1 Theory of Operation ...... 1-1 Line of Sight ...... 1-3 Troposcatter ...... 1-4 Diffraction ...... 1-5 Fading ...... 1-7 Diversity Reception ...... 1-7 Characteristics of AN/TRC-170 (V)2, 3, 5 ...... 1-9 Service Range of the V2, V3 ...... 1-10 2 AC Power ...... 2-1 Power Entry Panel Controls & Indicators ...... 2-3 Low Voltage Power Supply #1 ...... 2-11 Low Voltage Power Supply #2 ...... 2-12 AC-AC Converter ...... 2-14 3 DC POWER ……………………………………………………….3-1 4 TQG Operation ...... 4-1 Fault Indicator Panel ...... 4-6 Generator Switch Over ...... 4-10 5 Signal Flow ...... 5-1 Signal Entry Panel #1...... 5-2 Signal Entry Panel #2...... 5-3 10 OM-71 Tropo Modem (TM) ...... 10-1 Distortion Adaptive Receiver (DAR) ...... 10-4 Receiver Gain Equalization ...... 10-5 Controls and Indicators ...... 10-6 Bit Error Rate (BER) ...... 10-9 TABLE OF CONTENTS (continued)

CHAPTER SUBJECT PAGE

Circuit Card Description ...... 10-13 11 IF Test Panel ...... 11-1 Controls and Indicators ...... 11-3 12 SN-53 Frequency Synthesizer ...... 12-1 Controls and Indicators ...... 12-2 13 AM-7027 Up Converter-Amplifier ...... 13-1 Controls and Indicators ...... 13-2 14 High Power Amplifier...... 14-1 Concept ...... 14-3 Controls and Indicators ...... 14-5 Tuning the Klystron ...... 14-7 High Power Generation...... 14-9 BITE ...... 14-10

a 15 AM-7026 Down Converter-Receiver ...... 15-1 Controls and Indicators ...... 15-2 16 ALARM MONITOR and RAAM...... 16-1 Alarm Monitor ...... 16-2 Antenna Monitor ...... 16-8 RAAM Controls and Indicators ...... 16-11 17 Antenna ...... 17-1 18 Orderwires ...... 18-1 DVOW ...... 18-2 ROCU ...... 18-4 AVOW ...... 18-6 19 Loopbacks ...... 19-1 Channel ...... 19-3 Group ...... 19-6 Supergroup ...... 19-12 20 Link Establishment ...... 20-1 21 Configurations ...... 21-1 22 Operational Verification ...... 22-1

APPENDIX SUBJECT PAGE

A Cross Reference Guide ...... A-1 B Miscellaneous Information ...... B-1 Baseband Patch Panel ...... B-2 AN/TRC-170 Meter Readings ...... B-3 Power Conversion Chart ...... B-5

b Chapter 1 Theory of Operation

CHAPTER 1

Theory of Operation

Dimensionless Variable v = 18.68



r o2 fr r o1 r o2 + o1 fr 1 r o1 r o2 12 f Radius of the first Fresnel Zone = 17.3 R 1

1-1 CECOM LAR Tropo Operation Handbook Basic Theory of Tropospheric Scatter Communications The Earth’s atmosphere is comprised of five layers; Troposphere, Stratosphere, Mesosphere, Thermosphere and Exosphere. Each layer of the atmosphere affects communication signals differently.

The troposphere is the lowest, most dense layer of the atmosphere and extends from the Earth’s surface to an average of 10 km. As you increase height in this layer the temperature drops from 17 to -52 C. Additionally, this is where most of the weather takes place. The tropopause separates the troposphere from the next layer of the Earth’s atmosphere. The troposphere and tropopause together are known as the lower atmosphere. The name troposphere is derived from the Greek tropein, which means to turn or change. With today’s technologies we are able to predict many conditions in the troposphere and use this Figure 1- 1 Atmosphere natural medium to transmit and receive microwave energy. Tropospheric scatter is one method of propagating (transmitting) microwave energy beyond Line of Sight (LOS) or over the horizon. It takes advantage of the refraction and reflection phenomena in the troposphere. Microwave signals are scattered in such a way as to allow reliable communications on hops up to 640 km (400 miles). The Department of Defense uses smaller mobile communication systems to provide battlefield communications. The range of these systems is typically 100-150 miles. There are a number of theories explaining Tropospheric scatter communications ending with a small fraction of the transmitted radio energy being diverted towards a receiving station. One theory is that the diversion is caused by atmospheric air turbulence, irregularities in the refractive index, or similar rapid change in the meteorological elements. This theory accounts for the scattering of radio energy like fog or moisture seems to scatter headlights on a dark night. Another theory is that the air is stratified into discrete layers of varying thickness in the troposphere. The boundaries between these layers become partially reflecting surfaces for radio waves and thereby scatter the waves downward over the horizon. Regardless of the theory you choose to accept, it is undeniable that reliable, effective communications are established using this method. Tropospheric Scatter Communications can be puzzling and frustrating. Once you understand the mechanics of this type of communication system, it is actually simple and easy to work with. There are a number of terms and definitions you should understand to be an effective Tropo Communicator. These terms are explained in the proceeding pages of this chapter.

1-2 Chapter 1 Theory of Operation PROPAGATION: The dictionary defines propagation as; “transmission (esp. sound waves or electromagnetic radiation) through a medium”. The medium in this case is the Troposphere. There are three propagation modes of operation for the AN/TRC-170. These three modes are: LOS, Tropo, and Diffraction, as explained in detail below.

Line-Of-Sight (LOS)

Figure 1- 2 Line of Sight Ray Path As depicted above, two stations must have a direct ray path between the antennas. Generally, LOS is used no more than 35 miles (57 Km). Substantially less transmit power is required for LOS propagation. The most important factor in LOS communications is the First Fresnel Zone.

Figure 1- 3 First Fresnel Zone

FIRST FRESNEL ZONE- The transmitted signal from the antenna is not a straight- line. It is actually closer to that of a cone. The Fresnel Zones are an infinite number of signals that are broadcast out of the antenna. The zones vary in signal strength and phase. Fortunately we are only concerned with the first Fresnel Zone, which is depicted by the gray area in the figure above. This area should be 60% free of obstructions. In the diagram above, if the antennas were 30 miles apart the height of the First Fresnel Zone at 15 miles is 54 feet in diameter. Ideally, 32 feet of this should be clear of obstructions. To complicate matters some obstructions can actually increase the signal several decibels (dB). These factors must be considered during the planning stages. You should be aware of what the First Fresnel Zone is.

1-3 CECOM LAR Tropo Operation Handbook

Troposcatter (Tropo)

Figure 1- 4 Troposcatter Communication Link You will find the Troposcatter or Tropo mode is the most used application for this system. The distorted figure above depicts a typical Over-the-Horizon communication network. Several terms are used when discussing Tropospheric Scatter Communications. We will explain a few of these complex and often misunderstood terms.

