On Fri, Nov 5, 2021, at 09:50 AM, Dennis Atwood wrote:
Sorry if I'm not understanding, but as long as you carefully count the turns, the inductance will be correct.? You're right, the spacing of the turns really don't change inductance, it's purely the number of times the wire goes through the hole.? (The wire gauge won't change the inductance either.)
Dennis,
You are correct in the points that wire size does not impact inductance and that the number of turns is the critical one.? That is assuming that you are not overlapping the turns.? As Hans has pointed out in tweaking the QCX series of low pass filters, spacing on the toroid DOES impact the inductance of the inductor, though not as much as adding or subtracting a turn.? It is also in the QDX manual to tweak the bandpass filter on the input of the receiver (page 89 of the manual).
Suat,
You can get the normal inductance value from this web page:
You enter in the number of turns and then press calculate to get 8.24 ?H for the full 41 turns.? Press clear and then enter in the other number of turns to get the tap point inductance from the start.
On Fri, Nov 5, 2021, at 07:39 AM, Suat Alper Seyhan wrote:
Now when I do a RF sweep on terminal I see a very wide almost non existing filter on 20m and the maximum attenuation point exactly on the 80m operating frequency. Both bands will be useless I'm afraid. 30-40m sort of ok. Squeezing or widening the spacing on it does not do much of a difference. I have some other wires on the way (could not find 0.33-0.32 but I ordered some? 0.30 and 0.35. Probably I will rewound the L12.
Would it be possible to post screenshots of your sweeps?? Based on the problems being 20 and 80 meters I suspect that the larger number of turns (the first 19) are off.? I would recount that section of L12.? This is just a guess on my part, using the circuit to figure out which taps correlate to which bands, also a guess as I do not have access to the program.
Also, a high-resolution picture of your L12 would help.
73
Evan
AC9TU
