There is a thread somewhere about the use of coils in the 60m/40m link so that a linked 20/40/60 dipole is near resonance for 80m also. I have used mine several times this month with more success than 60m on several occasions. Allan, GW4VPX/P, and I made pairs of coils and they turned out to be very different but both sets worked.
Might be out with them on SW-012 Saturday pm.
I will try to find and add a link to that thread:-