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7ele homemade DK7ZB yagi for 70MHz

I based the construction of this antenna on the boom, and element mounting of an old defect 2m 15ele CUE DEE yagi

The CUE DEE boom disassembles easy into 4 pieces, making it excellent for portable use

I tweaked the DK7ZB design to fit the CUE DEE boom length (72mm shorter than the DK7ZB design), such that I can re-use the mounting holes for the reflector and the last director. I also found the right element lengths for the 6mm rod elements used with the CUE DEE. The result was as follows:

Element

Element-position 

Element-length (6mm)

Ref

0 mm

2131 mm

Rad

581 mm

2028 mm*

Dir 1

1103 mm

1987 mm

Dir 2

2203 mm

1941 mm

Dir 3

3553 mm

1914 mm
Dir 4 5196 mm 1910 mm
Dir 5 6443 mm 1878 mm

* The dipole is made from 12mm Alu tube. Length is end-to-end, not sum of the two tubes.

The other elements can be cut from two 6m long rods. If you need to cut them for transport, cut both at 4.01m.

4NEC2 simulation NEC2 File

SWR plot

 

Feed point box

Length of matching cables = 300/70.15 (freespace wavelength) * 0.85 (velocity factor SAT752F) * 0.25 (quarter wavelength required) = 909 mm

The finished antenna in action in JO20XC

This antenna activated the following sqaures: JO56PA JO66BA JO44IW JO20XC JO64GX JO74MX JP40KS

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