Andrew said:
According to the service manual for my spectrum analyzer: "when replacing
semi-rigid pipe connections it is imperative that the following torque
settings are used: SMA: 99 - 106 N-cm; SMC: 42 - 49 N-cm"
1. Is it really that imperative?
2. Does anyone know where I can buy suitable torque wrenches in the UK?
Thanks,
Andrew.
I haven't used SMC much so the following applies to SMA.
You could probably hook a spring balance (or just a spring with a known
extension at the required tension) to the other end of the spanner.
If the connectors are too loose, they may fall off or give unreliable
contact after exposure to vibration. If you do them up too tight you can
damage the connectors (I have read that the pins can be compressed too much
amongst other things). If you do them up just tight enough that you think
they won't come loose of their own accord, and no tighter, then you should
be fine. The 7% or so tolerance that they specify in your manual is
probably unnecessary for normal purposes. When using a network analyser,
in my experience I have never been able to see any electrical difference
between finger-tight (i.e. done up with my fingers and no spanner) and
torque-wrench tight. The advantage of using the torque wrench is that I
can then do them up tighter so that I have more confidence that the cables
won't come loose later. If you'll be around to re-tighten the connectors
then finger tight would probably do.
Chris