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LTV G-187 Instruction Book

Special purpose receiver
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INSTRUCTION BOOK
FOR
MODEL G-187 SPECIAL PURPOSE RECEIVER
LTV - Electrosystems, Inc.
(A Subsidiary of Ling-Temco-Vought)
TEMCO Aerosystems Division
P.O. Box 1056
Greenville, Texas 75402

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  • Page 1 INSTRUCTION BOOK MODEL G-187 SPECIAL PURPOSE RECEIVER LTV - Electrosystems, Inc. (A Subsidiary of Ling-Temco-Vought) TEMCO Aerosystems Division P.O. Box 1056 Greenville, Texas 75402...

  • Page 2: Warning & Notice

    NOTICE This is not the original Istruction Manual of the LTV G-187 Receiver, it is only an attempt to write one from scratch (but for sure it is very close to the original manual however).

  • Page 3: Table Of Contents

    1. PURPOSE OF EQUIPMENT............……… 11 2. DESCRIPTION OF EQUIPMENT ...........……… 11 SECTION 2 - THEORY OF OPERATION 1. ANALYSIS, MODEL G-187 RECEIVER……………………………………15 2. “MASTER” AND “SLAVE” RF TUNERS........………...16 a. Antenna Inputs ................………..16 b. First RF Stage ("Master or "Slave" Tuner)……………………………….16 c.
  • Page 4 2. CONTROL SETTINGS ..............………..28 Power ..................………..28 b. Function Switch...................28 c. Squelch......................28 d. Audio Gain....................28 SECTION 4 - MAINTENANCE 1. INTRODUCTION ....................29. 2. IF ALIGNMENT PROCEDURE (Sweep Method) General Instructions.................30 Equipment Required ..............………..30 Control Settings .......
  • Page 5 Receiver COR Circuit, Simplified Schematic........ ……… 24 Model G-187 Receiver, Top View (Dust Cover Removed)... ……… 44 Model G-187 Receiver, Bottom View (Dust Cover Removed) ..……… 45 Model G-187 Receiver, Rear View ..........……… 46 Model G-187 Receiver, Panoramic Top View (Cover Removed)………... 47 Model G-187 Receiver, Panoramic Top View Left Side (C.
  • Page 6 Schematic Diagram: Power Supply Circuits………………………………… 73 Schematic Diagram: Various Details…………………………………………74 LIST OF CHARTS AND TABLES Table Title Pages Performance Specifications ............………. 8 Semiconductor and Tube Complement ......... …… 9, 10 Voltage Measurements, Model G-187 Receiver ......…… 42, 43 Parts List............(currently under construction)

  • Page 7: Model G-187 Special Purpose Receiver, Front View

    Figure 1-1. Model G-187 Special Purpose Receiver, Front View...
  • Page 8 PERFORMANCE SPECIFICATIONS Model G-187 Receiver Tuning Range 55-260 Mc. IF Rejection 70 dB, minimum Image Rejection 58 dB, minimum Noise Figure 6 dB, maximum Absolute Sensitivity 4 uV produces at least 23 db S/N with 100 kc deviation, 1 kc modulation frequency.

  • Page 9: Semiconductor And Tube Complement

    Table 1-2. Semiconductor and Tube Complement.

  • Page 10: Semiconductor And Tube Complement

    Table 1-2. Semiconductor and Tube Complement (continued).

  • Page 11: Section 1 - General Description

    1-1, Performance Specifications. 2. DESCRIPTION OF EQUIPMENT The Model G-187 receiver is 7 inches high by 19 inches wide by 19-7/8 inches deep and it weighs approximately 40 pounds. Panel and chassis are of aluminum construction, and the front panel has a black plexiglass outer covering with aeronautical-style grazing light lamps mounted on it.
  • Page 12 The tuning dial on the G-187 receiver series is a spiral scale printed on 1/8" thick translucent plastic disk illuminated from behind. A small crescent-shaped window mask, sliding vertically, tracks each spiral showing on the relevant part as the radio is tuned.
  • Page 13 The G-187 receiver is not intended for CW reception and so it is not equipped with a BFO. It is also worth to say that the audio output of the G-187 receiver is at a very low level; for sure this receiver requires an external audio amplifier associated to a good speaker for a comfortable listening.

  • Page 14: Block Diagram, Model G-187 Receiver

    Fig. 2-1. Block Diagram, Model G-187 Receiver.

