Power Supply

Reference:    NAVSHIPS 91875(A), para 2l

All voltages necessary for the operation of the AN/SRR-11, -12, or -13 receivers are provided by an a-c operated power supply.  Taps on the primary of transformer T1601, selected by an appropriate position of link O1601 on link board E1601, accomodate either a 105-, 115-, or 125 volt a-c source at frequencies of 50-60 cycles.  Additionally, for operation at 400 cycles, the other side of the primary circuit, which is connected to terminal No. 1 of the power transformer T1601, must be reconnected to terminal No. 6, in which case the line voltage taps function as above.  The two section POWER switch S251 of AN/SRR-11, S451 of AN/SRR-12, or S651 of AN/SRR-13 which is mounted on the front panel, opens and closes both sides of the primary of T1601.  Two fuses, F1601 and F1602, protect the circuit from overload.

Rectified current, developed by V1601 and V1602, is taken from the parallel connected cathodes and fed through a choke-input filter L1601A, L1601B, C1601, C1602.  Two outputs are supplied by the rectifier; 120 volts at terminal J1601C, and 95 volts regulated by V1603 at terminal J1601D.  This is obtained by connecting V1603 to the midpoint of the filtering network by R1603.  C1603 provides r-f filtering of the regulated output.  A visual indication of the existence of B+ is given by the pilot light (I251 of the AN/SRR-11, I451 of the AN/SRR-12, and I651 of the AN/SRR-13) which is located on the front panel and glows when d-c voltage is present in the circuit.  This pilot light (a neon bulb) is connected in series with a 100K resistor R262, R462, or R662 and this series combination is connected across B+.

Two heater windings are provided on the secondary of T1601: One winding (terminals 8, 9) supplies heater voltage for the noise limiter diode, V1101.  This is supplied at a reduced level (5.2 volts) so as to reduce the hum due to the heater-cathode leakage in V1101.  Potentiometer R1601 (a chassis control) adjusts the balance of this winding to further reduce hum when a 400-cycle primary source is employed.   The second heater winding (terminals 10, 11, 12, 13, 14) has several taps on each side of its ground connections.  Most of the heater voltages for all other vacuum tubes in the equipment are supplied from terminals 11 and 13.  Terminal 12 is connected to ground.  A ballast resistor, R1605, is connected in series between terminal 10 of the transformer and one of the oscillator heater leads to regulate current to the oscillator heater.  (The other lead of the oscillator heater is grounded.)  A 6.3-volt a-c potential from terminal 14 of T1601 supplies the dial light and in the AN/SRR-11, additionally, the heaters of V101, V126, and V151.

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