|
Requiring
a balun to feed a balanced antenna from an un-balanced line with a
impedance step up from 50ohms to 300ohms, a 1:6 Voltage
balun design using a FT140-43 Ferrite Toroid Core
was selected.
Construction
The
1:6 voltage balun has 6
x 2 and 4 X 2 turns 0.5mm2 hook-up
wire wound evenly
spaced around the FT140-43 Ferrite Toroid Core. See
Figure
2 and Photo 1 for details.
Figure 1 Schematic of the 1:6 Voltage balun
Figure
2 Wiring of the 1:6 Voltage balun.
|
Type
|
Voltage
Balun
|
|
Ratio
|
1:6
|
|
Frequency
Range
|
0.5
~ 30MHz
|
|
Core
Used
|
FT140-43 Ferrite Toroid Core
|
|
Number
of turns
|
6
x 2 and 4 X 2
|
| SWR |
Low
1:1.2 (2.5MHz) High
1:1.7 (30.0MHz) |
|
PEP
Power Handling.
|
Approximately
100W
|
Photo 1 1:6 Voltage balun
assembled.
The
evaluation of the efficiency of the balun over the desired bandwidth
(1.0 - 30MHz) was carried out by testing the impedance that could be
seen from unbalanced
side to a resistive load applied to the balanced side using an
AIM 4170C antenna
analyser. The below antenna analyser graph shows a 300ohm resistive
load attached to the balanced side of the balun and measured at a
nominal impedance of 50ohms that should presented an approximate
50ohm load to the analyser and produced about a 1:1 SWR
The
performance of the balun from 0.5MHz to 30MHz is good and shows
little reactance, however there is a gradual rise in reactance above
10MHz along with a gradual rise in the SWR. Despite this rise in
reactance and SWR the balun should still perform well.
Figure
3 SWR.
AIM 4170C antenna analyser data
graph viewing a 300ohm resistive load through the voltage balun from 0.1MHz to 30MHz. Note the 300ohm resistor appears as
50ohms due to the 1:6 balun ratio resulting in an ideal SWR of 1:1. The
SWR is shown to be consistently low for all Amateur radio bands with a
high of just 1:1.7 for the 10m band.
Figure
4 Impedance The AIM 4170C antenna analyser data
graph viewing a 300ohm resistive load through the voltage balun from 0.1MHz to 30MHz. Note the 300ohm resistor should ideally
appears as 50ohms due to the 1:6 balun ratio
Figure 5
Impedance (R & X). AIM 4170C antenna analyser data
graph viewing a 300ohm resistive load through the voltage balun from 0.1MHz to 30MHz. Note the 450ohm resistor should ideally
appears as 50ohms due to the 1:6 balun ratio. The impedance
should ideally be R (Resistance) at 50 ohms and X (Reactance) near zero
ohms. The
Purple line shows the resistance component in ohms of the Impedance
and the Orange line shows the reactive component in ohms of the Impedance,
the + values for the reactance represent Inductive reactance and the negative values
represent the Capacitive reactance.
Conclusion
The Version 2 1:6 voltage balun using a FT140-43 Ferrite Toroid Core represents a very
efficient balun for a frequency range from 0.5MHz to 30MHz at a power
level of 100W PEP.
Also
see other baluns and ununs:
BALUN
1:1 CHOKE & 1:4 BALUN HF
ladder feed-line to coaxial cable combination choke and 1:4 balun.
(0.1MHz - 30MHz).
BALUN
1:1 CHOKING Choking balun
for lower HF and MF bands. (200kHz - 10MHz).
CHOKING
1:1 BALUN - HF BANDS Reisert
choking balun.
(1.0MHz - 30MHz). FT240-43 Ferrite Toroid Core.
CHOKING
1:1 BALUN - HF BANDS Reisert
choking balun
(1.5MHz - 30MHz). FT140-43 Ferrite Toroid Core.
CHOKING
1:1 BALUN - LOW VHF BAND Choking balun.
(10MHz - 60MHz). FT140-43 Ferrite Toroid Core.
BALUN
1:1 CURRENT 1:1
Guanella
Current
balun
using a L15 ferrite core (1.8 - 30MHz).
BALUN
1:4 CURRENT 1:4
Guanella
Current
balun
using a L15 ferrite core (1.8 - 30MHz).
BALUN
1:4 SINGLE CORE CURRENT 1:4 Guanella
Current Balun, single FT240-43
ferrite toroid cores.
(0.3MHz - 30MHz).
BALUN
1:1 VOLTAGE 1:1 Ruthroff
voltage balun using a T-200-2
powdered iron toroid core (1.8 -
30MHz).
BALUN
4:1 VOLTAGE 4:1 Ruthroff
voltage balun using a T-200-2
powdered iron toroid core (1.8 -
30MHz).
BALUN
6:1 VOLTAGE - VERSION 1 6:1
Voltage balun using a L15
ferrite toroid core (1.8 - 30MHz).
BALUN
6:1 VOLTAGE - VERSION 2 6:1
Voltage balun using a FT140-43
Ferrite Toroid Core (1.8 - 30MHz)
BALUN
9:1 VOLTAGE - VERSION 1 9:1
Voltage balun using a L15
ferrite toroid core (1.8 - 30MHz).
BALUN
9:1 VOLTAGE - VERSION 2 9:1
Voltage balun using a FT140-43
Ferrite Toroid Core (0.5 - 60MHz).
UNUN
9:1 VOLTAGE 9:1 voltage unun
using a
T-200-2 powdered iron toroid
core
(1.8 -
30MHz).
UNUN
9:1 VOLTAGE VERSION 2 9:1 voltage unun
using a L15 ferrite core (1.8 -
30MHz).
UNUN
9:1 VOLTAGE VERSION 3 9:1 voltage unun
using a FT140-43 ferrite core (0.5 -
60MHz).
|
