So I picked up one of the ARROW II 146/437-10BP portable 2m/70cm beams for some satellite and portable/mobile activity. Three elements on 2m, seven on 70cm.
I decided that I also wanted it on top of a 5m painters pole for easy setup when I am out in the van so I picked up an adaptor from Amazon. It was a bit pricey but it did the job and seems very strong.
I cut up some box section cable trunking I had and mounted to the top of the adaptor with a few screws and washers. I pre-drilled the adaptor plastic.
A small cut out to take the curved section on the adaptor can be seen below. It lets the box section sit flat.
I put together some velcro straps and screwed them into the adaptor with washers. The foam/sponge grip of the antenna sits snugly in the box section and can then be velcroed in place.
A quick test setup on the van on the top of a 5m painters pole. I am looking forward to using it when next out and about.