As I hinted elsewhere, upheaval due to winter and spring storms here in California caused the long wire here at PVC to be temporarily disabled. Repair work to fences saw some disruption at the spot were the antenna is terminated. IN the process, the 9:1 isolating transformer was misplaced. This had been wound on a randomly selected small toroid, but happened to have a respectable LF response - clear reception of WWV being a fair indicator.Upon reinstallation, a new core was found, and the system reconnected. Things were fine at MF, although with signals so strong (S9+40 at 580 kHz) registering at the receiver, it was difficult to tell. Going lower, it was evident that most of the reception was common mode noise from the feeder, rather than anything from the antenna. WWV absent from the dial. was a big clue.
Back to the drawing board, and the junk box. The replacement transformer winding inductance was measured hastily, and proved to be far too low (I forget the numbers). Searching the junk box turned up some 1/2" x 3/4" ferrite "beads" of unknown provenance. A test winding of 10 turns provided a healthy 800 or so uH. A 9:1 UNUN was wound using 12 T primary and 4 T secondary, and connected up as before: Primary to the antenna drop wire and ground rod. Secondary connected to the coax feed back to the radio bench. No connection between coax and antenna ground.
This setup saw WWV restored, Healthy signals from the Loran C system, and more besides. I had expected HF performance to suffer, but good results were obtained up to and beyond WWVB at 20 MHz. 22 m Showed different reception characteristics to the dipole used most frequently on this band, but a more systematic comparison is needed here. (atmospheric) noise levels are very similar.
If there is interest, I can try and find out more about the cores used. The ones I have came from a long lost surplus place. A few more measurements could suggest the "mix" used.
I might test alternative transformer windings, but for now, PVC has restored LF reception.
73s
Ed