"Ian Jackson" wrote in message
...
- snip -.

Unless I'm losing the plot, the 'innards' of 50 ohm N and BNC connectors
are compatible, and can be mated. This is NOT true for 75 ohm versions.

For N-connectors, there is a noticeable difference in the diameters of the
male pin and the female receptacle (?). The diameter of the 75 ohm is much
less than that of the 50 ohm. If you insert a 50 ohm male into a 75 ohm
female, you will splay the leaves and almost certainly case irreparable
damage. However, if you insert a 75 ohm male into a 50 ohm female, it
won't make contact (unless you first cunningly insert a short piece of
wire into the female).

For BNC connectors, 50 ohm CAN mate with 75 ohm, and vice versa. This is
because the dimensions are essentially identical (although the 75 ohm male
pin is sometimes more tapered). The difference of impedance is achieved
mainly by having much less PTFE dielectric in the 75 ohm version.

As the 50 and 75 ohm BNC male pin is the same diameter as the 50 ohm N
male pin, you must never insert either a 50 or 75 ohm BNC male into a 75
ohm N female. However, you CAN insert a 50 ohm N male into either a 50 or
75 ohm BNC female. However, if you insert a 75 ohm N male into either a 50
or 75 ohm BNC female, it almost certainly won't make contact.
--
Ian


So refreshing to see someone stating it correctly when all around there are
folk who harbour mistaken beliefs that 50 and 75 ohm BNC pins have different
mating diameters. What I find odd is that so many people who claim the
contrary appear to have unshakable belief, almost like a religion,
irrespective of what the manufacturers' engineering drawings actually show.

Chris