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art wrote:
At first I was considering the actual wire length in the braiding b ut that influence became little compared to the current pertabutations. Sounds like you are working on a self-resonant coil and need to know the length of time for the current to flow from end to end. Both sides of the argument are wrong on that one. The current does not jump from one end of a coil to the other in a very small number of nanoseconds as one "expert" has asserted which implies a VF close to 1.0. Neither does the current follow the wires directly round and round the coil as asserted by the other side which would imply a VF around 0.01. The actual measurable VF of a coil seems to be just about double the round-and-round argument side as there is indeed some coupling between adjacent coils. A typical 75m Texas Bugcatcher 6" dia, 6.5" long, 4 tpi coil has a VF of around 0.02 making it about 40 degrees long at 3.8 MHz. -- 73, Cecil http://www.w5dxp.com |
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