TM 11-6625-2948-14+P
FUNCTIONING OF EQUIPMENT
GENERAL
to be calibrated directly in dBm and microvolt. The power
set drive system moves the power probe and the hairline of
T h e Signal Generator AN/URM-206 provides spectrally-
the attenuator dial. The power monitor probe couples rf
power from the klystron cavity to the crystal detector and
pure accurately calibrated signals from 7.0 to 11.0 GHz.
power monitor meter. When the POWER SET control is
It consists of Signal Generator SG-1145/URM (top assem-
adjusted for a power monitor indication of CAL, the power
bly) and Modulator MD-1075/URM.
monitor probe is coupled to approximately 1 milliwatt
p o w e r level. The ATTENUATOR control operates the
attenuator probe and the dBm-microvolts dial to provide a
calibrated rf output.
The SG-1145/URM is a signal-generating device that em-
p l o y s a klystron oscillator with an external cavity to
The signal generator incorporates a provision for automatic
generate rf energy. The frequency range of the signal
F control
frequency stabilization. A sample of power in the klystron
generator is from 7.0 to 11.0 GHz, with a
offering 1.5 MHz fine tuning over the frequency range.
o s c i l l a t o r is fed to an external control system and the
The signal generator has a calibrated piston attenuator with
output of the external control system is fed to the klystron
repeller as a stabilizer input (correction voltage) which is
a 50 ohm output impedance and offers an output range of
0 to - 127 dBm.
superimposed on the repeller voltage.
BLOCK DIAGRAM ANALYSIS, SIGNAL
CIRCUIT ANALYSIS
GENERATOR SG-1145/URM
The signal generator, Fig. 3-1, consists of nine principal
circuit elements: a klystron oscillator, its repeller tracking
system, a beam power supply, a repeller power supply, a
40V power supply for modulation circuits, a Schmitt
A klystron oscillator (1V1) provides the rf power output.
trigger, a square wave generator, a line frequency sine wave
it is velocity-modulated, operating in an external resonant
voltage circuit, and an amplifier circuit. The klystron oscil-
coaxial transmission line and consists of two conductors,
lator employs a reflex klystron tube that is mounted into
one inside the other. The klystron is mounted at one end
an external coaxial cavity, which is tuned to resonance by
of the cavity with the outer cylinder making contact with
a non-contacting short tuning plunger driven by the FRE-
QUENCY GHz control. The frequency drive system also
the first grid and the inner conductor making contact with
operates the digital readout frequency dial and the tracking
the second resonator grid. The resonant circuit is completed
system. which selects the proper repeller mode and adjusts
at the other end of the cavity by a moveable non-
the repeller voltage for the frequency selected. The power
conducting shorting plunger. The position of this plunger
determines the resonant frequency of the cavity. The
supplies are completely solid-state using monolithic linear
i n t e g r a t e d circuits as precision voltage regulators. The
frequency of oscillation of the klystron oscillator is deter-
Schmitt trigger followed by the amplifier delivers the
mined by the resonant frequency of the cavity and the
square wave and pulses to the klystron oscillator. The
magnitude of the repeller voltage. For a given setting of
square wave generator is a D-type flip-flop (1A3U4) whose
the cavity, there is an optimum repeller voltage that will
cause the bunched electrons to return to the resonator grids
variable frequency is controlled by a timer (1A3U3) from
950 to 1050 Hz, minimum, The signal generator incorpo-
at the proper time. The repeller voltage, therefore, cannot
rates a power monitoring circuit that enables the attenuator
remain the same over the frequency range of the oscillator.