The TWINAMP could not be triggered by internal pulse correctly but only by external signal normally yesterday. By my early experience, the problem was caused by the thyratron heater and reservoir voltages. We measured the heater voltage(V_H) from the power supply output, which is about 10.2 VAC. When I decreased this voltage down to 9.4V (the minimum adjustment), the TWINAMP ran well. We also measured the voltages from thyratron side.
Power Supply Output
On May 1st, I set the Heater and Reservoir voltages: V_H=11.35V, V_R=8.35V. On Oct. 18, 2005, we set the voltages: V_H=7.05V, V_R=7.49V.