TM 11-6625-3053-14
SECTION III.
PRINCIPLES OF OPERATION
1-15.
PRINCIPLES OF OPERATION.
Consult Figure 1-3 which refers to items noted in explanation.
a. The heart of the AN/USM-213B is the klystron oscillator (Item A ) which produces signals
from 800 MHz to 2400 MHz.
1. Signal produced by klystron tube in cylindrical cavity of variable resonant internal length.
a)
Klystron tube powered by 4 different power supplies (Item B ).
-750V Repeller.
-325V Beam.
+6V Filament.
Grid Supply.
The repeller and beam supplies are regulated by the Al osc regulating assy (Item C ).
b)
Frequency control ganged linearly with rotation of three key elements.
Frequency cam (Item D ).
Frequency readout on front panel.
Repeller pot (Item E ) determines repeller voltage on klystron tube.
c)
Power Set Probe (Item F ). Penetration is variable and controlled by front panel POWER
SET control.
At a given frequency, POWER SET control adjusts penetration of power set probe to register
1 mW or SET or "0" on front panel POWER MONITOR meter. This is called POWER
At same time, attenuator hairline (Item G ) seeks correct position relative to attenuator dial.
Attenuator Probe (Item
H
).
Penetration is variable and controlled by front panel
ATTENUATOR control.
Output goes to the front panel RF OUTPUT jack.
At same time, attenuator dial (Item I ) shows attenuation reading at hairline corresponding
to depth of probe in cavity. Attenuator dial is linear and graduated in dBm and microwatts.
RF MONITOR Probe (Item
J ) is fixed. Output goes directly to rear panel RF MONITOR
jack.
NOTE
When producing a signal at a fixed frequency, the
operator POWER SETS the instrument as in 1-c above
before setting the attenuator dial at a given power output
level.
If signals at a given power output level must be
simulated at different frequencies or over a frequency
range, the leveling circuits are put into play.
1-8