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Old August 26th 03, 05:55 PM
Ken Bessler
 
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"Richard Clark" wrote in message
...
Hi Ken,

One of several things going on, barring more data.
I have 8-1/2' of rg8x between the
coil and my Z11 autotuner.

How much distance between the choke and the feedpoint? How much
distance between the auto tuner and your station?


Between the choke and the feedpoint is 3 3/4".
Between the Z11 and the station about 6"....


If considerably less then that means you and your domicile are
immersed in the very near fields of the antenna. This complicates
matters and certainly offers the prospects of Common Mode issues
galore (simply through imbalances offered by life in the 'burbs).

How near is too near? For 160M you cannot escape being part of the
radiator by living in the conventional house in a conventional tract.
Higher frequencies only reduce this prospect by degrees. For 20M the
near field, by various assessments, extends as little as 20M away from
the antenna to more conservative expectations of 100M to 200M.

How much does it matter? You seemed to have reduced what Common Mode
issues you could perceive enough. This doesn't mean you completely
removed them, just reduced them below your thresh hold of detection.
So, in that sense, mattering is an issue of detection and if your
neighbors do not detect your activity, nor do you burn yourself on
equipment ground, then there is no "problem."


I rember reading a thread awhile back that suggested one could get
an RF burn even at 5 watts, so I tested for that. I transmitted on all
freqs while touching various points (case screws, Pl-259 cases, etc.)
while I ramped up the freq from 1.8-30 mhz continuos sp. I felt no RF
and saw no change in SWR or power draw when tapping these points.


73's
Richard Clark, KB7QHC


Thanks for the good info, Richard - I hadn't though of near field issues...

72's de Ken KG0WX