Self-Normalling.
A self-normalling video jack internally routes a signal from one
video device to another. Typically, BNC connectors are used with
the rear source (input, Row 1), and rear destination (output,
Row 2). On the front are standard video patch ports. The internal
normal path runs from the rear source to the rear destination.
The signal can be rerouted by inserting a patch cord into either
front port. Removal of the patch cord returns the signal to the
normal path (i.e., “self-normalled”). These video jacks
are available so that, in a patched mode, the unused signal is
either terminated to a characteristic impedance of 75 ohm, or
unterminated (open circuit).
Termination.
Due to the broadband high-frequency signals used in serial digital
circuits, serious consideration must be given to the proper termination
of all unused signals (although there are some monitoring and
special test functions which do not require termination). Proper
termination of the high-frequency video signal cancels cable reactive
components, improves return loss, minimizes stubbing and antenna
effects, and also helps in meeting RFI/EMI criteria. All of the
terminated video jacks we supply terminate with a 75 ohm characteristic
impedance, and can be used in analog and serial digital circuits.
Single Unterminated.
These jacks route signals straight through, with no normallin
g and no termination.
Single Terminated.
When patched, these jacks route signals straight through. When
unpatched, the rear port’s BNC connection is terminated to
a 75 ohm load.
Dual Self-Normalled
Unterminated.
When patched, these jacks route signals straight through with
no termination of unused signals. When unpatched, the rear source
port is normalled to the rear destination port.
Dual Self-Normalled
Terminated.*
When patched, these jacks route signals straight through, and
any unused signal is terminated to a 75 ohm load. When unpatched,
the rear source port is normalled to the rear destination port.
* = Most common.
