The rotations on the Smith chart generally imply of resonance. The resonant frequency is where the trace crosses the real axis. It sounds like you may have moved the SRF inband.
Don¡¯t change your setup, but remeasure the first coil. If you repeat your original result, you can conclude that your test configuration is probably correct and sound. Beyond that, trust the measurements. For collateral confirmation, enter the coil dimensions into one of the online solenoid coil calculators, and compare the predicted inductance values for ballpark agreement with your measurements.
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73
Gary, N3GO
