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Measurments on muRata CFJ455K 14

Updated: Dec 29, 2020

Input / Output impedance = 2.000 Ohms

Measuring setup:


Transformer impedance ratio = 2.000 / 50 Ohms = 40

I started with 2 turns / 13 turns but the impedance of the transformer was too low (see my blog "how many turns are needed").

So, next try was with 3 turns / 19 turns. This was very good at first sight.


Measuring results:



SWR rose with decreasing frequency so for 455KHZ it was already nearly 1.7


I decided to take 3 cores to get better low frequency behavior (see my blog "transformers for receiving antennas").



SWR @ 455 KHz is now 1.01


Insertion Loss measurement:

@455KHz only 0.21 dB which is negligible.

The results:


SWR


Insertion Loss

Specification ==> Maesured value

IL < 7dB ==> 4,9 dB

6 dB BW +/- 1.1 - 1.3 KHz ==> - 1 KHz + 1.3 KHz

Max. BW total < 4.5 KHz ==> 2.3 KHz


@ - 1.75 KHz suppression = 72 dB

@ - 1.95 KHz suppression = 65 dB

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