The construction and technology of miniature neutron tubes designed at the Institute of Nuclear Techniques are described. The diameter of the tube is 24 mm and the length 140 mm. The tube is used in a bore-hole probe of neutron generator; in addition to its main purpose, i.e. acting as neutron source, the tube also works as a hv rectifier. The output of the tube is 2 × 10 7 n/s for pulsed operation at the accelerating voltage of 100 kV, neutron pulse width 100 μs, repetition rate 400 Hz.