Quote:
Originally Posted by fmnotes
You need to know receiving frequency first to calculate Nr. of turns.
WHO FREQUENCY YOU BELIEVE THAT THEY IS BEST? 5.7KHZ???
I THANK YOU FOR THE ANSWER, BUT I DID NOT UNDERSTAND WELL WHAT TO ME YOU SAID.
Coil in such design can be from centre to 1/4 of turns (from ground side) tapped
THANKS
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5,7kHz can be ok. There is not guarantee that this is "gold" frequency if you wish to get right those frequency.
Frequency of your ferrite antenna depend on your tank circuit which consist of used ferrite rod, coil and capacitor.
Ferrite rod is as is, mean you take what you have in your lab stock.
Capacitor can be adapted to desired frequency. By the way, I think there is mistake in schematic: C 4,7nF need to go to ORANGE position and C 10nF to GREEN position.
Coil can be calculated to desired frequency. If you follow 5,7kHz then whole coil inductance using c 4,7nF (connected to "orange" position) have to be about 166mH.
Coil can be centre tapped. But you can try coil tapped at 1/4 of turns, count from ground side too.
How to calculate approximative number of coil turns? You need to wind about 10 test turns of wire on your ferrite rod, measure inductance, divide 166mH by measured inductance and multiply result by number of your test turns (10 or so).