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ANTENTOP- 01- 2004, # 005  

Something about ATU

 

 

L- Matching Unit

 

Fig. 14 shows L- MU. This one is a simplified version of Pi – MU.  ATU, keeping L- MU often is used for operation with simple tube and transistor transceivers and for matching simple multi- range antennas, which do not contain large reactive component.

Parts for the ATU

 

The data of spools for the MU exhibited on Fig. 2 are shown in Tab. 1, for the MU exhibited on Fig. 3 are shown in Tab. 2.

 

Table 1 Data for MU exhibited on Fig. 2

Frequency band,

MHz

1,9

3,5-3,8

7

10

18

14

21

24

27-30

Diameter of

spool, mm

 

50

 

30

 

25

 

25

 

25

 

25

 

25

 

25

 

25

Length of

winding, mm

 

50

 

30

 

40

 

40

 

40

 

40

 

30

 

30

 

30

Number of

turns

 

100

 

30

 

20

 

15

 

10

 

11,5

 

8,5

 

7,5

 

6,5

Table 2    Data for MU exhibited on  Fig. 3

Frequency

band, MHz

1,9

3,5-3,8

7

10

14

18

21

24

27-30

Diameter of

spool, mm

 

50

 

40

 

25

 

25

 

25

 

25

 

25

 

25

 

25

Length of

winding, mm

 

60

 

40

 

40

 

50

 

40

 

40

 

40

 

40

 

35

Number of

turns, n

 

130

 

35

 

28

 

20

 

15

 

11,5

 

11

 

9,5

 

8,5

Tab. 3  Data for digital inductor shown in  Fig. 9

Inductance, μH

8

4

2

1

0,5

0,25

0,12

Diameter of

spool, mm

 

30

 

20

 

20

 

20

 

25

 

10

 

10

Length of

winding, mm

 

30

 

20

 

25

 

20

 

20

 

10

 

10

Number of

turns, mm

 

20

 

18

 

12

 

8,5

 

5

 

6

 

4

 

It is possible to use for T –MU any variometer, which is possible to get. Variometer has to have maximum inductance not less than 30-μH and minimum close to zero. If the maximum of the inductance of the variometer is less, for expansion of frequency range of the ATU to include in serial with the variometer a fixed inductor. If the minimum inductance of the variometer does not reach zero, it is essentially cut off the upper range of operation of the ATU.

The design data for spools for digital inductor shown on Fig. 9 are shown in Tab. 3. Significant RF-currents flow through parts of MU - capacitors, inductors, and switches.  So all of the parts should be qualitative.

 

73! I.G.

   

http://www.antentop.org/

Page 45

 

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August 7, 2016 20:24

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