  • Page 15: Section 2 - Theory Of Operation

    THEORY OF OPERATION 1. ANALYSIS, MODEL G-187 RECEIVER a. A block diagram of the Model G-187 receiver is shown in Figure 2-1. The circuit, with the function switch in the 200 Kc AM or FM position is a single superheterodyne with an IF of 21.4 Mc. With the function switch in the 40 Kc AM or FM position, a dual-conversion circuit is used, with a 21.4 Mc first IF, followed by a 2.5 Mc...

  • Page 16: Master" And "Slave" Rf Tuners

    The IF amplifiers, with the function switch in the 200 Kc. FM position, use two stages of amplification, cascade limiters and a phase-shift discriminator. With the function switch in the 200 Kc. AM position, AGC voltage is applied to the first two stages, and the second limiter becomes the AM detector.

  • Page 17: Second Rf Stage ("Master" Or "Slave" Tuner)

    To prevent loss of input signal due to cathode-to-filament capacity, the filaments are kept above RF ground with broad-band chokes. The input resistance of the 416B is approximately equal to 2/Gm when RL = RP, and in this case is 40 Ohms. The cathode circuit is not tuned, due to the extreme bandwidth produced by the 40-Ohm shunt load and the low cathode-to-ground capacity.

  • Page 18: Mixer ("Master" Or "Slave" Tuner)

    A blower motor mounted on the front end assembly is used to cool the 416B tube. The motor plugs into the main chassis with a Jones plug. A jumper between two of the pins of the Jones plug removes plate voltage from the 416B when the motor is disconnected, thus protecting the tube.

  • Page 19: Oscillator Buffer ("Slave" Tuner Only)

    f. OSCILLATOR BUFFER (“SLAVE” TUNER ONLY) A 6AK5 pentode is used in this stage as “oscillator buffer”, in order to avoid any loading effect to the oscillator itself. 3. IF STAGES The first 21.4 Mc IF transformers, located on the 200 Kc. IF subassembly (T-302 in the “Master”...

  • Page 20: Function Switch In 200 Kc Am Position, Master If Channel

    b. FUNCTION SWITCH IN 200 Kc AM POSITION, MASTER IF CHANNEL The first two high-gain 6DC6 remote cutoff amplifiers (V-501, V-502) receive an AGC voltage developed at the grid of the 6AK5 (V-504) AM detector. The third IF amplifier (V- 503) which drives the AM detector is not gain controlled but its signal handling capabilities have been improved by increasing the screen voltage.

  • Page 21: Function Switch In 40 Kc Am Position, Master If Channel

    In FM mode, V-610 (7587) acts as the first limiter and V-611 (7587) as the second limiter, while two solid-state diodes (CR-602 and CR-603) form the discriminator circuit. e. FUNCTION SWITCH IN 40 Kc AM POSITION, MASTER IF CHANNEL Plate and screen voltage are removed from both the channels of the 21.4 Mc IF amplifier subchassis and a 21.4 Mc signal is coupled from T-602 to the grid of V-606 (6CW4), that together with V-607 (6CW4) forms a 2.5 Mc cascode mixer.

  • Page 22: Other Circuits

    4. OTHER CIRCUITS a. VIDEO The output of the “Master” channel of the IF strips (200 or 40 Kc) drives one half of a 12AU7A direct-coupled video amplifier (V-101A). A zero center scale meter (M-102) is used as a tuning indicator and is connected in a bridge circuit consisting of the video amplifier and the other half of the 12AU7A (V-101B).

  • Page 23: Receiver Squelch Circuit, Simplified Schematic

    Fig. 2-2. Model G-187 Receiver Squelch Circuit, Simplified Schematic. When receiving amplitude-modulated signals with a high percentage of modulation, the squelch circuit may be cut off on negative modulation peaks when the envelope amplitude becomes zero. To prevent this, a filter consisting of R-126 and the .01 uF cap is placed between the limiter and the grid of the d-c amplifier.

  • Page 24: Audio Amplifier

    J-108, a socket on the chassis rear apron. Fig. 2-3. Model G-187 Receiver COR Circuit, Simplified Schematic. The relay is actuated when a carrier of adequate strength is received.
  • Page 25 The sensitivity of the circuit to varying levels of carrier strength is adjustable by means of a panel mounted COR SENS control and a panel mounted COR DELAY DISABLE control is available to remove the delay of the carrier-off action while adjusting sensitivity. The circuit accomplishes control of the relay by the carrier through the use of three stages of DC amplification, the first being voltage-controlled by AGC and the last actuating the relay.

