How you wind a coil makes a BIG difference.
Ever wonder why your projects don’t work like the authors?
Im winding 42 turns onto a 1 Megohm 1/4W resistor to make a loading coil to make a 5’ whip antenna on a cubesat tune to 28 MHz.
I was getting nowhere trying to add and subtract turns. With a bandwidth of only 200 kHz it was inconsistent getting to 28.120 center freq.
Then I simply took the same length of wire and tried 3 methods all with the same number of turns.
1, down-and-back-and forward for 3 layers = 24.5 MHz
2, left-to-right but scrambled 3 layers along the way = 30.0 MHz
3, just a little squeezing of turns that had loosend = 28.8 MHz
Wow, just changing the winding method moves the 0.2 MHz bandwidth as far as 30-to-1!
The difference of course is the stray capacitance between the end turns.
So winding method is important!
Just thought I’d share the results…
Bob, WB4APR