[Lowfer] 17.8 kHz TACAMO

[JD]

>>> No doubt my current antenna is a bit small, but I can only receive 
>>> signals below AMBC when I disconnect the co-ax shield, which allows 
>>> noise from the shack to get into the receiver.

That way it is not working as a transmission line at all, but merely a long 
and not ideally situated extension of the antenna itself.  That effect is 
consistent with what I said about serious impedance mismatch.

(Assuming there's not a short somewhere along the length of the cable or a 
break in the center conductor somewhere close to the antenna end, of 
course... but if there were, it wouldn't work so hot at AM or shortwave 
frequencies either.)

If you had a broadband transformer you could experiment with, or were 
willing to build up a simple buffer circuit, you might be amazed what your 
antenna could do.