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71885Re: Quick question about winding Transformers

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  • joelweder
    Jan 22, 2013
    • 0 Attachment
      Thanks so much for making these improvements to the build instructions! The algorithm may not be perfect but it's pretty darn impressive!

      Joel VE6EI

      --- In softrock40@yahoogroups.com, "R. R. (Robby) Robson" wrote:
      >
      > I have modified the build instructions such that, in each step calling for
      > the installation of an inductor, I print out an expanded winding
      > instruction. For example, in the step calling for the installation of the
      > T5 transformer in the RXTX
      > Ensemble, the instruction is:
      > "T5
      > XFRMR: 0.6uH: 14T/2x7T bifilar #30 on T25-6 (yellow) 8"
      > Primary: Using approximately 9 inches of #30 wire, wind 14 turns on a T25-6
      > (yellow) ferrite.
      > Secondary: Using a total of 9 inches of #30 wire, wind 7 turns , bifilar,
      > on the ferrite in the same direction as the primary winding. Inductance of
      > the single winding (usually the primary) is 0.60 uH."
      >
      > The instructions are computer-generated and may have rounding errors in the
      > computed wire lengths (e.g., in the above the shorthand version says 8";
      > the generated version says 9"). I conservatively round up.
      >
      > If you are not seing this in the build instructions, please refresh the
      > page in your browser (F5) to remove any cached older pages.
      >
      > I am open to suggestions as to how I should re-program the instruction
      > generation algorithms for more clarity.
      >
      > Since I maintain this website and its associated infrastructure at no cost
      > to the consumer of its instructions and receive no compensation for any of
      > my labors or outlays, I am somewhat limited by my other commitments in my
      > ability to respond as promptly as some might otherwise wish.
      >
      > On Mon, Jan 21, 2013 at 12:54 PM, Alan wrote:
      >
      > > **
      > >
      > >
      > >
      > > ----- Original Message -----
      > > Subject: [softrock40] Re: Quick question about winding Transformers
      > >
      > > > I read that page several times before sending my first email, but it
      > > does not deal with how to interpret this very cryptic
      > > > statement:
      > > >
      > > > 0.69uH: 16T/2x8T bifilar #30 on T25-6 (yellow) 9" (top)
      > > >
      > >
      > > Joel,
      > >
      > > As I've never followed Robby's instructions I'm not familiar with
      > > following them But on the page I linked is:-
      > >
      > > "Specification Format
      > > Winding specs will generally resemble the following:
      > >
      > > 5.0 uH 17T bifilar/34T #30 on T30-2 (red) (19").
      > >
      > > This can be interpreted as:
      > >
      > > a.. Use a T30-2 toroid (color is red and O.D. is 0.3")
      > > b.. You will need two 19" lengths of #30 wire.
      > > c.. For toroids, one turn is a single pass through the center hole.
      > > d.. For binocular cores, one turn is a pass in which the wire goes in the
      > > bottom, comes out the top, goes back in the other hole
      > > at the top, and comes out the other hole at the bottom.
      > > e.. The transformer will have a single, 34 turn, secondary winding of 19"
      > > of #30 wire. Usually the single winiding is wound onto
      > > the core first. Winding should be evenly spaced and ideally cover all but
      > > a 15 degree "wedge" of the toroid. Sometimes, it may be
      > > necessary to wind over the top of existing turns where there is more wire
      > > than there is bare core left.
      > > f.. The transformer will have two primary windings each of 17 turns of #30
      > > wire. The term "bifilar" means to take one of the two
      > > lengths of wire, bend it at the half-point so the resultant "hairpin" is
      > > composed of the two 9.5" long halves, and then twist the
      > > two strands together to make a "bifilar" strand with approximately 3
      > > twists to the inch. The bifilar windings are usually wound
      > > AFTER (and over) the single strand winding. You should wait until you have
      > > wound it correctly before cutting the "hairpin" end of
      > > the bifilar strand.
      > > g.. The inductance value is provided primarily to help validate the number
      > > of turns. It is the inductance of the single-strand
      > > winding"
      > > Which to me seems to give a reasonable idea. And the other links on that
      > > page must give more information.
      > > Once you have done one then it seems uneccessary to repeat the
      > > instructions. It is a one-time learning procedure.
      > > Many others have made the coils before with only a few asking about them.
      > > However, if you feel Robby should make things clearer then I'm sure he
      > > will be glad to discuss it with you.
      > >
      > > 73 Alan G4ZFQ
      > >
      > > >
      > >
      > >
      > >
      >
      >
      >
      > --
      > Cheers,
      > Robby
      >
      > Richard R. (Robby) Robson
      > LTC USA (RET)
      > www.wb5rvz.com
      > www.wb5rvz.org
      > www.rafino.org
      >
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