I often fly with tools and equipment - agree with above although maybe leave the batteries in. I have sometimes been asked to demonstrate portable equipment working - Presumably if it seems to work and its owner seems to know how to operate it, it's more likely to be genuine rather than a suspect device.
Probes and handtools absolutely must not be in hand baggage. I think they have a flat 'no' policy to tools because it avoids dispute over whether a particular tool could or could not be used as a weapon. A few times when I have been in a hurry, something prohibited has got left in my briefcase or laptop bag by mistake, and I've ended up going back out of security and either getting a small bag and checking it in, or a jiffy bag and mailing it to myself.
Once I had some kind of specialised crimp tool worth hundreds that got left in an inner pocket. Baggage check-in had closed so I got a jiffy bag, packed it and then found it wouldn't fit through the thin (bomb-rejecting) slot on the mail box. So I had to unpack, dismantle the tool into piece parts, go get another bag, repack and post. Made it back OK.