  • Page 26: Power Supply

    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.

  • Page 27: Signal Strength And Tuning Meters

    f. SIGNAL STRENGTH AND TUNING METERS The signal strength meter, M-101, indicates the relative strength of the carrier being received by reading the value of the AGC voltage with respect to ground; it works both in AM and in FM mode. During FM reception only, the TUNING meter, M-102, indicates the accuracy of the receiver tuning.

  • Page 28: Section 3 - Operation

    Since operating instructions for the receiver depend largely on system integration, a complete discussion of receiver operation is not presented here. However, Figure 1-1 shows the appearance and location of controls on the front panel of the Model G-187 Special Purpose Receiver.

  • Page 29: Section 4 - Maintenance

    Bandwidth Nuvistor subchassis and provided with a four-position Function switch (40 Kc AM/40 Kc FM/200 Kc AM/200 Kc FM). With certain reservations, however, these illustrations will serve to represent all versions of the Model G-187 receiver, since all of them have identical chassis and sub-assemblies.

  • Page 30: If Alignment Procedure (Sweep Method)

    2. IF ALIGNMENT PROCEDURE. (Sweep Method) a. General Instructions.— In order to minimize the frequency response of the detectors (including their decoupling networks) used for visual alignment, the sweep generator sweep width used should be no greater than that required to produce the desired oscilloscope pattern. The marker generator signal at 21.4 mc should be coupled in as required to produce a suitable marker pip.

  • Page 31: Control Settings

    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.

  • Page 32: Second If Amplifier, Adjustment Of T-503 And T-504

    g. Second IF amplifier, adjustment of T-503 and T-504.— Replace V-501. Disconnect the cable connected to J-202 on the RF chassis. Connect the scope to first limiter grid (pin 1 of V- 503). Solder a 10 Ohm resistor between pin 1 of V-501 and ground of the tube socket mounting strap nut.

  • Page 33: Second If Amplifier, Adjustment Of T-303 And T-304

    nut. Set the sweep generator to produce a peak scope deflection of 0.25 Volts. Adjust T-305 (primary) and T-306 (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. f.

  • Page 34: 2.5 Mc. If Amplifier

    been carefully done at the Factory and no further attempt should normally be required. e. 2.5 Mc. IF Amplifier.- Connect a 21.4 mc marker signal to control grid of V-606 and tune L-608, L-610 and L-611 for a maximum indication of the Signal Strength meter, M-101, on the front panel.

  • Page 35: Mechanical Adjustments

    b. Mechanical Adjustments.— Normally the tuning dial will not need any adjustment in the field, however, if the above procedure fails to restore normal operation, refer to the following: (1) Loosen both stops of the tuning mechanism.. (2) Rotate dial to the extreme low-frequency end until the dial is stopped by the inductuner stop of BOTH the “Master”...

  • Page 36: If Alignment (Cw Method)

    (6) Adjust C-220 for a 15% dip in the response. (7) Repeat (5) above. (8) Set dial to 250 Mc. and bend end inductors L-207 and L-209 to produce a symmetrical response centered at 250 Mc. Use 250 Mc. marker. (9) Unsolder C-248 from the BNC test connector and resolder to the inductuner.

  • Page 37: Discriminator Alignment - (Cw Method)

    (6) Increase the signal generator output to produce approximately the same value on the VTVM as in (4) above. (7) Adjust the secondary slug of T-507 for a maximum reading on the VTVM. (8) Adjust the primary slug of T-507 for a maximum reading, keeping the signal generator output adjusted for the same value on the VTVM as in (4) above.

  • Page 38: If Amplifiers (Cw Method)

    (9) Detune the signal generator above and below 21.4 Mc. to produce a maximum positive and negative output. These voltages should be equal and have a magnitude of approximately +/- 8 Volts, D.C. Minor adjustment of the primary of T-508 will cause the two peak voltages to become exactly equal.

  • Page 39: Slave" 200 Kc. If Channel Alignment

    (9) Increase the signal generator output to produce 2 V on the VTVM, (10) Adjust the secondary (T-506) for maximum reading on the VTVM. (11) Adjust the primary (T-505) for maximum reading, keeping the signal generator output adjusted to maintain 2 V on the VTVM. DO NOT readjust the secondary (T-506) for a maximum as this will result in improper adjustment.

