Requiring a choking balun to isolate the potential common mode RF on the coax
cable for a new 6m band Ringo antenna.

Figure 1 Schematic of the 1:1 choking balun
Type |
Choking Balun |
Ratio |
1:1 |
Frequency Range |
14 ~ 54MHz |
Choking Impedance |
2k Ohms minimum. Ref:
Figure 3 |
Core Used |
FT140-43
Ferrite Toroid Core |
Number of turns |
8 (4 + 4). Ref:
Figure 2 |
SWR |
1:1 Ref: Figure 4 |

Figure
2 Winding details of the 1:1 choking balun
Construction
The
construction was simply to wind 8 turns of RG174 coax onto a FT140-43
Ferrite Toroid Core. The result of 8 turns
achieved an average of 40uH lumped value inductive reactance to common mode RF
currents from approximately 10MHz to 70MHz.
Parts
list.
- FT140-43
Ferrite Toroid Core
- About
0.3mtr of RG174 coax.
- 2 x N type chassis
mount connector
- Sealed
Polycarbonate Enclosures 82 x 80 x 55mm

Photo
1 Low
band choking balun
assembled.

Photo
2 Rear view of the Low
band choking balun
assembled showing the hose clamp mast attachments.
Testing
The AIM 4170C antenna analyser recorded in Figure 2 show the
Impedance as measured in the coax
shield presents an acceptable 2000 Ohms or greater from 14MHz to
about 54MHz.

Figure
3 The evaluation of the choking impedance of the balun over a bandwidth
from 10MHz- 60MHz.

Figure
4 The evaluation of the balun with a 50 ohm load over a bandwidth
from 10MHz- 70MHz. The balun shows a very low SWR from the ideal
1:1 and despite the visual appearance in the graph this result is
almost perfect and flat.
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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