My portable doublet looks like shown in the photos, antenna wire is Polys-26 or Radox-125 (0.25mm2).
BTW, Another wow effect for newbies on multiband doublets (double zepps) will be the existence of unsuitable overall wire lengths because the total wire length of the feeder and antenna leg is of relevance for the impedance occurring at the feedpoint.
To be honest I could never measure any signal difference (continental and intercontinental) when operating the doublet with or without an 1:4 Balun connected to the K2 and KX3.
