[TowerTalk] N-Connector to Super 8 Low Loss Cable?

[Eric - VE3GSI]

Are there any tricks any of you fellows can suggest for putting the pin of
an N-Connector on centre conductors of Super 8 Cable?
 
This is the first time I have tried this combination and found the centre
conductors of the cable too large for the pin. I am making up a jumper cable
for the top of my tower to go from the beam to the hard-line.
 
I have used these same connectors on RG-213 with no problem, so perhaps
there is a different connector model I should purchase. Just not sure!
 
Tnx,
Eric - VE3GSI