Ray,
I made a 40M rotary dipole and followed Force 12's Tornado loading coil
design. They issued a study
on the evolution of their loading coils from Tom Schiller's original
design. They first went to a smaller diameter (less efficient) coil and
later back to a larger diameter final version they call their Tornado
coil. It is interesting
to note that with their new Tornado coil they went back to the larger
diameter coil as Tom Schiller used.
The Tornado design coils are now used on all their coil loaded antennas.
I thought this might be interesting to you on designing the 80M coils.
http://www.force12inc.com/content/Application%20Note%20-%2040m%20Delta%20Coils%20Overview%20DRAFT%202.pdf
Bob
K6UJ
On 10/10/16 9:03 PM, Ray Benny wrote:
I am building a 90 ft, 80m rotatable dipole. I am near the point of fabricating
the inductors/coils that will go about 23 ft out on the element. I am guying
the element just before the inductor. I have several questions:
1. Does the size of the gap between the center element and element tip make
much difference? Is one inch enough, or should it be almost the same size as
the coil length?
2. Is there advantage of winding the coils of copper vs. aluminum? Is it worth
silver plating the copper windings? I'm most likely planning to use 1/4" tubing
either way.
3. Once I figure out the total length of the element, a friend is going to run
EZNEC and tell me the inductor valve I need. I will use a calculator to compute
the physical dimensions of the coils. What is the advantage of building the
coils on either 3 inch vs. a 4 inch form?
Is there anything else to consider in the construction of this antenna?
Tnx for your thoughts,
Ray,N6VRLocated in central AZ
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
|