Sure is fun with good test equipment........ I deleted the last picture because it may cause confusion.
#1 The first plot is the coupling between the Armature and the coil for a small 10 pin Omron relay.
#2 The second plot is the coupling between the Armature and the coil for a larger 16 pin HFD27 relay. You can see that it is about 7dB worse than the Omron.
#3 (deleted) I tried various RF chokes (1uH to 100uH) which improves the HFD27 relay plots but not at the low end because of the self resonance of the inductor. The Bourns 100uH inductor I was using has a self resonance at about 10MHz. This requires some more study and head scratching.
73 Kees K5BCQ
