tolerance of the numbers of turns on the torus



I made some comparisons with the number of turns of the reels indicated in the documentation and the software mini tore calculator.
Compared to the value in nanohenry indicated on the documentation, the value of the measurement and the calculation by mini tore calculator, I have discrepancies. So what is the tolerance accepted?


Coil Details

  • L5,  L7 : 12 turns on T30-6  value on doc 720nh for that mini tore calculator give 14 turns  #2
  • L1, L2, L3, L4, L11, L12, L13 : 9 turns on T30-6 value on doc 330nh for.....give 10 turns    #1
  • L14, L15, L16:  10 turns on T30-6 value on doc 440nh for ...give 11 turns                            #1
  • L17, L18, L19:  14 turns on T30-6 value on doc 750nh for ....give right 14 turns                   #0
  • L20, L21, L22: 19 turns on T30-6 value on doc 900nh for .....give 16 turns.                          #3
Therefore apply the values of mini tore calculator or documentation? 
experience can be the difference.
attention, I was told that the fact that the wire passes through the torus, it counts for a turn
And when we zoom in on the pictures, we find the values of the doc.
Unless a lap or two doesn’t make a big difference? That is MY question.



Hi Gerard,

As toroid Al value can differ a bit by manufacturer, and final value depends also on how closely together the turns are wound, I would be more interested in finding out whether the toroids are measured for value on each one, by sample, or are just wound to a certain number of turns?





Interesting science. Yes the first pass through the hole counts one turn, the second pass will be the first turn to wrap around the outside of the torus.

I don't know anything on mini tore, other estimators are around. Yes winding style in turn spacing matters.

I suggest winding to the designer's specification,  then see if it works. Some may not be critical plus or minus one turn. I imagine the low pass filters at the antenna are carefully optimized.

We can certainly question toroid permeability consistency and our winding consistency,  let's see what we get is true of premanufactured and homebrew ubitx.

73 curt wb8yyy