  • Page 40: Master" 40 Kc. If Channel Alignment

    (1) Remove the oscillator tube (V-204) to prevent mixing at the signal generator harmonic frequencies. (2) Set the receiver dial to approximately 60 Mc. (3) Set the generator to 21.4 Mc. and connect to pin 1 of V-203. (4) Connect a high-resistance DC voltmeter (VTVM) to the cathode of the detector diode CR- 301.

  • Page 41: Slave" 40 Kc. If Channel Alignment

    “Slave” 40 Kc. IF Channel Alignment b. 40 Kc. Band-Pass Filter. Adjustment of L-602 and L-603.— Set the function switch to 40 Kc. Set the generator to 2.5 Mc. and connect to control grid of V-604 on the nuvistor socket. Connect the VTVM to the grid return of V-605, set the generator output level to approximately 2 V and adjust L-602 and L-603 alternatively for maximum gain.
  • Page 42 200 Kc. IF AMPLIFIER (Master Channel, Function Switch in 200 Kc. FM Position) V-501 6DC6 -0.33 6.3 AC V-502 6DC6 -0.32 0.83 6.3 AC V-503 6CB6 -0.31 0.12 6.3 AC V-504 6AK5 -6.6 6.3 AC V-505 6AL5 -0.22 -7.0 5.8 AC -12.4 Table 4-1. Voltage Measurements, Model G-187.
  • Page 43 Section 4 of this Manual; filament voltages measured between tube pin and chassis except V-201; DC voltages taken with an 11-MegOhm VTVM; all voltage measured with respect to Gnd. Table 4-1. Voltage Measurements, Model G-187 (continued).

  • Page 44: Model G-187 Receiver, Top View (Dust Cover Removed)

    Fig. 4-1. Model G-187 Receiver, Top View (Cover Removed).

  • Page 45: Model G-187 Receiver, Bottom View (Dust Cover Removed)

    Fig. 4-2. Model G-187 Receiver, Bottom View (Covers Removed).

  • Page 46: Model G-187 Receiver, Rear View

    Fig. 4-3. Model G-187 Receiver, Rear View.

  • Page 47: Model G-187 Receiver, Panoramic Top View (Cover Removed)

    Fig. 4-4. Model G-187 Receiver, Panoramic Top View (Cover Removed).

  • Page 48: Model G-187 Receiver, Panoramic Top View Left Side (C. R.)

    Fig. 4-5. Model G-187 Receiver, Panoramic Top View Left Side (Cover Removed).

  • Page 49: Model G-187 Receiver, Panoramic Top View Right Side (C. R.)

    Fig. 4-6. Model G-187 Receiver, Panoramic Top View Right Side (Cover Removed).

  • Page 50: Model G-187 Receiver, Panoramic Bottom View (C. R.)

    Fig. 4-7. Model G-187 Receiver, Panoramic Bottom View (Covers Removed).

  • Page 51: Model G-187 Receiver, Panoramic Bottom View Left Side (C. R.)

    Fig. 4-8. Model G-187 Receiver, Panoramic Bottom View Left Side (Covers Removed).

  • Page 52: Model G-187 Receiver, Panoramic Bott. View Right Side (C. R.)

    Fig. 4-9. Model G-187 Receiver, Panoramic Bottom View Right Side (Covers Removed).
  • Page 53 Table 4-2. Model G-187 Receiver, Component Boards (Lists).

  • Page 54: Model G-187 Receiver, Large Component Board

    Fig. 4-10. Model G-187 Receiver, Large Component Board.

  • Page 55: Model G-187 Receiver, Small Component Board

    Fig. 4-11. Model G-187 Receiver, Small Component Board. Fig. 4-12. Model G-187 Receiver, Auxiliary & Output Circuits (Top View). Fig. 4-13. Model G-187 Receiver, Auxiliary & Output Circuits (Bottom View).

  • Page 56: Model G-187 Receiver, Auxiliary & Output Circuits (Bott. View)

    Fig. 4-14. Model G-187 Receiver, Master & Slave RF Tuners, Top View.
  • Page 57 Fig. 4-15. Model G-187 Receiver, Master & Slave Tuners, Bottom View (Covers Removed).
  • Page 58 Fig. 4-16. Model G-187 Receiver, Master & Slave Tuners, Panoramic Bottom View (Covers Removed).

