There are two types of N connectors, one for 50 Ohms and one for 75 Ohms.
The N connector is controlled by MIL-C-39012.
50 Ohm N type connector center pin - 0.0650 ? 0.0005
75 Ohm N type connector center pin - 0.0355 ? 0.0005
Plugging a 50 Ohm male connector into a 75 Ohm female will damage it.
Plugging a 75 Ohm male connector into a 50 Ohm female will provide a crappy
connection.
Best regards, Steven
----- Original Message -----
From: "Tony Duell" <ard at p850ug1.demon.co.uk>
To: <cctalk at classiccmp.org>
Sent: Monday, May 25, 2009 10:57 AM
Subject: Re: Jones plugs, or similar sorts of plugs
 
 N connectors suffer a fatal flaw - use the wrong plug in the wrong
 socket, and you are screwed. Mixing 50 and 75 Ohm Ns will either
 result in a crummy connection or a possibly ruined part. 
 I asusme this is due to a different diameter central pin -- small pin in
 large socket causes a bad connection, large pin in small socket wrecks th
 socket.
 I've heard this claimed of BNCs too, but I've seen measurements made on
 new, good-qulaity BNC plugs (Amphenol, Greenpar, etc) which indicate the
 central pins are the same diameter and there is no possiblilty of damage
 by using the 'wrong' plug. Has anyone got measurements for N connectors?
 -tony