3-7 PULSE TERMINATING THYRATRONVlb
The pulse from tube V109B triggers the pulse terminating thyratron Vlb.
When fired, this thyratron in conjunction with the discharge diode V8
presents a very low impedance to the pulse from the pulse forming thy-
ratron V6 and causes a rapid fall of the pulse to form the trailing edge.
Additional direct current voltage is supplied to Vlb by means of R28 and
allows the pulse terminating thyratron to fire when the pulse length is
set to a very low value. Tube V8 in conjunction with R10 and C24 allows
the thyratron V16 to be extinguished at the end of the pulse cycle.
3-8 CLIPPER CIRCUITS
The pulse from the thyratron is sent through a series of three diode clip-
pers and then to the output amplifier tube V 11. Tube V7 is the first diode
clipper. Tube V9 is the second and third diode clipper.
3-9 OUTPUT AMPLIFIER
The output amplifier tube V11 feeds the polarity switch where either a
plus or minus pulse may be selected and applied to the attenuator. The
attenuator is then used to reduce the pulse 10 db steps.
Intermediate values aL amplitude may be selected by means of the AMPLI-
TUDE control which has a continuous range of more than 10 db.
This control consists of two ganged variable resistors which vary the
grid bias and plate voltage on the output amplifier tube V11 and the cath-
ode voltage on the two clipper tubes V7 and V9.
In order to provide a more constant pulse output amplitude with changes
in repetition rate and pulse width, a compensation circuit is incorporated
in the unit. When the rate or pulse width is increased, a positive volt-
age is applied to the cathode of V15 through R51 which causes the voltage
to the plate of the output tube and bias of the clippers to increase thereby
compensating for the otherwise decrease in output amplitude when the
rate or pulse width is increased.
The power supply circuits are conventional, and the direct current supply
voltages are regulated either by glow discharge type regulator tubes (V4,
V12, VL4) or by electronic regulators (VlOB, VL7A, V17B). Tubes VlOF
and V17B are used to regulate the t300V supply. Tubes V15 andV17 re-
gulate the voltage supplied to the clipper and output amplifier circuits. |
ACEC
