Pressurizing the cable is not just a recommendation, It's almost a must-do for use in an uncontrolled environment. It's the only thing that can prevent condensation inside the cable. You also need to pay very careful attention to minimum bend radius to keep the center conductor centered. IMHO you'd be much better off with LDF7-50. No pressurization, less likely center conductor movement, and the loss at 100 MHz is almost identical.
It's recommended to flush and pressurize air dielectric cable with a suitable dry gas to keep moisture out. Are you planning on doing that?
Mike & Don,
We have the Andrew compressor / dryer for the cable, including the alarm switches and nitrogen regulator if it turns out a backup system is needed.
I see the point re the foam dielectric cable, however the air dielectric Heliax was essentially free. I'm hoping to find an Elmer who can show me how to attach the connectors (or at a miniumum can point me in the right direction via e-mail)