All good advice, (post # 2), Lawrence; I would add just one thing. If the receiver under test is an A.C. / D.C. set, it is very important to connect an isolation capacitor between the sig. gen. signal earth and the chassis of the set: the sig. gen. 'earth' will be (or certainly should be) at real mains earth; the chassis of the radio won't be. Obviously, that only applies if the sig. gen. earth actually needs to be coupled to the radio 'earth': not all forms of signal injection will require that precaution. Note: even if using an isolation transformer to power the set, the above is still a good idea.
Al.
Al.
