The new KY6R Inverted L matching unit at the base of the antenna. It is the Palstar AT5K High Pass “Tee” circuit, and being at the base – while the extra capacitor might introduce some loss, having the unit at the base of the antenna most likely makes up for that.
Larry Benko, W0QE, in his FB antenna coupler slide deck:
On page 39 tells the story, and I think answers my question that I posed yesterday. I think at high power, the stresses on my previous two component circuit were just too much. I tested on RBN, and the antenna was radiating and seemed to do well, but if the antenna coupler can’t handle a 160M pileup – you are forced to address this immediately.
Having the three components seems to alleviate the overloading of the components at high power. I will say it has to do with range and stresses imposed on the components – where either the voltage or current was too much for the single L and single C. I saw no signs of arcing – but its hard to examine the capacitor in the weatherproof enclosure, so I will guess that this circuit caused too much stress on the capacitor and the current choke took the brunt of that:
If you have a more technical or better answer – please let me know.