Thread Starter Active Member

    Jun 6, 2009
    116
    0
    i want to use the RF choke for a RF power ampilifier,which amplifies signal in a range 50MHZ -150MHZ.please help me
     
  8. aj_silverthunder

    Thread Starter Active Member

    Jun 6, 2009
    116
    0
    guys can anyone help me to learn "how to make RF choke on a resistor and how it works,how to make one practically"
     
  9. Papabravo

    Expert

    Feb 24, 2006
    10,173
    1,797
    Sorry, I only know how to find websites that make the materials that I need, order them online, and purchase them with a credit card or PayPal. I have not been able to purchase materials for electronics in a retail establisment in more than 2 decades. I'm pretty sure they don't exist anymore. I know less than nothing about India, having never been there. The directions for winding enammel coated magnet wire around a resistor are on the web and not difficult to find.

    Your chances of successfully building an RF power amplifier for those frequencies without a substantial investment in equipment are remote at best.
     
  10. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Measure the diameter of the resistor body. That gives you the ID of the coil. Use a calculator formula to give the number of turns of the gauge of enamel wire you are using. Solder to one lead of the resistor, wind on the required turns, and solder to the other lead.
     
  11. Papabravo

    Expert

    Feb 24, 2006
    10,173
    1,797
    Once again the wire used for winding coils needs to be insulated. Enammel coated magnet wire has the best chance of being able to meet your requirements. Also note that the resistor will be in parallel with any inductor that you construct in this fashion. It may or may not be appropriate in a power amplifier. I tend to think not, but that is just my opinion.

    On another matter, the value that comes out of a calculator depends on many assumptions. You should know what those assumptions are. Even so you will need to verify those results by measuring the coils that you construct on an impedance bridge or other instrument that is appropriate to the VHF frequency range.
     
  12. aj_silverthunder

    Thread Starter Active Member

    Jun 6, 2009
    116
    0
    doesn't the resistance of the resistor which i use to make RF choke affect the whole circuit!
     
  13. aj_silverthunder

    Thread Starter Active Member

    Jun 6, 2009
    116
    0
    please tell me any website where i can learn to make RF chokes around resistors
     
  14. Papabravo

    Expert

    Feb 24, 2006
    10,173
    1,797
    Yes of course it does. That is why you need to use the technique only where it is appropriate. Like where the R is ten times reactance of the L at the frequency of interest. The impedance will be R in parallel with the L
     
  15. aj_silverthunder

    Thread Starter Active Member

    Jun 6, 2009
    116
    0
    in a place of a rf choke(ferrite core) is it best to use aircore inductor or the inductor made around a resistor!!
     
  16. aj_silverthunder

    Thread Starter Active Member

    Jun 6, 2009
    116
    0
    is it best to use RF chokes made up of aircore inductor or else inductor around the resistor.
    and another doubt is ,assume i want a 500nH RF choke(ferrite core),but can i replace it with a solenoid inductor of 500nH value,will there be any problem!
     
  17. Papabravo

    Expert

    Feb 24, 2006
    10,173
    1,797
    I can't answer that question in general. A schematic diagram would be helpful.
     
  18. Papabravo

    Expert

    Feb 24, 2006
    10,173
    1,797
    The answer to these questions depends entirely on what you are trying to do. The answers you seek are not unique. Again a schematic would be helpful.
     
  19. aj_silverthunder

    Thread Starter Active Member

    Jun 6, 2009
    116
    0
    here is the schematic,there u can see the F1 and F2,the designer says the parameters for the both are : F1 = F2 = 18turns/0.5mm/2.5mm/ferite.
    so if we calculate the inductance ,the result will be 30nH.so tell me can i use a solenoid air-core inductor with a value of 30nH,instead of ferrite core.will there be any major problem or please give me any advise!
     
  20. aj_silverthunder

    Thread Starter Active Member

    Jun 6, 2009
    116
    0
    here is the schematic;;
     
Loading...