Here I present an inductively coupled trap that I built to be used with my Big Litz set. This coil shares the same diameter and construction as my main set tuning and antenna coils. With this big boy I can tune to the offending signal and trap it very effectively. I have measured and modeled each component of the trap separately, and I have measured the performance of the assembled trap as well. All this permits me to compare the modeled, or expected performance to the actual performance. The goal is to build a high-Q trap with a deep narrow notch in order to trap out strong local signals and dig out nearby DX.
In making Q measurements on any component (Capacitor or coil), one must have one component calibrated and measure the tank Q itself. From the tank Q and calibrated component Q, it is straightforward to mathematically extract the Q of the component under test. I also wish to know the trap Q across the entire MW spectrum as it is not a constant value. In the following discussions then, I will present diagrams with the measured tank Q, calibrated component Q, and extracted component Q versus frequency. I also present the measurements with a model of the expected trap Q versus frequency and the actual measured Q versus frequency. Finally I give the resonance and phase measurements at a frequency of 1100 kHz.
An inductively-coupled wave trap is a fairly simple device consisting of a single tank, One variable capacitor and one coil. For my trap I have wound a basketweave of 5 inches diameter with 46 turns of 660/46 litz wire for low skin and low resistivity. The chart at left shows my measurements and Q calibration for the coil. Green points indicate my calibrated capacitor and the orange points are my measurements on the tank. From those I have ectracted the coil Q across the MW band. Q = 1100 at 1 MHz, just what you expect from big litz.