COMMON VOLUME: Due to the angle required for successful communications only a certain portion within the troposphere will cause the scattering effect needed between two stations. The intersection of the antenna beams from both stations is referred to as the Common Volume. For best communications, common volume should exist near the mid- point between the two stations.

SCATTER ANGLE: The angle of the two antenna beams interception is referred to as the Scatter angle. The smaller the angle, the more energy that will be scattered from the Common Volume into a receiving antenna. When the angles are too great, little to no energy is diverted to the receiving station. For this reason, the take-off-angles should be as close to 0 (zero degrees) as possible. This will also create the largest Common Volume, which is desirable for more reliable communications.

MULTI-PATH DELAY SPREAD: Fractional amounts of the transmitted signals in the Common Volume are diverted to the receiving station. This results in the same signal being received at different times. This is referred to as Multi-Path Delay Spread. It causes

1-4 Chapter 1 Theory of Operation distortion on the recovered signal. If the Multi-Path Delay Spread is too great, it will prevent recovery of the received signal. The receiving station will see a large Receive Signal Level (RSL) and a high Bit-Error-Rate (BER). The AN/TRC-170 is designed to use the Multi-Path Spread to enhance communications. However if the Multi-Path Spread is too great it will adversely effect communications.

DOPPLER SPREAD: The troposphere is turbulent and causes the transmission path length to slightly change. This in turn causes frequency shifts on portions of the transmitted signal. The magnitude of this spread increases as the air in the common volume becomes more turbulent.

PATH LOSS: Only a fraction of the transmitted energy (signal) arrives at the receiving station. A numeric value is given to the amount of signal that is lost through the troposphere. This value is referred to as Path Loss and is expressed in decibels (dB). The distance between stations (Path Length) will also affect the Path Loss. The allowable path losses for the AN/TRC-170 TROPO system are between 200 and 250 dB. The effect of too much path loss is little or no Receive Signal Level (RSL).

Diffraction The dictionary defines diffraction as: “the spreading of a wave motion, as light, as it passes an obstacle and expands into the region that is behind the obstacle and hence not directly exposed to the incoming waves”. Many Tropo Communicators will never see this type of propagation used or planned. It depends on your area of operation. Military units in the Southwestern United States use this routinely. There are four conditions, which classify a Tropo Radio as diffraction. They are explained below:

Figure 1-5 Diffraction with a single horizon

1. In Figure 1-5 above we see the classic Diffraction propagation. Both stations share a common horizon. The transmit signals are directed at the top of the obstacle. The signal is then diffracted over to the receiving station. A rule of thumb is the obstacle should be approximately 2/3 and 1/3 the distance between stations. As an example; if the distant between stations was 90 miles. One station should be approximately 60 miles from the mountain; the other should be 30 miles.

1-5 CECOM LAR Tropo Operation Handbook

Figure 1-6 Reduced Fresnel Zone Diffraction

2. Figure 1-6 depicts LOS propagation with less than 60% clearance of the first Fresnel Zone. Because of the inverse bending, a LOS path may at times become a diffraction path. It is possible to have Diffraction propagation and not realize it until close examination of the terrain between stations.

Figure 1-7 Diffraction with two horizons 3. In figure 1-7 we see diffraction propagation with two horizons between which a LOS path exists. This is a more complex diffraction path to calculate and is seldom attempted.

Figure 1-8 Diffraction with Closely Spaced Separate horizons 4. In figure 1-8 we see diffraction propagation with two horizons, which are closely spaced, and no LOS path exists. The path loss for this type of diffraction propagation cannot be calculated. Communication links of this type are unpredictable and test shots should be performed to validate usable locations.

1-6 Chapter 1 Theory of Operation FADING: Because the Troposphere is a turbulent medium, communication links suffer a phenomenon termed as Fading. Fading is the reduction of signal strength at the receiving station. There are two types of Fading classification; Rapid Fading and Slow Fading. These are explained below;

RAPID FADING: The term Rapid Fading is known as Fast Fading or Scintillation Fading and usually comes from the Troposphere itself. The random variation in the Troposphere’s refraction qualities causes this fading phenomenon. It is constantly changing from moment-to-moment and from point-to-point. This is the same mechanism that cause stars to twinkle and distant objects to exhibit “heat shimmer” on hot days. The fast fading will be most pronounced when the atmosphere is well mixed with moisture and turbulence. A well-mixed atmosphere is the normal conditions for best communications. Rapid fading affects all frequencies at different instances in time.

SLOW FADING: This is caused primarily by changes in the variation of refractivity with altitude in the atmosphere that develop gradually over a period of time. The frequency and intensity of slow fading are both subject to seasonal influences. It has a tendency to occur simultaneously at different frequencies and on different paths between stations. Slow fading may cause prolonged loss of communications.

DIVERSITY RECEPTION: The dictionary defines diversity as variety. By receiving more than one signal you have diversity reception. Diversity Reception is used to overcome the effects of Rapid Fading. The AN/TRC-170 has two types of diversity reception available; Dual Frequency Diversity and Dual Space Diversity. These are explained below:

DUAL SPACE DIVERSITY RECEPTION: This is accomplished by adding a second antenna and receiver to the station. The antennas are separated by at least 100 wavelengths (20.8 Feet). This separation causes the two received signals to fade independent of each other. The two fading signals are used to generate a single stable signal. This is the only form of diversity reception available to the AN/TRC-170(V)3.

DUAL FREQUENCY DIVERSITY RECEPTION: This is accomplished by adding a second transmitter and antenna to the station. The second transmitter is used on a separate frequency at least 100 MHz apart. This separation will ensure that Rapid Fading will not affect both frequencies at the same time. The signal recovery circuits can then use the two fading signals to develop one stable signal.

QUAD-DIVERSITY RECEPTION: This is accomplished by combining the above two diversity reception methods along with antenna polarization. Refer to figure 1-9 on page 1-8 for the following explanation. Transmitter 1 & 2, transmit using frequencies F1 & F2 (at least 100 MHz apart). Antenna 1 is transmitting a Horizontally Polarized signal while Antenna 2 is transmitting a Vertically Polarized Signal. These transmitted signals are sent to the receiving station. At the receiving station we have Receive Antenna 3 & 4. Both of these antennas have two feed horns, which are Horizontally, or Vertically polarized. These four receiving antenna feeds are connected to four separate receivers; RCVR 1, RCVR 2, RCVR 3 & RCVR 4. The signals at the receivers

1-7 CECOM LAR Tropo Operation Handbook arrive via four different paths with two different frequencies. These four signals are then sent to a diversity combiner (Tropo Modem). This is the best defense against the effects of Slow Fading. This is the preferred operating mode of the AN/TRC-170(V)2.

