[old_tv_nut]

Originally Posted by Chris K

Wow...thank you so much. Resonance...harmonics etc...these concepts have always been the most challenging things for me. I can understand a vibration stimulating something else at rest to vibrate but at the same frequency. I don't entirely understand the production of other frequencies from the primary one.

So by coupling here you mean frequency or vibrational coupling...one coil and slug stimulated electrically transferring this frequency based energy to an adjacent coil? These traps are tuned to eliminate specific frequencies from the signal circuit resulting in a broader bandwidth. At least that's my understanding from an earlier part of this thread. How does this primary/secondary tuned pair do that? I have an idea as to how but I'm not very eager to put it out there!

The coils between IF stages are coupling the output of one stage to the input of the next. But coupled coils can also be used in a trap circuit where one of the coils connects to a circuit that absorbs energy at the trap frequency instead of passing it to a next stage. And sometimes, the coupled coil is both a sound takeoff that sends the sound signal to the audio IF and and also a sound trap in the video path because it sends the sound signal out of the video path and to the sound IF.

Another thing, we are discussing basically linear filter circuits here, which means they (ideally) do not generate harmonics of the incoming signal, but respond with different amplitude to the different frquencies that are present in the incoming signal. This difference in amplitude at different frequencies is seen as the shape of the IF alignment sweep curve.