I want to make a simple single layer air cored coil:-
Inductance: 3.9uH. Former diameter: 16mm. Wire: 0.6mm enamelled copper.
Coil calculators on the web all give roughly the same information:-
18 turns should give about 3.7uH.
So I wound 18 turns on a 16mm hollow paxolin former.
I then tried to measure the inductance using a vintage Marconi TF2700 bridge. The lowest inductance range on the bridge is 10uH. I measured 1.35uH.
The bridge is quite old, so I to validate the measurement I tried measuring a commercial 4.7uH inductor. It measured 4.15uH which seems reasonable.
I'm baffled as to why the measured inductance of my coil is so far out.
Inductance: 3.9uH. Former diameter: 16mm. Wire: 0.6mm enamelled copper.
Coil calculators on the web all give roughly the same information:-
18 turns should give about 3.7uH.
So I wound 18 turns on a 16mm hollow paxolin former.
I then tried to measure the inductance using a vintage Marconi TF2700 bridge. The lowest inductance range on the bridge is 10uH. I measured 1.35uH.
The bridge is quite old, so I to validate the measurement I tried measuring a commercial 4.7uH inductor. It measured 4.15uH which seems reasonable.
I'm baffled as to why the measured inductance of my coil is so far out.