an amplifier in the form of an integrated circuit chip 51 is mounted on the epoxy 13 a as shown the input terminal 52 a of the amplifier is connected to the appropriate probe wire 52 c via conductive ink strip 52 b the probe wire 52 c is advantageously of the type indicated in fig3 c because the short metallic probe has less capacitance than the longer wires thus minimizing the capacitance loading of the amplifier input similarly the power terminal 53 a is connected via strip 53 b to a probe wire 53 c that carries power the ground or common terminal 54 a is connected via conducting line 54 b to the probe wires carrying ground 54 c the output of the amplifier 55 a is connected via a conductive path 55 b to the central conductor 55 c of a coaxial line the shield 35 of the coaxial line is connected via conductive path 55 f to the ground line 54 b probe wire 55 c may extend toward the tip as shown in fig3 b to make contact with the circuit under test or it may be cut short as indicated in fig5 to serve as an output to the test apparatus as.