Test Results for 50:200 and 75:300 ohm 4:1 Toroid Balun Using FT-140-61
Measurements taken on Autek VA-1 analyzer - with normal inaccuracies - showing swr.
Windings for 50:200 ohm: 12 turns 1.25mm winding wire bifilar wound, all close spaced turns.
Windings for 75:300 ohm: 12 turns 1.25mm winding wire bifilar wound with twine between bifilar pair.
Spacing material: Kinnears 540 TEX colourfil twine; product code K 069048; newsagents, craft suppliers.
| Freq (MHz) |
SWR |
| 50:200 |
75:300 |
| 1.8 |
1.18 |
1.34 |
| 3.55 |
1.12 |
1.17 |
| 5.0 |
1.06 |
1.10 |
| 7.05 |
1.03 |
1.06 |
| 10.1 |
1.04 |
1.02 |
| 14.2 |
1.04 |
1.05 |
| 18.1 |
1.13 |
1.08 |
| 21.2 |
1.13 |
1.07 |
| 28.5 |
1.13 |
1.20 |
24/04/07
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