About 6 months ago I thought I'd try one of these - 2m coaxial collinear vertical. I used 75 Ohm coax seeing I had tons of it. I adjusted the half wave and quarter wave sections for Velocity Factor and started cutting and assembling. I only had room in the crappie pole for the 1/4^ stinger, 1/4^ bottom section, and either 4 or 6 1/2^ sections. Then I abandoned the project because I wasn't sure where to go with it next. I pretty much forgot about it until my ham neighbor asked me when I was going to tackle a collinear. I showed him what I'd started. He told me to put the analyzer on it. Well, it ranged 1.1 to 1.5:1 SWR across! Boy was I surprised. I need to add a set of GP radials and I think I'll be happy ('til the next time). Got a signal check to a reliable station 15 miles south of me. Signal improved on his IC 746 from 5 to 10+ over my 2m j-pole.