1990 Pickup starter/electrical problem

Hello there, I have a electrical diagnosing question. My 1990 nissan pick-up (4 cyl, 2wd, manual trans, KA24E engine, odometer unknown) has been having intermittent slow/weak starts for a week or so and then finally refused to start at all. The battery is fine so I figured the starter was to blame. After removing the starter I applied 12 volts directly to the terminals of the starter to check it and it didn't engage or turn or make any sound. I then checked the two leads with a volt meter and saw there was 12 volts across them even when the key was off. When I turned the key to the start position the voltage dropped to zero!Does this sound normal? I was wondering if I should look for a relay or check the ignition switch before I install a new starter. Hope I have given enough information for a reply! Thanks