8 turns with 22 gauge coil .

Discussion in 'General Electronics Chat' started by Fmrx, Jan 28, 2015.

  1. Fmrx

    Thread Starter New Member

    Jan 28, 2015
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    I tried to do a coil with 28 and 26 gauge never even flicked the fm band went slowly tuning still nothing .put my finger on out put feel a little heat which I know is working .ok I'll get straight to the point on the schematic it explains use 22 gauge for 8 turns for air coil .i tried this for 26 and 28 gauge never worked .do I need more turns as it's different swg ? I've spreaded coils closed them together not a thing .?
     
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
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    what is the diameter of the coil supposed to be? that maters too.
     
  3. Fmrx

    Thread Starter New Member

    Jan 28, 2015
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    Hi here is a picture of the coil with diameter he means a ball point pen which I don't have a clue in measurements there so I used a 8mm drill bit .and also tried a 4mm drill bit .
     
  4. ian field

    Distinguished Member

    Oct 27, 2012
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    Sounds like a Band II FM bug - there's quite a lot of those floating about the internet, some of them for kits with a PCB incorporating a spiral track inductor.

    As someone else mentioned, the air coil diameter matters, and sometimes you also have to stretch out the turns for a specific length as well as diameter.
     
  5. Fmrx

    Thread Starter New Member

    Jan 28, 2015
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    H
    i ian thanks for reply there .yea there seems to be same schematics on Google dunno if it's market crap or what .but thought I would give it a go see how it went i new soon as I felt the output it's working but getting that coil was beyond me .i stretch the coiled wide as while tuning no joy at all .on a picture what is the diameter I would use to correct that issue ive used a 8mm and 4mm bit no luck at all .
     
  6. ian field

    Distinguished Member

    Oct 27, 2012
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    If you transmit at 10.7MHz - they can't tune you out.
     
  7. Fmrx

    Thread Starter New Member

    Jan 28, 2015
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    10mhz is where I'm thinking its landed on lol .another 70megs upwards would be nice to know it touches that band .so what is the diameter for that ball point pen he used as I don't have one . For my 26 or 28 gauge . It uses 5-30pf in parallel with the 8 turn coil .
     
  8. ian field

    Distinguished Member

    Oct 27, 2012
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    The FM bug circuit usually has an RF transistor with a small capacitor from C to E (usually about 5pF), without that it probably won't oscillate at all.

    Exactly 10.7MHz would put it in the IF strip - that's why it can't be tuned out.
     
  9. Fmrx

    Thread Starter New Member

    Jan 28, 2015
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    Spot on ian .i just double checked over that schematic there I did forget to put in the 4.7pf from colecter to the emitter .how did you guess it was that ?. I don't have a 4.7pf .if I put two 10pf in series I'll get 5pf should that work ?
     
  10. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Did I have a stroke or walk into the middle of a conversation or is there more to this thread like a post zero? o_O
     
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  11. Fmrx

    Thread Starter New Member

    Jan 28, 2015
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    Must say never building a crap transmitter like that ever again .the audio was poor out of 10 im giving it a rating of 1 absolutely rubbish quality
     
  12. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Best thread ever. Excellent example of engineer-speak. "I know I didn't say what I meant but he answered my question so it was good enough"
     
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  13. Fmrx

    Thread Starter New Member

    Jan 28, 2015
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    He answe
    he answered the question yip .so as I saw it ripping through the whole dial I was like in the bin with that lol
     
  14. joeyd999

    AAC Fanatic!

    Jun 6, 2011
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    They've been talking in code all afternoon. I tried my best to follow...failed miserably.
     
  15. Fmrx

    Thread Starter New Member

    Jan 28, 2015
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    Well if they talk in code then you should try achieve and join them
     
  16. joeyd999

    AAC Fanatic!

    Jun 6, 2011
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    I understand the words they are using just fine. Not being a radio guy, I just can't figure how they all fit together into such an obviously complete picture.
     
  17. Fmrx

    Thread Starter New Member

    Jan 28, 2015
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    Well imthTs the world of a emateur radio well thimeres a lot of good guys out there who give me good schematics there from amateurs there as much as a hobbiest as I am .
     
  18. joeyd999

    AAC Fanatic!

    Jun 6, 2011
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    Say again?

    Edit: Sorry, your signal is breaking up...I can't hear you...
     
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  19. Fmrx

    Thread Starter New Member

    Jan 28, 2015
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    Lol .swr must be going out the window .i was saying that's the world of amateur radio there your friends. And I was saying I have a few good friends on amateur radio .who do schematics for me as I'm a hobbiest and just like there hobbiest too and keen to learn new things
     
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  20. ian field

    Distinguished Member

    Oct 27, 2012
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    For values up to about 10pF or so you can use a "gimmick" capacitor - two short lengths of insulated single core wire twisted together.

    If you also have the means to measure signal strength - you can tune for maximum smoke.
     
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