[AMRadio] new antenna and matchbox a bust.

[D. Chester]

I think I now get it.  You are using the RG-214 as feedthrough through the 
window.  That wouldn't be a problem if you were at a current loop, which 
makes it a lo-z feedpoint at the end of the open wire line.  But your 
arrangement is a high-z with a lot of  reactance.  Try stripping the shield 
off the coax, and slip the bare centre-conductor through the window, so that 
it simply serves as a feedthrough insulator.

You still need to get away from the 90-ft total of  feeder + antenna  leg. 
That's about the worst possible length to feed unless you have a tuner with 
extremely wide range, probably beyond the capabilities of the matchbox.

I used to pass open wire line through a window by  substituting one of the 
window panes with a sheet of plexiglas.  Then I could drill holes in the 
plastic window pane and pass the wire right through.  Save the glass pane so 
you can put it back in, if sometime in the future you wish to remove the 
antenna from that location.

Don k4kyv