9:1 transformer for K9AY antenna.
- xtgaby
- Sep 17, 2020
- 1 min read
Updated: Mar 8, 2021
Picture Schematics


primary 2 turns secondary 6 turns
Used material: 3 cores of 73 material Fair-Rite 2873000202

Input = 2 turns / Output = 6 turns
2 square = 4 / 6 square = 36
36 / 4 = 9
When Input impedance = 50 Ohms,
Output impedance wil be 9 x 50 Ohm = 450 Ohms





At 21.3 MHz impedance is 46 ohms + j10 ohms

Compensation is 34 pF @ 21.3 MHz



S21 Insertion loss for 2 devices:
The K9AY antenna is used at 160 meters and 80 meters.
The setup:


Insertion loss at 160 meters =
0.33 dB / 2 = 0.17 dB
This means a loss of 4 %
Insertion loss at 80 meters =
0.35 dB / 2 = 0.18 dB
This means a loss of 4 %
S21 insertion loss for 2 devices:

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