| 2-El.-6-17m-V. Mk Vl |
2-Element-Portable-Yagi Version Mk Vl,
dismantable, for 6 m-17 m (by DK7ZB)
 |
The beam is a leightweight construction with reduced element diameters. A long test at IS0/DK7ZB in may/june and september/october 2011 showed the excellent performance of the 2-element-Yagi. It has a boom length of only 1,20 m and is fed with impedance chokes. For changing the band the tubing lengths must be corrected and the impedance choke must be mounted. All parts have length of max. 1,45 m an fit in a bag for fishing rods. Picture left: 10 m Picture above: 17 m |
| Attributes of the 2-Element-Yagi on the different Bands |
Band |
Impedance |
Director
distance |
Gain |
F/B |
|
6 m |
28 Ohm |
0,05 and 0,2 lambda |
5,7 dBd |
8 dB |
|
|
10 m |
28 Ohm |
0,1 |
4,5 dBd |
12 dB |
|
|
12 m |
28 Ohm |
0,1 |
4,3 dBd |
15 dB |
|
|
15 m |
12,5 Ohm |
0,085 lambda |
5,1 dBd |
8 dB |
|
|
17 m |
12,5 Ohm |
0,072 lambda |
4,9 dBd |
13 dB |
| The feeding chokes for the different bands |
Band |
Impedance of the choke |
coax (V=0,667) |
Length |
|
6 m |
37,5 Ohm |
2 x
RG59 |
1,00
m |
|
|
10
m |
37,5 Ohm |
2 x
RG59 |
1,76
m |
|
|
12
m |
37,5 Ohm |
2 x
RG59 |
2,00
m |
|
|
15
m |
25 Ohm |
2 x
RG58 |
2,36
m |
|
|
17
m |
25 Ohm |
2 x
RG58 |
2,76
m |
The Tubes for the dismantable Beam
|
Al-Tubes |
Pieces |
Length |
Purpose |
|
20 x 2 mm |
2 |
64 cm |
middle parts radiator |
|
20 x 2 mm |
1 |
130 cm |
middle part director |
|
16 x 1,5 mm |
4 |
145 cm |
intermediate parts radiator and director |
|
11,5 x 1,5 mm |
4 |
125 cm |
intermediate parts radiator and director |
|
8 x 1 mm |
2 |
125 cm |
end parts radiator 15 m und 17 m, Dir. 1 for 6 m |
|
8 x 1 mm |
2 |
110 cm |
end parts director 15 m und 17 m |
|
11,5 x 1,5 mm |
1 |
50 cm |
middle part director 1 1 for 6 m |
|
30x30x2 mm |
1 |
128 cm |
square boom |
 |
The picture shows the middle part of the radiator with
the impedance choke and the boom mounting.
When changing the band an other choke must be mounted. The choke for 12 m can be used on 10 m, too! If you are not sure about the feeding read the "DK7ZB- Match" carefully. |
The aluminium tube lengths for the 17-m-band (band with the longest elements)
|
Lengths
of the tubes for the different bands |
|
||||||
|
20
mm |
16
mm |
11,5
mm |
8
mm |
over
all |
|
||
|
6 m |
Rad. |
65 cm |
87 cm |
- |
- |
152 cm |
|
|
Dir. 1 |
- |
- |
25 cm |
118,2 cm |
125 cm |
|
|
|
Dir.
2 |
65
cm |
72
cm |
- |
- |
137
cm |
|
|
|
10 m CW |
Rad. |
65 cm |
135 cm |
67,5 cm |
- |
267,5 cm |
|
|
Dir. |
65 cm |
135 cm |
50 cm |
- |
250 cm |
|
|
|
10 m SSB |
Rad. |
65 cm |
135 cm |
62,5 cm |
- |
262,5 cm |
|
|
Dir. |
65
cm |
135
cm |
45,5
cm |
- |
245,5
cm |
|
|
|
12
m |
Rad. |
65
cm |
135
cm |
104
cm |
- |
304
cm |
|
|
Dir. |
65
cm |
135
cm |
83,5
cm |
- |
283,5 cm |
|
|
|
15 m CW |
Rad. |
65 cm |
135 cm |
115 cm |
46 cm |
361 cm |
|
|
Dir. |
65
cm |
135
cm |
115
cm |
34,5
cm |
370,5
cm |
|
|
|
15
m SSB |
Rad. |
65
cm |
135
cm |
115
cm |
42
cm |
357
cm |
|
|
Dir. |
65
cm |
135
cm |
115
cm |
30,5
cm |
349,5
cm |
|
|
|
17
m |
Rad. |
65 cm |
135 cm |
115 cm |
111 cm |
426 cm |
|
|
For 50 MHz the Yagi is constructed as a 3-El.-Beam with radiator and 2 directors:
The 3-El.-Beam has a gain of 5,7 dBd and a F/B of 8 dB and a good bandwidth |
