In message , Dave
writes
JB wrote:
"Dave" wrote in message
m...
Jim-NN7K wrote:
One thing further- IF you check, you will see that the Physical
Size of a BNC (minus the connector locking outer ring) is the
same size as the N fitting! The "N" male will plug into a "BNC"
female,the BNC without its locking ring will plug into an "N"female!
There are temporary connectors to take advantage of this factor,
for testing (not permanent) connectors ! As info, Jim NN7K

I knew that. I have a home-made pair that I use from time-to-time in
the lab.
If you don't mind GRONKING the BNC fem on your test equipment. Very
naughty!
Once you do "N" you can't go back.


???

I busted the rings off plain old 50 Ohm BNC cables, at the far end. How
does this threaten my Rohde and Schwarz? We never use N cables. We
"permanently" adapt any N fittings to BNC. I made the cables to test a
75 MHz transmitter with reverse thread TNC fittings. How many people
keep reverse thread TNC cables around?

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