The 1:9 balun can connect a balanced or un-balanced feed line to a
balanced or un-balanced antenna, however not un-balanced to un-balanced
and has an impedance step up from
typically 50ohms to 450ohms or 75ohms to 675ohms. The 1:9 Voltage balun is designed
around a
FT140-43 Ferrite Toroid Core and it is recommended
that a chocking balun be included for un-balanced feed line connection.
Similar to the version 1 balun this version has
achieved greater transformation consistency over a greater band width
due to the evenly spaced winding.
See photo1
Construction
The 1:9
voltage balun has 5 turns wound evenly spaced around the FT140-43
Ferrite Toroid Core. The attention to evenly spaced winding significantly
improved the efficiency and bandwidth of this balun compared with the
version 1 balun.
The toroidal
core was wrapped in overlapping layers of PVC electrical tape to protect the enamelled copper wire from insulation puncture from
abrasion with the toroid core and to prevent the windings from
slipping so as to maintain the winding spacing.

Figure 1 Schematic of the 1:9 Voltage balun

Figure
2 Wiring of the 1:9 Voltage
balun.
Note this drawing shows
winding connections and not the number of turns required. See article
for details.
Type
|
Voltage
Balun
|
Ratio
|
1:9
|
Frequency
Range
|
0.5
~ 60MHz
|
Core
Used
|
FT140-43 Ferrite Toroid Core
|
Number
of turns
|
5
x 3 Evenly spaced.
|
Wire
size |
1.25mm
Enamelled copper wire. |
SWR |
Low
1:1.06 (5.1MHz) High
1:1.27 (60.0MHz) |
PEP
Power Handling.
|
Approximately
100W
|

Photo 1 1:9 Voltage balun
assembled.
The evaluation of the efficiency of the balun over
the desired bandwidth (1.0 - 60MHz) 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 antenna analyser. The below
antenna analyser plot views a 450ohm resistive load attached to the
high side of the balun and measured at a nominal
50ohms impedance and should present an approximate 50ohm load to the
analyser and produced about a 1:1 SWR.
The performance of the balun from 0.5MHz to 60MHz is good and shows little reactance, there is however a
gradual rise in reactance above 30MHz along with a gradual rise in the
SWR. Despite this rise in reactance and SWR the balun should will
stilll perform well up into the 50MHz amateur band.

Figure
3 SWR.
The AIM 4170C antenna analyser data
graphed a 450ohm resistive load through the voltage balun from 0.5MHz to 60MHz. Note the 450ohm resistor appears as
50ohms due to the 1:9 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 overt 1:1.2 for the 6m band.
 Figure
4 The AIM 4170C antenna analyser data
graphed a 450ohm resistive load through the voltage balun from 0.5MHz to 60MHz. Note the 450ohm resistor should ideally
appears as 50ohms due to the 1:9 balun ratio.

Figure 5 The AIM 4170C antenna analyser data
graphed a 450ohm resistive load through the voltage balun from 0.5MHz to 60MHz. Note the 450ohm resistor should ideally
appears as 50ohms due to the 1:9 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 1:9 voltage balun using a FT140-43 Ferrite Toroid Core represents a very
efficient balun for a frequency range from 0.5MHz to 60MHz 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).
|