I use an ft817 and a 4 element lightweight quad I bought off ebay.
I have had a near two year ordeal with my power company and things are finally pretty good here. My power company is now responsive to the rfi.
Forget about the transformers. Very rarely do they cause the problems. Usually simple loose connections, dead end bells, and slack span insulators. "All" of my 9+ sources were of this nature. My neighborhood is about 40 years old and thus the lines are too.
Good info at ARRL (do google searchs) and do a search for K3RFI, a well known expert in the field of power line rfi.
Keep good records. I have a notebook that is crammed full of all my info.
Lastly go to my website www.qsl.net/af4o
for my info.