1:9 voltage balun using a FT140-43 Ferrite Toroid Core for 0.5MHz to 60MHz. Completed January 2022.

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.

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).

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