TM 11-5820-801-30
cates total hours and tenths of hours that primary voltage
STAGE and SECOND STAGE, on the front panel of Unit
has been applied to 1PS1 (fig. 2-1). The meter dial has
1 permit measurement of the bias voltages to the 2A3
a digital movement; that is, the 0.1-hour indicator moves
paramp varactor and the 2A2 paramp varactor (fig. 2-1).
once in 6 minutes and the hour indicator advances one
The voltage will be in the range 3 3 V. The precise
unit each hour. Klystron oscillator 2A1V1 is a limited life
item (5000 hours, minimum). The purpose of 1M3 is to
permit maintenance personnel to determine easily
indicate when 2A1V1 is approaching its expected life
whether bias voltage is present in Unit 1 and therefore
limit.
(assuming circuit continuity) at the paramp varactors in
d. VARACTOR VOLTAGE TEST Points. Two
Modules 2A2 and 2A3. The presence or absence of bias
monitor points, VARACTOR VOLTAGE TEST FIRST
voltages is an important maintenance factor.
Section II. INTERNAL TEMPERATURE CONTROLS
the vacuum at a much lower pressure than that initially
2-9. Vacuum Vessel Module 2A3 Temperature
obtained by operating the vacuum pump during
a. General.
The interior of Vacuum Vessel
preliminary adjustment procedures.
Thus a hard
Module 2A3 is operated at an ambient temperature of
vacuum indicates suitably low temperature and
about 18K (- 427F). This is accomplished by use of a
unsatisfactorily high temperature results in a soft
closed cycle Helium Refrigerator, Unit 4, of which
vacuum. Unit 1 monitors are used to indicate the internal
Refrigeration Unit Assembly 4A3 is inserted into 2A3. A
cryogenic temperature (CRYOGENIC TEMP meter 1M1)
vacuum is used to insulate the cold parts of 2A3 (and
and pressure (VACUUM meter 1M2) in 2A3 (fig. 2-2).
4A3). Because the cryogenic temperature is well below
the freezing point of air, the temperature helps maintain
Figure 2-2. Block Diagram of Module 2A3 Temperature and Pressure Sensors.
b. CRYOGENIC TEMP Meter 1M1. Refrigerator Unit
One is a hydrogen bulb that operates a hydrogen
pressure gage (temperature gage) mounted on
Assembly 4A3 (fig. 2-2) has two independent
temperature sensors.
2-5
