Dear Rich,

If the chokes have fairly low inductance (so that XLchoke < XCant; total
L < several 100uH) or they are part of some sort of tuned trap resonant
at 1097kHz, I guess this arrangement will result in the antenna feed
point having an inductive reactance at 136k, so you will need to add
capacitance to tune this out. How much capacitance will depend on the
choke inductance - you could probably calculate that to a reasonable
approximation by measuring the size and number of turns. Or better
still, measure the actual impedance if you have the necessary test gear.
I guess it would be some nF. It would have to have high RF
voltage/current rating. Connecting the resonating C between ant feed and
ground would probably give quite a high resistance at 136k; connecting
the C between ant feed and TX output a very low resistance. Either way,
you would probably need additional matching to the TX output, either
using a transformer or by tapping the capacitor. The efficiency of this
kind of matching network would depend a lot on the Q of the chokes at
136k, and the other components, and would probably be much lower than if
they were not there - but since the AC feed chokes can obviously take
quite big RF currents and voltages, they might have reasonably high Q,
and since the antenna is so big, you will be able to radiate a good
signal even if efficiency is quite low.

Cheers, Jim Moritz