Full Circle
I went from antenna tuner to resonant dipole fed with coax and now back to non-resonant dipole with antenna tuner again.
Getting the thing tuned up on 75 meters this morning I re-discovered a neat property of non-resonant antennas. They are completely deaf except for the frequency to which they are tuned.
I had this thing tuned to 40 meters. I switched to 75 meters and the receiver went dead. I mean dead as a door nail. Nothing whatsoever. Not even that reassuring crackle of static that you hear when connecting an antenna to the input. It was nearly as though I had pulled the speaker plug. In fact, I did check the speaker plug just to make sure that had not happened.
Once I got the antenna tuned to 75 meters and the receiver peaked for that band, all was well again. Lots of signals and some noise.
So once again I am appreciating the frequency discriminating aspects of an antenna system that requires tuning. All those possibly interfering signals on unused bands that were present with the all band antenna system are gone now. I now have a very selective tuned circuit right at the antenna. In fact, it is the antenna and provides a very nice preselector function.
This got me thinking about resonance and what it means.