Antenna 2 Antenna 1 Vertically Polarized Xmt Horizontally Polarized Xmt F1 F2 X/R RCVR 1 XMTR 2 Modem Tropo RCVR 4 F2

F1 F1 RCVR 3 XMTR 1 X/R RCVR 2 Antenna 2 F2 Antenna 1 Vertically Polarized Xmt Horizontally Polarized Xmt

Figure 1- 9 Quad Diversity Diagram

The AN/TRC-170(V)2/3/5 Troposcatter Communication Terminal. There are 3 versions of the AN/TRC-170 in the field. All versions of the AN/TRC-170 will interface with all of the TRI-TAC and MSE family of equipment’s using Conditioned Di-phase via CX-11230 Coax cable, as well as, some older existing analog systems using Dipulse and Bipolar signal formats. The AN/TRC-170(V)2 is sometimes referred to as Heavy Tropo. It consists of a S- 280 shelter mounted on a 5 Ton vehicle along with two 9.5-foot antennas. The V2 is the only system capable of quad-diversity reception. Fort Huachuca, Arizona has the Army’s only active duty V2 assets. The AN/TRC-170(V)3 is sometimes referred to a Light Tropo. It consists of an S-250 Shelter mounted on a heavy HMMWV. The V3 comes with one antenna referred to as the Quick Reaction Antenna (QRA). This QRA consists of two 6-foot parabolic dishes mounted on a common trailer. The AN/TRC-170(V)5 is used by the Marine Corps and differs only by the antenna. The V5 uses a pair of 8-foot parabolic dishes tripod mounted. The table on page 1-9 details the differences between these three versions of AN/TRC-170.

EQUIPMENT REQUIREMENTS FOR TROPO COMMUNICATIONS: In order to establish and maintain a Troposphere Scatter Communications network, you must have the following four items. 1. High Power- The AN/TRC-170(V)2 has dual 2 KW Klystrons while the V3 has a single 2 KW Klystron as the High Power Amplifiers. 2. High Gain Antennas- The AN/TRC-170(V)2 antenna system is comprised of two 9.5 foot parabolic reflectors. This provides a gain of 40.5 dBi. In contrast, the smaller AN/TRC- 170(V)3 antenna system has a gain of 36.5 dBi from its two 6 foot reflectors. 3. Sensitive Receivers- All versions of the TRC-170 use the same very sensitive receivers. The V2 using four receivers while the smaller V3/V5 use two receivers. 4. Diversity Reception- Because of the atmospheric conditions some type of diversity reception must be used. The V3/V5 can provide Dual Space Diversity. While the V2 has the capability of providing Quad-diversity reception.

1-8 Chapter 1 Theory of Operation

TABLE 1-1 AN/TRC-170 CHARACTERISTICS Item V3 Physical dimensions Shelter S-250, 85” x 79” x 70” Weight 3,100 lb. Primary Power Voltage (all versions) 120/208 VAC, 3 phase, 5 wire Frequency (all versions) 50, 60, or 400 Hz Power Requirements 3 10 kW without ECU 15 kW with ECU Environmental Control 9,000 BTU Optional Frequency Range (all versions) 4.4 to 5.0 GHz Bandwidth 3.5 or 7 MHz Range (nominal @ 2048 KB/s) 100 miles RF Output 1 kW TROPO Mode 1 W LOS Modulation (all versions) QPSK or BPSK Timing Standard (all versions) 10 MHz Rubidium Standard Orderwires (same in all versions) 16 KB/s DVOW, Up to four 2 KB/s DOW and an AVOW Nominal Service Range 100 miles Antennas: OE-511 (QRA) Packed dimensions 159” x 89” x ??” Weight 3,120 lb. Diameter 2 each 6 feet Parabolic Gain 36.5 dBi Beam Width (3 dB) 2.6 Operational Wind Speed 80 mph Survival Wind Speed 100 mph Elevation Adjustment +10 to -10 Azimuth Adjustment 20 Polarization Horizontal/Vertical Set-up times ½ hour Waveguide Feed Loss 0.4 dB Mobility features: Shelter M-923, 5 Ton Truck M-1097 Heavy HMMWV M-720 Dolly set (2.1 ton) Antenna M-923, 5 Ton Truck Trailer mounted M-720 Dolly set Set up & Tear down times 2 persons: 1 hour Multiplexer Equipment: All versions have the same compliment of Multiplexer equipment. LGM (2 each) TD-1235 Loop Group Multiplexer GM (1 each) MD-1026 Group Modem TGM (1 each) TD-1236 Trunk Group Multiplexer LSCDM* (Optional 1 each) MD-1023 Low Speed Cable Driver Modem

* The LSCDM could be installed into the AN/TRC-170. Although seldom used, it physically replaces LGM 2 and electrically replaces GM 4 in the MD-1026.

1-9 CECOM LAR Tropo Operation Handbook

95% Availability 99% Availability 300 300 10-3 BER 10-5 BER

Average Path Length in Miles in Length Path Average Data Rate KB/s

256 200 200

1024

2048 100 4096 100

Average Path Length in Miles

V3 Service Range

1-10

CHAPTER 2

AC Power

2-1 AN/TRC-170 POWER REQUIREMENTS

AN/TRC-170 V3 W/O ECU 10 KW

PRIME POWER FREQUENCY NOMINAL 50,60 OR 400 HZ TOLERANCE 47-62 HZ, 380-420

PRIME POWER VOLTAGE PHASE A 108-132 VAC PHASE B 108-132 VAC PHASE C 108-132 VAC NOTE: WILL SHUT DOWN IF ANY PHASE IS MORE THAN 140 VAC OR LESS THEN 100 VAC, ALL PHASES MUST BE WITHIN 5 VAC OF EACH OTHER.

PRIME POWER NO HPA 1 HPA CURRENT

HPAs IN HIGH POWER, 5 AMPS 30 AMPS EACH PHASE (APPROX.)

Main Circuit Breaker NOMINAL 50,60 OR 400 HZ

TRC-170(V)3 240 V AC, 60 amps, 47-62 Hz or 380-420 Hz

Over/Under Relay K1 Trips the Interior Main Prime Power Circuit Breaker if an over voltage of (140 V AC) or under voltage of (100 V AC) condition exists. As will a 5volt difference between any two phases.

PRIME POWER CABLE PIN OUTS

LINE CABLE CONNECTOR PIN Phase A A Phase B B Phase C C Neutral N Safety Ground 1 G1 Safety Ground 2 G2 Safety Ground 3 G3 Safety Ground 4 G4

2-2 PURPOSE: The Power Entry Panel accepts three 120-volt lines (Phase A, B, and C) along with neutral, and a ground fault protection wire by a 5-wire power cable. Phases A, B, C, and neutral are filtered by RFI Filter FL1 prior to leaving the power entry panel. It also provides power to the Exterior Main circuit breaker, ECU circuit breaker, external convenience circuit breaker, and the Antenna Deicing circuit breaker. It also contains the Surge Protection Faulty Assembly 1A2 that protects against high voltage surges for all three phases as well as neutral. The Power Entry panel is electrically the same and located on the Roadside of the shelter for both the AN/TRC-170(V)2 and AN/TRC-170(V)3 systems. We will cover the Power Entry Panel once, since it is the same in the AN/TRC-170(V)2 and the AN/TRC-170(V)3 TROPO systems. Refer to FIG 2-1. The 3-phase AC power comes into the system on J1 of the Power Entry Panel, which is on the outside of the shelter.

