I decided after the tower was installed that the doublet was getting in the way of using the tower properly. I looked around for an antenna that would work on 80m and 40m I didn't want to buy a commercial vertical. I searched the net and apart from a few loaded and trapped dipoles there was this little antenna from G7FEK. I looked at it carefully, found that it would easily fit into my site and would only cost me time to build as I had enough things in my junk box to do the entire build.
As the picture shows, it is very simple in its layout and can be knocked up pretty easily using any bits that you have to hand. I built mine from some spare flexweave wire, the feeder from my doublet, a couple of bits of pvc wire from an old dipole, a bit of pink acrylic and an so-239.
The only things I did different to the diagram was adding 4 radials instead of the one shown in the diagram. Rather than give lots of blurb here, I'll point you in the direction of the actual designer and the full info... so if you want the full info then follow this link.