New Q measurements in:
Wanted to measure an Iron Powder Toroid with Q-Curve within nominal
Q-Meter, 400pF to 500pF, maximum resonating capacitor value. Selected
T80-2 80 turns #26
Several evaluations documented.
1. Evaluate S11 Q measurement range and process. As shown VNWA
resolution is insufficient at higher Q values. Low frequency Q, Wire Rs
region, appears to be valid. High frequency region follows bandwidth Q
measurement.
2. Evaluate Rs and Rp Q model. Series wire, square root frequency, Rs Q
is a good match. Using fixed parallel core Rp does not match well. Core
loss must increase as frequency increases.
3. Evaluate Series resistance for two different capacitors. Summary in
table "VNWA Bandwidth Q using 150pF Variable and 120pF C0G." 150pF
variable and 120pF C0G has higher Q than 400pF variable. If capacitor Rs
is constant, with respect to frequency, would expect "Rs Delta" column
to be a constant value.
John KN5L
