Thread: Loading Coil Q
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Old March 23rd 05, 06:56 PM
Buck
 
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Default Loading Coil Q


I have aluminum poles of three diameters, 1.5, 1, and .5 inches. I
have enough of the first two to create a pole of about 15 feet each
and about 8 to 9 feet with the 1/5 inch poles. The poles are no more
than 4 feet long each, but they are able to tuck inside each other, at
least for the same diameter.

What I want to do is to make up a 'kit' with these that I can take to
the field to setup whatever antenna I want to use at the time. For
example, I might set it up as a 20 meter vertical in one
configuration, but in the evening, I might reconfigure it to 75 meters
or 15, or 30 or whatever I desire.

One consideration is to create a high-q coil for it. I am thinking of
using 1/4 inch copper tubing to make a ten to twelve inch diameter
coil so I can match it to the lower bands. I have been reading that
base loaded coils have to be matched to the antenna, but center loaded
verticals are more closely matched to 50 ohms. from what I have been
reading, the center loaded coil requires more turns and a top loaded
coil even more.

A capacity hat is also a viable option.

I am wondering how much I am helping or hurting myself with the larger
coil or if I would be better off with a smaller coil. One thought is
to connect x number of poles, then the coil, then another set of poles
or a whip to make the final adjustment for the match or to match the
antenna by tapping the coil.

I am open to all suggestions, but I am interested in knowing the best
location for the coil and the best size for it.

Thank you

--
73 for now
Buck
N4PGW