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Owen Duffy wrote:
Thinking some more about it, my current thinking is that my analysis was flawed. I was using the standing wave currents, when I should be using the travelling wave components. That's exactly the flaw committed by w8ji and w7el when they tried to measure the delay through a 75m loading coil using standing wave current which doesn't appreciably change phase through a loading coil or through the entire 90 degree length of a monopole. Using standing wave current, w8ji measured a 3 nS delay through a 10 inch long coil, a VF of 0.27. http://www.w8ji.com/inductor_current_time_delay.htm W7EL reported: "I found that the difference in current between input and output of the inductor was 3.1% in magnitude and with *no measurable phase shift*, despite the short antenna... The result from the second test was a current difference of 5.4%, again with *no measurable phase shift*." Of course, phase shift is not measurable when one is using standing wave current with its almost unchanging phase. EZNEC supports that assertion. Bench measurements support that assertion. When traveling waves are used to measure the delay through a 75m loading coil, the correct delay through w8ji's 10 inch coil turns out to be about 26 nS (~37 degrees) at 4 MHz with a more believable VF of 0.033. http://www.w5dxp.com/current2.htm -- 73, Cecil http://www.w5dxp.com "Government 'help' to business is just as disastrous as government persecution..." Ayn Rand |
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