Section IV. CIRCUIT DESCRIPTIONS
First Stage Amplifier Circuits
(2) The cryogenic temperature is measured
Vacuum Vessel Module 2A3 (fig. 2-8).
by a gold-iron thermocouple, which is part of Unit 4. The
(1) The first stage of the parametric amplifier
voltage output of the thermocouple is connected to J1
(Module 2A3) consists of an RF circuit that is operated at
terminals 1 and 2. At operating temperature (18 2K)
a cryogenic temperature. Module 2A3 is operating
the voltage is in the range 2.5 to 7.5 mV. This voltage is
satisfactorily when an RF input signal in the range 7250
amplified in Unit 1 sufficiently to drive the CRYOGENIC
to 7750 MHz at a power level of - 50 dBm or less has a
TEMP meter 1M1.
gain of about 15 dB at the RF output terminal when the
(3) Vacuum gage tube (J2) can be operated
module is at the specified cryogenic temperature. The
only in conjunction with the VACUUM meter (1M2) circuit
operator cannot adjust any part of the internal RF
in Unit 1, where test points are available for
circuits; pump filter FL1 and mount circulator AR1
(consisting of a paramp varactor and paramp circulator)
Figure 2-8. Vacuum Vessel Module 2A3, Schematic Diagram.