SIGNAL FLOW for the Power Entry Panel, refer to FIG 2-1

CONNECTOR PRIME POWER J1: Prime power 115-volt lines (phase A, B, and C) 50,60 or 400 hertz is applied to J1 of the Power Entry Panel.

SURGE PROTECTION FAULT ASSEMBLY: Uses four Metal Oxide Varistors, one for each phase A, B, C, and neutral. When a high voltage surge has occurred the MOV will short circuit, causing the lamp to light altering the operator that a high voltage surge has shorted the associated MOV. Each phase and neutral has an individual fuse in parallel with the lamps. The surge protection fault assembly is connected in parallel with each input phase and neutral. The system can continue to operate but with out surge protection. This means that if another high voltage spike occurs on that same leg it may damage the equipment.

Transformers T1, T2, T3: The induced input voltage is taken of the main power line via these transformer windings T1, T2, and T3. The 3-phase power and neutral is then routed through line filters FL2 through FL5.

FL2 through FL5: These Radio Frequency Interference (RFI) Filters block any RF signals riding on the AC input and neutral. The output of these RFI Filters is then passed to the Power Distribution Assembly Phase Select monitor metering circuits.

FL1 Line Load RF Filter: This Radio Frequency Interference Filter (RFI) blocks any RF signals riding on the AC input and neutral. The output of this RFI Filter is then passed to the Power Distribution Assembly.

Exterior Main Circuit Breaker CB1: This 3-phase circuit breaker is rated at 50 amps. When activated it passes 3-phases voltage to the ECU Circuit Breaker CB2. It passes Phase A to the External Convenience Outlet Circuit Breaker CB4 and then passes Phase B to Antenna 1 & 2 Deicing Circuit Breaker CB3. This circuit breaker is not required to be on for normal operation of the TROPO system.

ECU Circuit Breaker CB2: Is a 3-phase circuit breaker rated at 35 amps. Receives Phase A, B, and C from the Exterior Main Circuit Breaker. When activated it applies power to the ECU.

2-3

Antenna 1 & 2 Deicing Circuit Breaker CB3: Is a single-phase circuit breaker rated at 5 amps. Receives phase B from the Exterior Main Circuit Breaker. When activated it applies power to the Antennas deicing circuitry.

External Convenience Outlet Circuit Breaker CB: Is a single-phase Ground Fault Interrupt (GFI) circuit breaker. Receives Phase A from the Exterior Main Circuit Breaker. When activated it applies power to convenience outlet. The GFI receptacle compares current flow between the line side and the load side. Under normal operations conditions, current flow between the line side and load side is equal. If a difference is detected between the line side and load side current flow, the GFI receptacle opens the circuit, preventing personnel injury and/or protecting the equipment.

2-4

2-5 FIG 2-1 POWER ENTRY PANEL

POWER ENTRY PANEL

2-6

POWER ENTRY PANEL CONTROLS AND INDICATORS

Item Indicator Description 1 EXTERIOR MAIN - circuit breaker Applies prime power to the shelter exterior and provides overload protection. CB1 is a 3-phase 50-amp breaker. 2 ECU – connector Power connection for environmental control unit (air conditioner) 3 ANT 1 DEICING – connector Connector for antenna 1 de-icing cable 4 CNVC OUTLET – connector Connector for accessory equipment 5 ANT 2 DEICING – connector Connector for antenna 2 de-icing cable 6 PRIME POWER - Connector for 208 Connector for prime power from external VAC 3 phase 50-60 or 400 Hz source. 7 CNVC OUTLET - circuit breaker Applies power to CNVC OUTLET connector and provides overload protection. CB4 is a single-phase 15-amp GFI breaker. 8 ANT 1 / 2 DEICING - circuit breaker Applies power to DEICING connectors and provides overload protection. CB3 is a single-phase 5-amp breaker. 9 ECU PWR – circuit breaker Applies power to ECU connector and provides overload protection. CB2 is a 3- phase 35-amp breaker. 10 GROUND - terminal lug External ground terminal connection for shelter ground.

2-7

PURPOSE: The Surge Protection Fault Assembly uses metal oxide varistors, one for each phase A, B, C, and neutral. When a high voltage surge has occurred the MOV will short circuit, causing the lamp to light alerting the operator that a high voltage surge has shorted the MOV. Each phase and neutral has an individual fuse in parallel with the lamps. The surge protection fault assembly is connected in parallel with each input leg and neutral. The system can continue to operate but with out surge protection. This means that if another high voltage spike occurs on that same leg it may damage the equipment. Refer to FIG 2-1 Power Entry Panel.

Surge Protection Fault Assembly 1A2

2-8 AN/TRC-170(V)3

Refer to FO 2-2a, FO 2-2b, and FO 2-2c. The 3-phase AC power comes into the Power Distribution Panel Assembly from the Power Entry Panel via Radio Frequency Inference (RFI) FL1.

Switch S1 Meter Transfer Switch Phase Select: The induced input is taken off the main power line via transformer windings T1, T2, and T3 associated with the RFI filters FL2 through FL5 in the Power Entry Panel. This input power is used by the Phase Select switch S1 and allows monitoring of the current draw for each input phase by ammeter M3. This switch S1 also allows monitoring of the voltage and frequencies of each input phase by voltmeter M4 and frequency meters, M1 for 50/60 hertz and M2 for 400 hertz. Control Circuit Breaker CB13 protects these meters.

Control Circuit Breaker CB13: Is a 3-phase circuit breaker rated at 5 amps. Receives Phase A, B, and C from the Power Entry Panel. Must be activated for the TROPO system to power up. Applies power to the Over/Under Voltage Relay K1 and Phase Select Switch 1. Provides protection for the meters M1 through M4 and Switch S1. If this circuit breaker opens, it will illuminate the Control CB Tripped Lamp DS1 on the Power Distribution Panel. This Control Circuit Breaker CB13 is on the inside of the Power Distribution panel along with fuse F1.

Over/Under Voltage Relay K1: The K1 Relay Over/Under Voltage Relay Assembly monitors the Voltage and Frequency of the input 3-phase power. The line voltage from each leg to neutral is 120 VAC  10 %. Should any phase exceed 140 VAC or be less than 100 VAC, a sensor circuit in the Over/Undervoltage relay will cause K1 to denergize causing the Interior Main Prime Power Circuit Breaker CB1 contacts to open removing power from all units in the shelter. Also, a five (5) volt difference between any two phases will cause K1 to denerigize causing CB1 contacts to open removing power from the shelter.

Interior Main Prime Power Interrupt Circuit Breaker CB1: Next the AC Power comes to the Interior Main Prime Power Circuit Breaker. This circuit breaker is a 3-phase 60-amp circuit breaker. Power is then applied to all the other circuit breakers on the Power Distribution Panel Assembly. If voltage is removed from the coil of this circuit breaker it will cause this circuit breaker to open removing power from inside the shelter.

