Hi Folks,
Thanks to Steve Weber for his prototype photo of the folded conical helical
antenna on the link below:
This is with the one monopole mounted, and ready for more to be wound. I
really appreciate his doing this intermediate version, as the four monopole
version gets the turns so close together, a picture does not show clearly
what is going on. It is not too clear with the insulation on the wires and
same color; but the wire toward the slant edge is the no. 10 here, and the
wire toward the central axis in each turn, is the no. 12. At the bottom,
the no. 10 goes to coax shield, the no. 12 to coax center lead.
A few notes about this pair of pictures. The Cone will not normally be used
in this configuration, it MUST be over a radial plane or ground plane screen
at least 6 feet square to work properly. The wide end of cone must be up
and small end closer to ground.
The Monopoles must start witht the short, (fold) at the wide end. This wide
end is 16 inches diameter for either 10m model or a 20m model. The vertical
axis where the coil supports join should be 13 inches high.
The slant length of the supports over which you drill holes should be 12
inches long first turn to last.
The end of the monopole at the narrow part of cone must go to coax without a
balun, and the coax connections must go straight off the narrow end of cone
and through the ground screen before making a right angle turn as shown
here.
Remember the wide end is parallel to ground, and ground plane. Notice the
holes predrilled in between turns for the second monopole to be threaded.
In a similar manner, for optimum performance and match to 50 ohms, you
should have one turn pair of the first monopole, then allow 3 pairs of holes
for the other monopoles. Thus, when all are threaded, you have a pair
terminated at the top of the cone wide part, and then wind the next pair
starting 90 degrees from the first start, and so on, so each succeeding pair
is below the pair above, pair 1, 2, 3, 4. Since they start 90 degrees
apart around the wide part, they should end 90 degrees apart around the
narrow end, but you are going to solder all the no. 12's to coax center
lead, and solder all no. 10's to coax shield and ground screen, (or
radials).
Now that you have a picture, if you have any questions, please write:
<k5kvh@arrl.net>
http://www.qsl.net/kd1jv/cone.HTM
begin 666 cone.url
M6T1%1D%53%1=#0I"05-%55),/6AT=' Z+R]W=W<N<7-L+FYE="]K9#%J=B]C
M;VYE+DA430T*6TEN=&5R;F5T4VAO<G1C=71=#0I54DP]:'1T<#HO+W=W=RYQ
M<VPN;F5T+VMD,6IV+V-O;F4N2%1-#0I-;V1I9FEE9#U",#$X.3%#.#DS135#
',3 Q-4(-"@``
`
end
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