31
c. Control Settings.— During the entire alignment procedure the receiver controls must be set
as follows unless otherwise indicated:
(1) Squelch Control ................................................... . Maximum CCW..
(2) Audio Gain
...................................Maximum CCW,
(3) Function Switch .....................................................Place in 200 Kc. FM position.
(4) Mon (AGC) rotary switch......................................Place in OFF (MAN) position.
(5) RF GAIN Control ..................................................Set maximum CCW.
“Master” 200 Kc. IF Channel Alignment
Turn on power. Set receiver tuning dial to lowest frequency and remove local oscillator tube
V-204 in the “Master” Tuner.
d. Second Limiter, Adjustment of T-507.— Remove second IF amplifier V-502 from its
socket. Connect the scope to second limiter grid (pin 1 of V-504).
Connect the sweep generator between first limiter grid (pin 1 of V-503) and ground on the
tube socket mounting strap nut. Set the sweep generator output to maximum. Adjust T-507
for a symmetrical response centered around the center frequency marker at 21.4 Mc.
e. Discriminator, Adjustment of T-508.- Remove the first limiter V-503 from its socket.
Connect the sweep generator between pin 1 of V-504 and ground on the tube socket mounting
strap nut. Set the sweep generator output to maximum, Adjust the discriminator transformer
T-508 for a Symmetrical S-shaped discriminator curve, centered around 21.4 Mc.
The discriminator peak-to-peak separation should be 750 Kc, plus or minus 30 Kc.
The adjustments for equal amplitude of the two peaks should be made with the marker
disconnected to prevent base-line shift.
f. First Limiter, Adjustment of T-505, and T-506- Replace V-502 and V-503. Remove V-501.
Connect the scope to first limiter grid (pin 1 of V-503). Connect the sweep generator between
pin 1
of the second IF amplifier V-502 and ground on the tube socket mounting strap nut. Set
the sweep generator to produce a peak scope deflection of 0.25 Volts. Adjust T-505 (primary)
and T-506 (secondary) for a symmetrical response curve centered around 21.4 Mc. The shape
of the response curve should be flat-topped or slightly double-peaked.
Summary of Contents for G-187
Page 7: ...7 Figure 1 1 Model G 187 Special Purpose Receiver Front View...
Page 9: ...9 Table 1 2 Semiconductor and Tube Complement...
Page 10: ...10 Table 1 2 Semiconductor and Tube Complement continued...
Page 14: ...14 Fig 2 1 Block Diagram Model G 187 Receiver...
Page 44: ...44 Fig 4 1 Model G 187 Receiver Top View Cover Removed...
Page 45: ...45 Fig 4 2 Model G 187 Receiver Bottom View Covers Removed...
Page 46: ...46 Fig 4 3 Model G 187 Receiver Rear View...
Page 47: ...47 Fig 4 4 Model G 187 Receiver Panoramic Top View Cover Removed...
Page 48: ...48 Fig 4 5 Model G 187 Receiver Panoramic Top View Left Side Cover Removed...
Page 49: ...49 Fig 4 6 Model G 187 Receiver Panoramic Top View Right Side Cover Removed...
Page 50: ...50 Fig 4 7 Model G 187 Receiver Panoramic Bottom View Covers Removed...
Page 51: ...51 Fig 4 8 Model G 187 Receiver Panoramic Bottom View Left Side Covers Removed...
Page 52: ...52 Fig 4 9 Model G 187 Receiver Panoramic Bottom View Right Side Covers Removed...
Page 53: ...53 Table 4 2 Model G 187 Receiver Component Boards Lists...
Page 54: ...54 Fig 4 10 Model G 187 Receiver Large Component Board...
Page 56: ...56 Fig 4 14 Model G 187 Receiver Master Slave RF Tuners Top View...
Page 57: ...57 Fig 4 15 Model G 187 Receiver Master Slave Tuners Bottom View Covers Removed...
Page 58: ...58 Fig 4 16 Model G 187 Receiver Master Slave Tuners Panoramic Bottom View Covers Removed...
Page 59: ...59 Fig 4 17 Model G 187 Receiver Master RF Tuner Bottom View Cover Removed...
Page 60: ...60 Fig 4 18 Model G 187 Receiver Slave RF Tuner Bottom View Cover Removed...
Page 67: ...67 Fig 5 1 Model G 187 Receiver Schematic Diagram Master RF Tuner...
Page 68: ...68 Fig 5 2 Model G 187 Receiver Schematic Diagram Slave RF Tuner...
Page 71: ...71 Fig 5 5 Model G 187 Receiver Schematic Diagram Main Chassis Circuits...
Page 72: ...72 Fig 5 6 Model G 187 Receiver Schematic Diagram Mainframe...
Page 73: ...73 Fig 5 7 Model G 187 Receiver Schematic Diagram Power Supply Circuits...
Page 74: ...74 Fig 5 8 Model G 187 Receiver Schematic Diagram Various Details...
