> We just
> weren't ready to use the time and materials to add an inch to
> a set of cables and then make another set of short ones.
"Connector savers" can be incrementally added to a cable when experimenting
to find the optimum length. Connector savers are male-to-famale adapters of
the same connector type. They are frequently installed on test equipment to
save wear and tear on the built-in connector, hence their nickname. They
are about the shortest length you can add from a mechanical standpoint to
cables that use type N connectors. A line stretcher is the best way to do
it, but connector savers are quick and dirty, and their incremental
electrical length is small enough to make them effective for this purpose at
the frequencies we normally deal with below 1 GHz.
High-quality elbow adapters can be used in a pinch instead, but there are
some caveats with respect to the impedence bump they can create (see the
blurb I put together earlier today that touches on this subject). They are
also electrically longer than connector savers, typically making them useful
only below about 500 MHz in many cases.
If you do this kind of work on a regular basis like we do, you end up with a
few dozen test cables of varying lengths (nominally 1/2" incremental
difference in length) to use when building a system. Once the optimum cable
lengths are found, new cables are made for the final installation.
BTW, when making up cables based on manufacturers' recommend cable lengths,
make sure you know whether the cable length they specify is the "cut length"
or whether it's tip-to-tip. Some manufacturers, like TX-RX, specify their
cable lengths based on the cut length before the connectors are installed,
so the overall tip-to-tip length ends up being about 1.25" longer when type
N crimp connectors are installed.
--- Jeff
