The colorful CA-1630 is more than just a drug-store tube tester, rather, it is a precision laboratory-grade equipment to accurately measure the transconductance of a wide variety of vacuum tubes. Its vintage is late 1950s or early 1960s. The tester was recapped and realigned October 2017, and prepared for use. The tester measures the transconductance of vacuum tubes. Transconductance is the characteristic of a tube that measures its ability to amplify a signal.