Circuit Breakers CB6 through CB9: These circuit breakers can be tripped if the coil is energized by the +28vdc that is applied through Thermal Switch S1 in the Road Side Air Duct Assembly (4A4) and Curb Side Air Duct Assembly (7A5). If the temperate reaches 150 degrees Fahrenheit the contacts in the Thermal Switch will close, applying +28vdc to the coils of these circuit breaker CB6 through CB9, causing these circuit breakers to open. The circuit breakers that are affected by this circuitry are; the DGM Group, DLED1/ 2, LVPS 1/ 2, and the Shelter Heater.

2-9

FIG 2-2a AN/TRC-170(V)3 POWER DISTRIBUTION PANEL ASSEMBLY

2-10

FIG 2-2b AN/TRC-170(V)3 POWER DISTRIBUTION PANEL ASSEMBLY

2-11

FIG 2-2c AN/TRC-170(V)3 POWER DISTRIBUTION PANEL ASSEMBLY

2-12

AN/TRC-170 (V)3 POWER DISTRIBUTION PANEL

AN/TRC-170(V)3 Power Distribution Panel, Controls, and Indicators

2-13 Item Indicator Description 1 INTERIOR MAIN - prime Applies prime input power to shelter equipment and power interrupt circuit provides overload protection. CB1 is a 3-phase 60-amp breaker breaker. 2 HPA – circuit breaker Applies prime power to the power amplifier and provides over load protection. CB2 is a 3-phase 30-amp breaker. 3 CONTROL CB TRIPPED - Indicates control circuit breaker is open. indicator lamp (red) 4 FREQUENCY METER A reed-type frequency meter that indicates 400 Hz line frequency. 5 PHASE SELECT - switch Selects phase A, B, or C of primary power to be monitored by meter. 6 VOLTS – meter Indicates the voltage of phase A, B, C of primary power. 7 LIGHT INTLK OVERRIDE In OVERRIDE position, the shelter interior lights remain - NORMAL switch on when door is opened. In NORMAL position, the shelter interior lights turn off when door is opened and red blackout light comes on. 8 DGM GROUP - circuit Applies prime power to LGM 1, GM, TGM, and LGM-2 breaker or LSCDM and provides overload protection. CB6 is a single-phase 10-amp breaker. 9 DLED ½ - circuit breaker Applies prime power to DLED 1 & 2 and provides overload protection. CB7 is a single-phase 2-amp breaker. 10 SHELTER HEATER – Applies prime power to shelter heaters and provides circuit breaker overload protection. CB9 is 3-phase 20-amp breaker. 11 INTR CNVC OUTLET – Applies prime power to convenience outlets in shelter and circuit breaker provides overload protection. CB12 is a single-phase 15- amp breaker. 12 FAN PWR CONV - circuit Applies prime power to AC-to-AC Converter and breaker provides overload protection. CB10 is 3-phase 10-amp breaker. 13 LVPS 1 / 2 circuit breaker Applies prime power and provides overload protection for both Low Voltage Power Supplies. CB8 is a 3-phase 10- amp breaker. 14 VENT FAN - circuit breaker Applies prime power and provides overload protection for the vent fan. CB5 is a single-phase 2-amp breaker. 15 LIGHTS – circuit breaker Applies prime power and provides overload protection for the shelter interior lights. CB4 is a single-phase 5-amp breaker. 16 AMPERES – meter Indicates the input current for each phase. 17 Frequency meter A reed-type frequency meter that indicates 50/60 Hz line frequency. AN/TRC-170(V)3 POWER UP PROCEDURES

Step Action Observation

2-14 1 On the Power Entry Panel outside the Prime power and ground connection is shelter make sure that the Main Power made. cable is connected to the Prime AC Power Connector J1 and the ground connection is made. 2 Ensure that all of the Air Exhaust and Air Exhaust and Air Inlet Panels are Air Inlet Panels are open. open. 3 On the Power Entry Panel open the Primary circuit breakers are in the OFF circuit breaker cover and ensure that all position. circuit breakers are in the OFF position. 4 Ensure that all circuit breakers on Power All circuit breakers on the Power Distribution Panel are in the OFF Distribution Panel are in the OFF position. position. 5 Turn on prime power at source. Note the Prime power is on. frequency (50, 60 or 400 Hz) of prime power. 6 On the Power Entry Panel, set On the Power Distribution Unit, CB EXTERIOR MAIN circuit breaker to TRIPPED indicator is off. ON. 7 Set the INTERIOR MAIN circuit Prime power is on. breaker to the ON position. NOTE If blackout condition exists, set LIGHT INTLK OVERRIDE switch to the NORMAL position. The white shelter lights will turn off when the shelter door is opened. 8 Set the Lights circuit breaker to the ON Lights circuit breaker is in the ON position. position. Ensure that each light switch is pulled out. The shelter lights go on. 9 Set the LIGHT INTLK OVERRIDE The shelter lights remain on when the switch to the OVERRIDE position. door is open. CAUTION Voltage of each phase must be within  5 Vac of each other. Do not continue if the voltage or frequency are out of tolerance as listed in steps 10 through 12. 10 Set the PHASE SELECT switch to  A. The Voltmeter indicates 120  12 Vac. The frequency meters indicates 55  7 or 400  20 Hz. 11 Set the PHASE SELECT switch to  B. Same as for  A, listed in step 10. 12 Set the PHASE SELECT switch to  C. Same as for  A, listed in step 10. 13 On the DGM Equipment set the Power ON-OFF switch to the ON position. 14 Set the DGM Group circuit breaker to DGM Equipment Power indicators are

2-15 ON. on. 15 Set the LVPS ½ circuit breaker to the LVPS Power indicator is on. ON position. SHELTER Hours Meter starts operating. A white marker will appear intermittently between the first two- meter digits indicating that the meter is operating. The meter will become stabilized within 30 seconds. 16 Set FAN PWR CONV circuit breaker to AC-to-AC converter INPUT Power the ON position. indicator is on. You will hear a high pitch noise from the 400-hertz fans that are running. 17 Make sure all air inlets and outlets are Normal airflow is present at all the open. outlets. 18 Set the HPA circuit breaker to the ON HPA circuit breaker is in the ON position. position. 19 If the Voice Orderwire Control unit alarms sounds, depress the SUPPR/TEST push-button. 20 If the FAULT-SUMMARY indicator on Indicator goes off. the Voice Orderwire Control unit is on, press the FAULT-RESET switch. 21 If the remaining circuit breakers the The circuit breakers are in the ON Vent Fan, DLED ½, Shelter Heater, and position. INTR ON Outlet are required to be on. Then proceed by turning them ON.

2-16

FO 2-3 AN/TRC-170(V)3 AC POWER DISTRIBITION BLOCK DIAGRAM

2-17

AN/TRC-170 SHELTER GROUNDING

GROUNDING: The TROPO system must be grounded in 4 places , however only 3 ground rods are needed.

(1). The generator or the power source (2) The shelter power entry panel (3) At both signal entry panels, each of which should have separate ground straps, but which may be connected to the same ground rod..

