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Large yagi

Apr 23rd 2017, 22:02

SIZE358

Joined: Apr 19th 2009, 19:30
Total Topics: 0
Total Posts: 0
On the k7mem yagi design page using the arrl spacings are these 50 ohm antennas ? I want to build a long yagi single channel 12 (207mhz) tv antenna with 75 ohm coax .please help.
May 19th 2017, 19:42

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
http://www.ifwtech.co.uk/g3sek/diy-yagi/dipoles.htm

No, DL6WU Yagis are old designs that are not optimized for direct 50 ohm feed. They are designed to be fed with folded dipoles, as described on the page above. A folded dipole provides a fixed 1:4 impedance step-up, raising the 12.5 ohm impedance of the Yagi to 50 ohms.

Zack W1VT
ARRL Senior Lab Engineer

May 23rd 2017, 18:43

SIZE358

Joined: Apr 19th 2009, 19:30
Total Topics: 0
Total Posts: 0
UPDATE. I built this yagi using ARRL SPACING NOT DL6WU SPACING. Hooked the 75 ohm coax direct to feedpoint and WOW tv signal went from 0 to 63 just by reconfiguring feedpoint and element length and spacing on same old antenna.

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