For
use with a quick and easy multi-band antenna deployment
for portable and camping operations a simple long wire antenna with an
earth plus counterpoise arrangement with a 9:1 voltage
unun is popular.
Requiring
a unun to feed a long wire antenna mostly with a tuner a 9:1 voltage
unun
design using a FT140-43
ferrite toroid core
was selected.
The 1:9 unun is connect to an un-balanced feed line and to an un-balanced
antenna with an impedance step up from typically 50ohms to 450ohms,
the 1:9 Voltage unun is design using
a FT140-43 Ferrite Toroid Core. It is recommended
that a chocking balun be included for un-balanced feed line connection.
Similar to the version 2 unun the new
version has achieved much improved transformation efficiency over a greater
band-width. The improved transformation efficiency over a greater
band-width is primarily due the the evenly spaced
windings around the core.
Figure
1 Typical
9:1 voltage
unun and long wire antenna configuration.
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 unun.
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.
The
length of enamelled copper wire per winding for the FT140-43
ferrite toroid core
is determined by length per winding plus tails = 350mm
Figure
2 Schematic of the 9:1 voltage
unun.
Typically unbalanced = 50/75 ohms too unbalanced = 450/675 ohms.
Figure
3 Wiring of the 9:1 voltage
unun.
Type
|
UnUn
Voltage
|
Ratio
|
1:9
|
Frequency
Range
|
1.0
~ 60MHz
|
Core
Used
|
FT140-43 Ferrite Toroid Core
|
Number
of turns
|
5
x 3 Evenly spaced.
|
SWR |
Low
1:1.06 (5.1MHz) High
1:1.7 (60.0MHz) |
PEP
Power Handling.
|
Approximately
100W
|
Photo
1 Completed core
winding assembly. note fibre glass
tube sections to hold winding groups together.
Figure
3 SWR.
The AIM 4170C antenna analyser graph viewing a 450ohm resistive load through the voltage balun from 0.1MHz to 60MHz. Note the 450ohm resistor appears as
50ohms due to the 1:9 unun 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 1:1.65 for the 6m band.
Figure
4 The AIM 4170C antenna analyser graph viewing a 450ohm resistive load through the voltage balun from 0.1MHz 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 graph viewing a 450ohm resistive load through the voltage balun from 0.1MHz 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 unun 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).
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