GROUND SYSTEM: A very important part of setting up the shelter is the installation of these grounds. Bad grounds are one of the most common causes of poor tactical communications. A suitable ground system is needed to provide personnel safety, equipment protection, and electrical noise reduction. A low resistance ground cable attached to the equipment provides personnel safety and equipment protection. Electrical noise reduction is accomplished on communications circuits by ensuring the resistance to earth ground is minimal between signal ground points throughout the communication facility. These ground points prevent noise sources within the van from radiating the noise to the communication circuits.

Some factors that may affect resistance in ground are temperature, amount of moisture in soil, mineral content, and topsoil thickness. The most common ways to improve a ground system is to use larger ground rods in diameter and length. Drive the ground rods deeper than usual.

2-18

Air Duct Thermal Switch Circuitry

Both of the AN/TRC-170(V)2 and the AN/TRC-170(V)3 systems Air Duct Assemblies utilize a Thermal Switch to detect temperature. The Thermal Switch S1 contacts close when the temperature reaches 150 degrees Fahrenheit, which allows +28vdc to be applied to the coils of Circuit Breakers CB6 through CB9. The +28vdc will then cause these circuit breakers to open. The circuit breakers that are affected by this circuitry are; the DGM Group, DLED1/ 2, LVPS 1/ 2, and the Shelter Heater. The temperature has to drop to 146 degrees before the Thermal Switch S1 contacts open again. This circuitry is designed to prevent damage to the equipment when the Air Duct Assembly temperate reaches 150 degrees Fahrenheit. The one Air Duct Assembly in the AN/TRC-170(V)2 is the 2A1 assembly. The two Air Duct Assemblies in the AN/TRC-170(V)3 are the Roadside 4A4 and Curbside 7A5 assemblies.

AIR DUCT THERMAL SWITCH CIRCUITRY

2-19

AC to AC CONVERTER

PURPOSE: The function of the AC-AC Converter is to convert 50, 60, and 400 Hz prime power to a 400 HZ, 255 volts 3-phase (quasi-square wave) for the purpose of driving the 400 Hertz fans in the Transmit Modem, Receive Modem, Upconverter, Shelter Rack, and the High Power Amplifier (Klystron and unit fans to include the FAINT, and the three Inverters). The AN/TRC-170(V)3 contains only one AC-to-AC Converter (7A4). The AN/TRC-170(V)2 contains two AC-to-AC Converters. The AC-to-AC Converter (6A7) only powers the fans in High Power Amplifier number 2. The AC-to-AC Converter (7A7) powers the fans in the High Power Amplifier number 1, Upconverters 1 and 2, Transmit Modem, Receive Modem, and Shelter Air Duct Assembly. In the AN/TRC-170(V)3 the AC-to-AC Converter powers all the equipment fans.

AC to AC CONVERTER SPECIFICATIONS

Input AC Power 115 VAC Frequency 50/60/400 Phase Three (3) Outputs AC Power 255 VAC Frequency 400 Hertz Phase Three (3)

Output Fault Monitor DC voltage logic signal as a Summary Fault. Signal This fault is displayed on the Alarm Monitor Unit as a LVPS fault.

2-20

SIGNAL FLOW for the AC-to-AC Converter – Refer to FO 2-1

(1). A3 Power Inverter Assembly: The 115 VAC 3-phase, 50/60/400 Hertz input power is first applied to the A3 Power Inverter Assembly. This 3-phase 115 VAC is applied to a 3-phase bridge rectifier circuit consisting of diodes CR1 through CR6. The +28 VDC input from the Low Voltage Power Supply (LVPS) is applied to a +24 VDC regulator on the A3 and then distributed throughout the AC-to-AC Converter.

(2). A2 Fault Detector Circuit Card: Receives the +24 VDC from the A3 Power Inverter Assembly and sends this voltage to the A1 Driver Circuit Card.

(3). A1 Driver Circuit Card: The +24 VDC from the A2 Fault Detector Circuit Card is applied to a +12 VDC regulator on the A1 Driver CCA. This +12 VDC is then applied to the start the Clock Generator circuitry. The three outputs of the clock generator circuitry is applied to the trigger timing circuitry, the output of the Trigger Timing circuitry is applied to the Trigger Driver circuitry. The three triggers A, B, and C outputs are then sent to the A3 Power Inverter Assembly. If the A2 Fault Detector CCA detects a fault, it sends a signal to the Trigger Inhibit gates, blocking the Timing Triggers from feeding the Trigger Driver circuitry.

(4). A3 Power Inverter Assembly: The Trigger Inputs A, B, and C are received from A1 Driver CCA. These Trigger inputs are used as inputs to the power transistors Q1 through Q6. The switching of these transistors generates the AC output at a frequency of 400 hertz. The output of these transistors is then sent to Transformer T2. Fuse F1 is mounted on this assembly and limits the amount of current that is drawn on the output voltages that power the fan assemblies within the TROPO system.

(5). T2 Transformer Assembly: The 255 Vac 3-phase 400 hertz output from the A3 Power Inverter Assembly is received by Transformer T2. This transformer is used to increase the current on the secondary output to the load. It also matches the impedance in order to transfer energy from the source to the load. The output of this transformer is then sent to output connectors J2 and J3. Also, samples of the three-phase output are then sent to the A2 Fault Detector Circuit Card.

(6). A2 Fault Detector Circuit Card: Receives the three sample Inverter outputs and analyzes that the output voltages are correct and present. If one or more of the output voltages are missing or low in amplitude, then a fault signal is generated. This fault signal will then illuminate LED DS2 the Output Fault on the front panel and the Summary Fault signal is sent to the Alarm Monitor Unit and displayed as a LVPS fault. It also monitors the +280VDC to ensure that an over voltage condition does not occur, if an over voltage condition occurs then an inhibit signal is sent to the A4 Resistor Step-Start Circuit Card.

(7). A4 Resistor Step-Start Circuit Card: If a fault is detected as an input from the A2 Fault Detector Circuit Card it then sends a signal to the A5 Resistor Step-Start Circuit Card causing the relays on the A5 CCA to open stopping current flow.

2-21 (8). A5 Resistor Step-Start Circuit Card: This CCA limits the current flow on the initial turn on. It also controls current flow through relays K1 and K2.

AC to AC Converter 255 VAC 3-Phase 400 HZ Output Distribution

PURPOSE: The function of the AC-AC Converter is to convert 50, 60, and 400 Hz prime power to a 400 HZ, 255 volts 3-phase (quasi-square wave) for the purpose of driving the 400 HZ fans in the Transmit Modem, Receive Modem, Upconverter, Shelter Rack, and the High Power Amplifier (Klystron and unit fans to include the FAINT, and the three Inverters). The AN/TRC-170(V)3 contains only one AC-to-AC Converter (7A4). The AN/TRC-170(V)2 contains two AC-to-AC Converters. The AC-to-AC Converter (6A7) only powers the fans in High Power Amplifier number 2. The AC-to-AC Converter (7A7) powers the fans in the High Power Amplifier number 1, Upconverters 1 and 2, Transmit Modem, Receive Modem, and Shelter Air Duct Assembly. In the AN/TRC-170(V)3 the AC-to-AC Converter powers all the equipment fans.

