26
This bias is enough to keep the third stage blocked until its grid receives a positive charge
from the second stage The carrier operated relay, K-101, is connected in the third stage plate
circuit and is closed when the tube conducts. Thus the presence of AGC voltage, by causing
the first stage to block and the second stage to conduct, ultimately causes the third stage to
conduct and the relay to close.
When the carrier disappears, causing the second stage to cease conduction, the relay is held
closed for a period of 3 to 13 seconds due to third stage conduction which results from the
fact that capacitor C-113 holds a positive charge on the third stage grid. Since the presence of
diode CR-102 necessitates that this capacitor discharge only through resistor R-145 and COR
DELAY potentiometer R-146, adjustment of this control provides variation of the length of
the time between the loss of the carrier and the transferring of the relay to the carrier-off
position.
The relay has three sets of contacts, two of which are made available for use in the carrier
control of auxiliary equipment by their connection to J-108 on the chassis rear apron.
The third set of relay contact controls the COR panel light so that it is on when a carrier is
present and off when there is no carrier.
The COR light is physically combined with a pushbutton switch, the COR DELAY
DISABLE control, DS-103. When depressed, this switch disconnects one side of capacitor C-
113 from the circuit, no longer permitting the capacitor to delay the carrier-off functioning of
the circuit. This is desirable during sensitivity adjustment of the circuit.
e. POWER SUPPLY
A conventional two-section capacitive input filter power supply delivers a DC potential of
240 volts, while CR-107 and CR-108 (150 V – 10 W Zener diodes) provide two separate 150
VDC regulated outputs.
A 6.3-volt winding supplies the filaments of all tubes except the two V-201 tubes (416B’s) in
the RF Tuners. The two V-201 tubes are supplied by a separate 12.6 VAC winding of the
power transformer T-101 in series with external 5.1-Ohm dropping resistors.
Содержание G-187
Страница 7: ...7 Figure 1 1 Model G 187 Special Purpose Receiver Front View...
Страница 9: ...9 Table 1 2 Semiconductor and Tube Complement...
Страница 10: ...10 Table 1 2 Semiconductor and Tube Complement continued...
Страница 14: ...14 Fig 2 1 Block Diagram Model G 187 Receiver...
Страница 44: ...44 Fig 4 1 Model G 187 Receiver Top View Cover Removed...
Страница 45: ...45 Fig 4 2 Model G 187 Receiver Bottom View Covers Removed...
Страница 46: ...46 Fig 4 3 Model G 187 Receiver Rear View...
Страница 47: ...47 Fig 4 4 Model G 187 Receiver Panoramic Top View Cover Removed...
Страница 48: ...48 Fig 4 5 Model G 187 Receiver Panoramic Top View Left Side Cover Removed...
Страница 49: ...49 Fig 4 6 Model G 187 Receiver Panoramic Top View Right Side Cover Removed...
Страница 50: ...50 Fig 4 7 Model G 187 Receiver Panoramic Bottom View Covers Removed...
Страница 51: ...51 Fig 4 8 Model G 187 Receiver Panoramic Bottom View Left Side Covers Removed...
Страница 52: ...52 Fig 4 9 Model G 187 Receiver Panoramic Bottom View Right Side Covers Removed...
Страница 53: ...53 Table 4 2 Model G 187 Receiver Component Boards Lists...
Страница 54: ...54 Fig 4 10 Model G 187 Receiver Large Component Board...
Страница 56: ...56 Fig 4 14 Model G 187 Receiver Master Slave RF Tuners Top View...
Страница 57: ...57 Fig 4 15 Model G 187 Receiver Master Slave Tuners Bottom View Covers Removed...
Страница 58: ...58 Fig 4 16 Model G 187 Receiver Master Slave Tuners Panoramic Bottom View Covers Removed...
Страница 59: ...59 Fig 4 17 Model G 187 Receiver Master RF Tuner Bottom View Cover Removed...
Страница 60: ...60 Fig 4 18 Model G 187 Receiver Slave RF Tuner Bottom View Cover Removed...
Страница 67: ...67 Fig 5 1 Model G 187 Receiver Schematic Diagram Master RF Tuner...
Страница 68: ...68 Fig 5 2 Model G 187 Receiver Schematic Diagram Slave RF Tuner...
Страница 69: ...69 Fig 5 3 Model G 187 Receiver Schematic Diagram 21 4 Mc 200 Kc BW IF Strip Master and Slave Channels...
Страница 70: ...70 Fig 5 4 Model G 187 Receiver Schematic Diagram 2 5 Mc 40 Kc BW IF Nuvistor Strip Master and Slave Channels...
Страница 71: ...71 Fig 5 5 Model G 187 Receiver Schematic Diagram Main Chassis Circuits...
Страница 72: ...72 Fig 5 6 Model G 187 Receiver Schematic Diagram Mainframe...
Страница 73: ...73 Fig 5 7 Model G 187 Receiver Schematic Diagram Power Supply Circuits...
Страница 74: ...74 Fig 5 8 Model G 187 Receiver Schematic Diagram Various Details...