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Clubstation TA7KA in Trabzon 4-El.-28-Ohm-15-m-Beam 3-El.-28-Ohm-20-m-Beam |
3- ,4- and 5-Element-Yagis for the 10 m, 12 m, 15 m, 17 m and 20 m-Band
Click: New 7-El.-10-m-Monster-Yagi with 16,62-m-Boom!
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Clubstation TA7KA in Trabzon 4-El.-28-Ohm-15-m-Beam 3-El.-28-Ohm-20-m-Beam |
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DO3NDW, DO7NPK and DL1NUX mounting the 4-El.-15-m-Beam
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Very important: Do not change the tapering of the elements! Other diameters and lengths of the element parts will cause severe problems and other data.
Short data of the Yagis. Gain, SWR an F/R are given for the beginning, the middle part and the end of each band:
|
Version |
Boom |
Gain in
dBd |
SWR |
F/R in
dB |
|
3-El-10m-28Ohm |
3,00m |
5,4-5,5-5,7 |
1,47-1,0-1,59 |
23-26-19 |
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4-El-10m-28Ohm |
3,80m |
6,2-6,3-6,4 |
1,23-1,0-1,46 |
22-22-20 |
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3-El-12m-12.5Ohm |
3,50m |
6,1-6,2-6,2 |
1,18-1,03-1,25 |
24-25-24 |
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4-El-12m-28Ohm |
4,80m |
6,5-6,5-6,5 |
1,04-1,0-1,087 |
20-20-20 |
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3-El-15m-28Ohm |
4,00m |
5,4-5,5-5,7 |
1,31-1,04-1,54 |
28-28-22 |
4-El-15m-28Ohm |
5,00m |
6,3-6,4-6,4 |
1,1-1,0-1,2 |
23-20-19 |
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3-El-17m-28Ohm |
5,00m |
5,6-5,7-5,7 |
1,1-1,0-1,1 |
26-27-27 |
| 3-El-20m-28Ohm | 5,40m | 5,1-5,3-5,5 | 1,48-1,01-1,57 | 23-25-18 |
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4-El-20m-28Ohm |
7,70m |
6,3-6,3-6,4 |
1,1-1,0-1,3 |
19-24-22 |
Use the DK7ZB-match with 2x75-Ohm-coax for the 28-Ohm-Yagis and 2x50-Ohm-coax for the 12,5-Ohm-Yagis. The two cables must be fixed close together with tape, then form a coil for building a choke. One end is connected to the middle part of the radiator, the other to a grounded coax-socket. At this point you have an impedance of 50 Ohm and there the feeding cable will be connected.
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Impedance matching 28/50 Ohm and balancing with a lambda/4-choke of 2x75-Ohm-coax parallel: For details see: Length is lambda/4xV (V=Velocity of propagation)
A RG59-choke with good MIL-quality will handle 750 Wtts RF |
Lengths of the
parallel lambda/4-cables for the impedance transformation:
|
Band |
Full-PE, V=0,667 (RG59) |
Foam-PE, V=0,81 (CATV) |
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10m |
2x1,76 m |
2x2,14 m |
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12m |
2x2,00 m |
2x2,44 m |
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15m |
2x2,36 m |
2x2,86 m |
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17m |
2x2,76 m |
2x3,31 m |
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20m |
2x3,53 m |
2x4,29 m |
