Voltcraft lt 100 lamp tester voltcraft lt 100 p the voltcraft lt 100 is a lamp tester that serves as a diagnosis and error search device on gas filled lighted systems p p the gas filled light is ionised via a high frequency voltage via a telescopic antenna on the test device and should light up during the test an additional test checks the heating coil of the fluorescent tubes an optical and acoustic continuity test should be carried out on both plug contacts of the t series lamps the