Apologies for spelling it wrong which may have confused some out there. 
butyl tape, Google it and you will find lots of applications for it besides 
RF connections.  Probably can find it in your local hardware sores 
roofing/flashing section.

I have some that is half inch wide along with some that is two inches wide. 
Depends on what I am cealing but it works really great.  Only caution is to 
use good electrical tape first, then butyl and another wrapping of 
electrical tape and your connectors will stay water proofed no matter the 
weather.

Brian, k5in