(1). In the AN/TRC-170(V)3 the AC to AC Converter (7A4) outputs are coupled to the RF Amplifier HPA (2A1) and also to the AC Distribution Panel Unit 13 where it is the distributed to the Upconveter (3A1), TROPO Transmit Modem (4A1), TROPO Receive Modem (4A2), Air Duct Assembly Curb Side (7A5), and the Air Duct Assembly Road Side (4A4). Refer to FIG 2-7.

2-22 255 VAC 3-PHASE TROPO TRANSMIT 400 HZ MODEM 4A1 255 VAC Contains one fan assy 3-PHASE AC AC to AC CONVERTER 400 HZ DISTRIBUTION PANEL 7A4 J2 255 VAC UNIT 13 3-PHASE 400 HZ TROPO RECEIVE MODEM 4A2 Contains one fan assy J3

255 VAC 3-PHASE 400 HZ 255 VAC AIR DUCT Curb Side 3-PHASE 7A5 400 HZ 255 VAC Contains two fans 3-PHASE 400 HZ RF AMPLIFIER HPA 2A1 * See Note UPCONVERTER AIR DUCT Road Side Contains six fans 3A1 4A4 Contains one fan assy 255 VAC Contains two fans 3-PHASE 400 HZ Note: The HPA has six fans: 1. HPA FAN 2. KLYSTRON FAN 3. FAINT ASSY 4. INVERTER A 5. INVERTER B 6. INVERTER C

FIG 2-7 AC-AC CONVERTER (255 VAC 3-PHASE 400 Hz) OUTPUT DISTRIBUTION FOR THE AN/TRC-170(V)3 EQUIPMENT FANS

2-23

AC-to-AC Converter Front Panel Indicators and Circuit Cards

Item Indicator Description 1 OUTPUT FAULT LED (red) Indicates an under voltage or over current condition. 2 INPUT POWER LED (green) Indicates the +28 vdc input is applied from the Low Voltage Power Supply.

2-24 3 208V ON LED (green) Indicates the 208V is present at the power supply on the A3 Power Inverter Assembly. 4 A1 Driver CCA Has three green LEDs that indicate that the trigger drive signal is present for each of the three output phases. Normal indication is that the LEDs are on. 5 A2 Fault Detector CCA Has one red LED which illuminates when any one of the internal circuits are faulty. AC-to-AC Converter A3 Power Inverter Module & Fuse F1 Location

2-25 Item Indicator Description 1 A3 Power Inverter Module Provides 255 VAC, 3-Phase 400 Hertz, Output Power for the TROPO fans. 2 Fuse, F1 Fuse, 15 amps for protection of the A3 Power Inverter Module. This Fuse, F1 is mounted on this module.

2-26

CHAPTER 3

PP-7904 & PP-7905 Low Voltage Power Supplies and DC Voltage Distribution Units

PP-7904

PP-7905

3-1 PURPOSE: The PP-7904 and PP-7905 Low Voltage Power Supplies (LVPS) provide the DC Voltages to all the units within the Tropo system excluding the (DGM) Equipment. The outputs from these two Low Voltage Power Supplies are coupled to DC distribution units bus bar and then distributed to various assemblies with the Tropo system. The PP-7904 is called LVPS - 1 and the PP- 7905 is called LVPS - 2. LVPS – 1 supplies only positive voltages and LVPS – 2 provides both negative and positive voltages.

PP-7904 LOW VOLTAGE POWER SUPPLY (LVPS - 1) SPECIFICATIONS

Input AC Power 115 VAC Frequency 50/60/400 Phase Three (3) Phase Outputs Voltage Current Regulation Over Voltage DC Volts + 5.3 VDC 22 Amps 2% + 6 vdc + 15 VDC 18 Amps 2% + 18 vdc + 28 VDC 8 Amps 2% + 32 vdc + 28 VDC 8 Amps 2% + 32 vdc Shut Down Protection If any internal Power CCA exceeds  5% of rated output. If the LVPS has an internal over temperature condition. If any overcurrent exist on any internal CCA voltages. The ganged main circuit breaker will trip, when shelter temperature reaches 150 degrees. Cooling Cooled by an internal fan using the internal +28 VDC (B) provided by the A3 CCA.

PP-7905 LOW VOLTAGE POWER SUPPLY (LVPS - 2) SPECIFICATIONS

Input AC Power 115 VAC Frequency 50/60/400 Phase Three (3) Phase Remote LVPS Disable Logic level 1 (high) is sent from the Transmit or Receive Tropo Modem if an over temperature condition is present in either one of these units. Outputs Voltage Current Regulation Over Voltage DC Volts - 5.3 VDC 22 Amps 2% - 6 vdc + 5.3 VDC 22 Amps 2% + 6 vdc - 15 VDC 18 Amps 2% - 18 vdc + 28 VDC 8 Amps 2% + 32 vdc Shut Down Protection If any internal Power CCA exceeds  5% of rated output. If the LVPS has an internal over temperature condition. If any overcurrent exist on any internal CCA voltages. If an over temperature exist in the Transmit or Receive Tropo Modem. The ganged main circuit breaker will trip, when shelter temperature reaches 150 degrees. Cooling Cooled by an internal fan using the internal +28 VDC (C) provided by the A3 CCA.

SIGNAL FLOW for PP-7904 Low Voltage Power Supply (LVPS - 1) - Refer to FO 3-1

3-2

(1) The PP-7904 Low Voltage Power Supply (LVPS - 1) operates on 115 VAC 3-phase, 50/60/400 Hertz input power. The 3-phase input AC is first applied to the EMI Filter FL1, which reduces emissions on the input lines. Neon light indicator DS7 located under the top cover on back left side will illuminate when Phase A and Neutral are correctly passed through the EMI Filter FL1. The output of the EMI Filter FL1 is coupled to a bridge rectifier circuit CR1 and auxiliary power supply Transformer T1 circuitry. If the input power rises to 145 VAC, the Equipment Failure indicator lights and the power supply shuts down. The power supply is protected against damage caused by overvoltage, overcurrent, and overheating. If the power supply-cooling fan fails to properly cool the power supply, the Equipment Failure indicator lights and the power supply output shuts down. In the AN/TRC-170(V)2 the PP-7904 is located on the Roadside and in the AN/TRC-170(V)3 the PP-7904 is located on the Curbside.

