113. Vacuum Tube X-Ray Source
Modulator
Low Voltage pentodes such as the 1S4 are useful for simulating x-ray
tube loads that use low voltage filaments. The tubes can be matched and
operated in parallel to drive VMI opto-couplers similar to the ones
discussed in the previous picture. The feedback voltage to the tube grid
modulates the load current in the same way that the control voltage
controls the x-ray tube current. An interesting fact from this test
setup is that the 1S4 tubes were new in the box with dates from 1949 to
1952. They all operated to specification when tested for use in the
simulator. |