Two elements 80M SUPER yagi
- Details
- Category: 80 M
 These two element yagis for 80M is “shorty eighty’, very well optimized and have specifications almost the same as full size yagi. Forward gain is just slightly lower then full size – about 0.2dB. |
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| On 50m high tower | Erecting | Mechanical improvement |
Coils are mounted on the end of the first tube section, about 5m from boom. Actually, I bought 3 elements M2 yagi many years ago, and I had it on tower just few months. Even mechanically that antenna was modified and was more robust that the original one, first strong wind blows up half of two elements easy. My new 80M yagi has to be best compromise in electrical design and reliable mechanical design.
 Analyzing differences between 3 elements on 18M boom, and optimized two elements yagi (driven and reflector) I found absolutely the most rational to put up two elements yagi, described in text below, instead of three elements on 18m boom. Differences are absolutely unimportant and do not deserve investment of time and material. 2L80 is lighter, mechanically very robust and, as it was presented on air in contests, very effective. |
BOOM
Boom used is 18M Al tube, diameter 110mm and 120mm from original M2 antenna. I used 12m as distance between driven element and reflector, and the rest of 2x3m on each side used for mechanical support for elements.
ELEMENTS
Elements are about 30m long. I used M2 Al tubes from original 3L yagi. Mechanically, I redesign elements totally. At the end of firs element tube, on about 5m from boom I mounted two Al tubes with 40mm diameter, in cross, for supporting iron wires, which span the elements. Iron wire in broken with plastic insulator on each 2m, approximately.
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| Single element tuning | Cross | Assembling |
COILS
Coils are 8uH, with Q factor of 450 and are made with 8mm copper tubes. As you can see on photo, ends of coils are mechanically connected with element very carefully, to have very low transient resistance, because on location I have a lot of problems with lightning.
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| Coil to element contact | Coil covered with plastic tube | Coil body |
IMPEDANCE TRANSFORMER
It is 50 ohms to 22 ohms transformer, and at the same time it is CMC choke, too.
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Impedance transformer
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Schematic of transformer
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CW COILS
CW coils are 8uH, made with 8mm copper tubes. I used two16A DC relays (FINDER) in parallel for switching CW/SSB. They are capable to switch up to 3kW.
EZNEC DIAGRAMS
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| Model | EL diagram | SWR on SSB |
EZ file with uniform tubes you can download here
EZ file with original tubes you can download here.