  • Page 59: Master Rf Tuner, Bottom View (Cover Removed)

    Fig. 4-17. Model G-187 Receiver, Master RF Tuner, Bottom View (Cover Removed).

  • Page 60: Slave Rf Tuner, Bottom View (Cover Removed)

    Fig. 4-18. Model G-187 Receiver, Slave RF Tuner, Bottom View (Cover Removed).

  • Page 61: Mc - 200 Kc. Bw If Strip, Bottom View

    Fig. 4-19. Model G-187 Receiver, 21.4 Mc - 200 Kc. BW IF Strip (Master & Slave Channels), Top View. Fig. 4-20. Model G-187 Receiver, 21.4 Mc - 200 Kc. BW IF Strip, Bottom View (C.R.).
  • Page 62 Fig. 4-21. Model G-187 Receiver, 21.4 Mc - 200 Kc. BW IF Strip (Master & Slave Channels), Bottom View, Input Side. Fig. 4-22. Model G-187 Receiver, 21.4 Mc - 200 Kc. BW IF Strip (Master & Slave Channels), Bottom View, Output Side.
  • Page 63 Fig. 4-23. Model G-187 Receiver, 2.5 Mc - 40 Kc. BW IF Nuvistor Strip (Master & Slave Channels), Top View. Fig. 4-24. Model G-187 Receiver, 2.5 Mc - 40 Kc. BW IF Nuvistor Strip, CEI Label on the chassis side.
  • Page 64 Fig. 4-26. Model G-187 Receiver, 2.5 Mc - 40 Kc. BW IF Nuvistor Strip (Master Channel), Bottom View. Fig. 4-27. Model G-187 Receiver, 2.5 Mc - 40 Kc. BW IF Nuvistor Strip (Slave Channel), Bottom View.

  • Page 65: Controls In The Front Panel (Bottom Side)

    Fig. 4-28. Model G-187 Receiver, Controls in the Front Panel (Bottom Side). Fig. 4-29. Model G-187 Receiver, AGC “MON/DF” and Function Switches in the Front Panel. Fig. 4-30. Model G-187 Receiver, Rear of the Front Panel Function Switch.

  • Page 66: Power Supply Section, Top View

    Fig. 4-31. Model G-187 Receiver, Rear of the AGC “MON/DF” Rotary Switch. Fig. 4-32. Model G-187 Receiver, The Power Supply Section, Top View. Fig. 4-33. Model G-187 Receiver, The Power Supply Section, Bottom View.

  • Page 67: Schematic Diagram: Master Rf Tuner

    Fig. 5-1. Model G-187 Receiver, Schematic Diagram: Master RF Tuner.

  • Page 68: Schematic Diagram: Slave Rf Tuner

    Fig. 5-2. Model G-187 Receiver, Schematic Diagram: Slave RF Tuner.

  • Page 69: Schematic Diagram: 21.4 Mc.- 200 Kc. Bw If Strip

    Fig. 5-3. Model G-187 Receiver, Schematic Diagram: 21.4 Mc.- 200 Kc. BW IF Strip (Master and Slave Channels).
  • Page 70 Fig. 5-4. Model G-187 Receiver, Schematic Diagram: 2.5 Mc.- 40 Kc. BW IF Nuvistor Strip (Master and Slave Channels).

  • Page 71: Schematic Diagram: Main Chassis Circuits

    Fig. 5-5. Model G-187 Receiver, Schematic Diagram: Main Chassis Circuits.

  • Page 72: Schematic Diagram: Mainframe

    Fig. 5-6. Model G-187 Receiver, Schematic Diagram: Mainframe.

  • Page 73: Schematic Diagram: Power Supply Circuits

    Fig. 5-7. Model G-187 Receiver, Schematic Diagram: Power Supply Circuits.

  • Page 74: Schematic Diagram: Various Details

    Fig. 5-8. Model G-187 Receiver, Schematic Diagram: Various Details.

  • Page 75: Disclaimer

    DISCLAIMER This manual is provided "as-is", without any express or implied warranties whatsoever. In no event will the author be held liable for any damages, claims or other liabilities direct or indirect, arising from the use of this manual. This manual is free for private use and you are allowed to redistribute it freely, subject to the following restrictions: 1) The origin of this manual must not be misrepresented and you must not claim that you wrote it.

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