I modified my homemade BLT tuner to the Emtech ZM-2 tuner circuit, a single coil Z match.
I modified that circuit slightly to give a low or high impedance input, basically it meant changing the 7 turn link into 4 turn link and adding another link winding of 8 turns wound next to the 4 turn one.
I can now get a 1:1 swr from 80-10 meters on my short inverted V doublett, with the BLT tuner i could get a match from 40-10 but not 1:1 on all bands. The ZM-2 circuit seems much better.