Construction Details

3-El.-10m

4-El-10m

3-El-12m

4-El-12m

3-El.-15m

4-El.-15m

3-El.-17m

4-El.-17m

3-El.-20m

4-El.-20m

5-El-10m

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!

Clubstation TA7KA

in Trabzon

4-El.-28-Ohm-15-m-Beam

3-El.-28-Ohm-20-m-Beam

DO3NDW

DO7NPK and 

 DL1NUX

 mounting the 4-El.-15-m-Beam

 

Link:

Parts available at DL1NUX

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

4-El-10m-28Ohm

3,80m

6,2-6,3-6,4

1,23-1,0-1,46

22-22-20

3-El-12m-12.5Ohm

3,50m

6,1-6,2-6,2

1,18-1,03-1,25

24-25-24

4-El-12m-28Ohm

4,80m

6,5-6,5-6,5

1,04-1,0-1,087

20-20-20

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

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

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.

Impedance matching 28/50 Ohm and balancing with a lambda/4-choke of 2x75-Ohm-coax parallel:

For details see:

DK7ZB-Match

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)

10m

2x1,76 m

2x2,14 m

12m

2x2,00 m

2x2,44 m

15m

2x2,36 m

2x2,86 m

17m

2x2,76 m

2x3,31 m

20m

2x3,53 m

2x4,29 m