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Old May 1st 09, 10:50 PM posted to rec.radio.amateur.antenna
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First recorded activity by RadioBanter: Mar 2007
Posts: 3,521
Default Dish reflector

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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