Antenna DK7ZB 4 x 4 elements for 144 MHz

I decided for 4 element, 28 Ohm yagi, version "A" (1m boom-length), design by DK7ZB.
It is well descibed on
his web-page.

Mechanical fixing of the two halves of the dipole (radiator) is one of the biggest challenges.
I die-cast both ends by Dentacryl (methyl methacrylate casting resin for technical application), just leaving two solder pins above the surface.

The matching coils (50 Ohm -> 28 Ohm) of all the four antennas.

The matching coil detail. It also provides the symetrization. It is wound by two 37 cm long 75 Ohm PTFE coax cables in parallel.

The splitting cable. For the cable joints the small water-resistant plastic boxs are used.

The detail of one cable joint of the splitting cable.

A special plastics part is used as an element holder.

The bottom view of the same. A special sunken nut is used on the other side.

Large plastics nuts for easy beam tightening. You don't need a wrench, you don't lose the nuts in a grass.

All four antennas ready to go to the mast

Finally, the dream came true.


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