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Jim Kelley wrote:
Here is a photograph of a directional wattmeter converted to measure current on W8JI's web page. http://www.w8ji.com/building_a_current_meter.htm IT DOES NOT MEASURE FORWARD AND REFLECTED CURRENT! IT ONLY MEASURES TOTAL RF CURRENT! That's exactly why w8ji "measured" a 3 nS delay through a 100 turn, 10 TPI, 2" dia loading coil. Dr. Corum's formulas predicts a velocity factor of 0.033 on 4 MHz for w8ji's coil. That would make it 37 degrees long with a delay of 26 nS. W8JI "measured" a 3 nS delay because the standing wave current that he used for the measurement does not change phase relative to the source phase in a wire or in a coil. Do you really believe that RF current can travel through 53 feet of coiled wire in 3 nS? Doesn't 26 nS make a lot more technical sense? -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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