Q of chineese iron powder cores

[vk4ffab]

Q = |X| / Rs or  Rp / |X| see article of Jacques Audet, VE2AZX

Yeah I think there is something wrong with my first plot. I will re-calibrate the vna tomorrow morning and make up a new test jig. 1

EDIT: did the calibration and got out a quality hardline patch lead and this is what i got. Q of about 150 at 14mhz. Will redo it in the morning when I am less tired and make a new test jig to eliminate any other error. A value somewhere between 50 and 200 would be typically expected. And this value is within that range.

[paul002]

Just received new cores, but to my supprise they are also fake  . Unbelievable will return it. I did not imagine that german company sell stuff like this. 20 trurns give 2.4 uH instead of 2.0 that already made me suspicious. Now to find a good source of cores.

[chris_leyson]

A long time ago Micrometals published a warning to it's customers saying that Chinese equivalents were not the same. Buyer beware.

[vk4ffab]

Just received new cores from Reichelt, but to my supprise they are also fake  . Unbelievable will return it. I did not imagine that german company sell stuff like this. 20 trurns give 2.4 uH instead of 2.0 that already made me suspicious. Now to find a good source of cores.

Diz from kits and parts in the usa or mark from minikits in australia

[paul002]

Thanks will go there.

Just received new cores from Reichelt, but to my supprise they are also fake  . Unbelievable will return it. I did not imagine that german company sell stuff like this. 20 trurns give 2.4 uH instead of 2.0 that already made me suspicious. Now to find a good source of cores.

Diz from kits and parts in the usa or mark from minikits in australia

[paul002]

It looks like ow mr Reichelt an apology    . Somehow I was not happy with the measurement of the cores I received yesterday. Did some research and found a methode described by W7ZOI in his evaluation of the nanovna. He describes that measuring high Q will not always work on a (nano)vna. So I tried that methode. You create a pass thrue connector with two sma female connectors and connect the core in serie resonance to ground. Measure the S21 gain and calculate the q described in the book Experimental Methodes in RF design. Now the Chinese core still measures a Q of 31 and the new core from Reichelt a Q of 200.
Somehow the methode of connecting the core direct to the S11 port does not work for me.