...maybe.
Since last I posted, I've experimented with a variety of possibilities; none of which worked...8^(
But, I reverted back to a message where I mentioned building a filter with half of the circuit on each side of a common copper substrate that didn't have the anomaly.
That construction gave me the idea that maybe there was a ground loop; I'd read about that sort of thing but not for HF. Anyway, I reworked one of the LPF PCBs to put all the RF ground connections on one common plane. Via's were added to connect the planes physically otherwise. The attachment shows an ExpressPCB model.
This corrected the effects for 20m, don't know about 30 yet.
--
Chuck, W5USJ
Chuck Carpenter
