I would like to run some transmissions on MF WSPR but i also like to run
a longer transmission on 2.97 kHz. In the current ULF TX installation
i'm using a parallel 2 nF capacitor anyway. This is just -j167 Ohm on
MF. I could series compensate it with 65 uH (which is just j1.2 Ohm at
2970 Hz :-) ) to ground. The 65 uH could be parallel compensated for MF,
using 280 nF. Then i could add a ferrite transformer to apply the MF RF
across the 65uH/280nF parallel circuit. The large loading coil of 1.3 H
will be a high impedance, hopefully, as long as there is no internal
resonance on MF due to its own winding capacity.
The 2 nF capacitor will have to handle the sum current of ULF and MF.
QRO is not possible on MF i think but it will handle a few watts which
is fine for WSPR. Hmm, worth a try?