Bifilar Wound Toroids Session 2 Ferrite Transformers for Matching Amplifiers Ferrite Cores for Transmission Lines/Baluns, EMI Powdered Iron High Q inductors: Increased Inductance FT50-43 4:1 Transformer Ferrite

Operating Principles Right Hand Rule For a Solenoid Reversing Current Direction Reverses the Flux B [tesla] B I [Amps] L1 [H] I [Amps]

Operating Principles Right Hand Rule For a Solenoid A simple Experiment with a compass Demonstrated in Lab

Ideal Transformers N1=N2 Identical Windings Lenz and Faraday B1 Lossless 1 mA B1+B2 =0 1 mA B2

Series Connection of Inductors Bifilar Winding: Additive L1=L2 Leq= L1+L2+2M Leq = 4L1 if M = L1 Wind one Inductor: 10 Turns Bifilar Lead Length = 1.5 inches Don’t solder windings yet Measure Single Turn Inductor LC mtr Solder Connections Measure Bifilar Inductor LC mtr Measure input impedance with AIM Compare Single turn and Bifilar Inductance Lbifilar #26 Gauge Yellow Core

Winding Bifilar Inductors Additive Layout wires per top left drawing. Check continuity Connect per top right: Solder “a dot” to b

Series Connection of Inductors Bifilar Winding: Subtractive L1=L2 Leq= L1+L2 - 2M Leq = 0 if M = L1

4:1 Ferrite Transformer Bifilar Wound Zin = 50 Ohms Zload = 200 Ohms b a 2 mA b a Subtractive Currents No flux in Toroid 1mA 1mA 1 mA Make one transformer: 10 Turns FT50-43 material Use #26 Gauge wire and supplied BNC connector Measure input impedance with AIM Impedance meter

4:1 Ferrite Transformer Bifilar Wound Zin = 50 Ohms Zload = 200 Ohms a b b a b is ground.. Bend end up to label a dot is connected to 200 Ohm resistor Connect b dot to a : insert into center pin of connector