(2) The filtered 3-phase 115 VAC is applied to a 3-phase bridge rectifier circuit CR1 and auxiliary power supply Transformer T1 circuits. The bridge rectifier circuit CR1 produces the unregulated +/- 150 VDC and the step down transformer T1 and associated circuitry produces the unregulated + 20 VDC, respectively. These two DC voltages are applied to the four power circuit cards. Each power circuit card develops a regulated dc voltage. DS1 the Power On LED, located on the front panel is illuminated when the +20 VDC is properly developed by step down Transformer T1 and associated circuitry. If the output voltage of a power circuit card exceeds  5 % of the rated output, the Equipment Failure lights and the power supply output shuts down. Also, whenever the Equipment Failure indicator lights, an LVPS signal is applied to the Alarm Monitor to light the LVPS fault indicator. In each of these cases, if the fault condition passes, the power supply is automatically reset. If there is an Overcurrent condition, a front panel Overcurrent indicator lights and the current for this power circuit card is reduced. If the Overcurrent condition passes, the power circuit card output is automatically returned to normal operation. The output of each power circuit card can be adjusted by variable resistor R20 located on the card and monitored at the front panel test points.

(3) A1 +5.3 VDC Power Circuit Card: Receives the +/- 150 VDC and + 20VDC input voltages from the bridge rectifier circuitry CR1 and Transformer T1. It then produces a filtered and regulated voltage that appears on TB-1 as the +5.3 VDC (A) output. The output of this +5.3 VDC power circuit card card can be adjusted by variable resistor R20 located on this circuit card and monitored at the front panel test TP-3 and TP-4. The output voltage is adjusted for a range of +5.25 to +5.35 VDC.

(4) A2 +28 VDC Power Circuit Card: Receives the +/- 150 VDC and + 20VDC input voltages from the bridge rectifier circuitry CR1 and Transformer T1. It then produces a filtered and regulated voltage that appears on TB-1 as the +28 VDC (A) output. The output of this + 28 VDC power circuit card can be adjusted by variable resistor R20 located on this circuit card and monitored at the front panel test points TP-2 and TP-1. The output voltage is adjusted for a range of +27.72 to +28.28 VDC.

3-3 + 28 VDC that powers the internal Fan Assembly B1, for this (LVPS - 1). The output of this + 28 VDC power circuit card can be adjusted by variable resistor R20 located on this circuit card and monitored at the front panel test points TP-8 and TP-7. The output voltage is adjusted for a range of +27.72 to +28.28 VDC.

(6) A4 +15 VDC Power Circuit Card: Receives the +/- 150 VDC and + 20VDC input voltages from the bridge rectifier circuitry CR1 and Transformer T1. It then produces a filtered and regulated voltage that appears on TB-2 as the +15 VDC output. The output of this + 15 VDC power circuit card can be adjusted by variable resistor R20 located on this circuit card and monitored at the front panel test points TP-6 and TP-5. The output voltage is adjusted for a range of +14.85 to +15.15 VDC.

SIGNAL FLOW for PP-7905 Low Voltage Power Supply (LVPS - 2) - Refer to FO 3-2

(1) The Low Voltage Power Supply (LVPS - 2) operates on 115 VAC 3-phase, 50/60/400 Hertz input power. The 3-phase input AC is first applied to the EMI Filter FL1, which reduces emissions on the input lines. Neon light indicator DS7 located under the top cover on back left side will illuminate when Phase A and Neutral are correctly passed through the EMI Filter FL1. The output of the EMI Filter FL1 is coupled to a bridge rectifier circuit CR1 and auxiliary power supply Transformer T1 circuitry. If the input power rises to 145 VAC, the Equipment Failure indicator lights and the power supply shuts down. This Low Voltage Power Supply (LVPS # 2) has a remote disable logic level 1 (high) signal from the Tropo Transmit or Receive Modem that causes the power supply to shut down if heat problems occur in either of the modem assemblies. The power supply is protected against damage caused by overvoltage, overcurrent, and overheating. If the power supply- cooling fan fails to properly cool the power supply, the Equipment Failure indicator lights and the power supply output shuts down. Note that Low Voltage Power Supply (LVPS-2) has both negative and positive voltages. The PP-7905 is located on the Roadside for both the AN/TRC-170(V)2 and AN/TRC-170(V)3 systems.

(2) The filtered 3-phase 115 VAC is applied to a bridge rectifier circuit CR1 and auxiliary power supply Transformer T1 circuits. The bridge rectifier circuit produces the unregulated +/- 150 VDC, and the step down transformer T1 and associated circuitry produces the unregulated + 20 VDC, respectively. These two DC voltages are applied to the four power circuit cards. Each power circuit card develops a regulated dc voltage. DS1, the Power On LED located on the front panel, is illuminated when the +20 VDC is properly developed by step down Transformer T1 and associated circuitry. If the output voltage of a power circuit card exceeds  5 % of the rated output, the Equipment Failure lights and the power supply output shuts down. Also, whenever the Equipment Failure indicator lights, an LVPS signal is applied to the Alarm Monitor to light the LVPS fault indicator. In each of these cases, if the fault condition passes, the power supply is automatically reset. If there is an Overcurrent condition, a front panel Overcurrent indicator lights and the current for this power circuit card is reduced. If the Overcurrent condition passes, the power circuit card output is automatically returned to normal operation. The output of each power circuit card can be adjusted by variable resistor R20 located on the circuit card and monitored at the front panel test points.

3-4 (3) A1 +5.3 VDC Power Circuit Card: Receives the +/- 150 VDC and + 20VDC input voltages from the bridge rectifier circuitry CR1 and Transformer T1. It then produces a filtered and regulated voltage that appears on TB-1 as the +5.3 VDC (B) output. The output of this + 5.3 VDC power circuit card can be adjusted by variable resistor R20 located on this circuit card and monitored at the front panel test points TP-3 and TP-4. The output voltage is adjusted for a range of +5.25 to +5.35 VDC.

(4) A2 – 5.3 VDC Power Circuit Card: Receives the +/- 150 VDC and + 20VDC input voltages from the bridge rectifier circuitry CR1 and Transformer T1. It then produces a filtered and regulated voltage that appears on TB-1 as the –5.3 VDC output. The output of this -5.3 VDC power circuit card can be adjusted by variable resistor R20 located on this circuit card and monitored at the front panel test points TP-2 and TP-1. The output voltage is adjusted for a range of -5.25 to -5.35 VDC.

(5) A3 +28 VDC Power Circuit Card: Receives the +/- 150 VDC and + 20VDC input voltages from the bridge rectifier circuitry CR1 and Transformer T1. It then produces a filtered and regulated voltage that appears on TB-2 as the +28 VDC (C) output. This A3 power circuit card provides the + 28 VDC that powers the internal Fan Assembly B1, for this (LVPS – 2). The output of this + 28 VDC power circuit card can be adjusted by variable resistor R20 located on this circuit card and monitored at the front panel test points TP-8 and TP-7. The output voltage is adjusted for a range of +27.72 to +28.28 VDC.

(6) A4 -15 VDC Power Circuit Card: Receives the +/- 150 VDC and + 20VDC input voltages from the bridge rectifier circuitry CR1 and Transformer T1. It then produces a filtered and regulated voltage that appears on TB-2 as the -15 VDC output. The output of this -15 VDC power circuit card can be adjusted by variable resistor R20 located on this circuit card and monitored at the front panel test points TP-6 and TP-5. The output voltage is adjusted for a range of -14.85 to –15.15 VDC.

3-5 PP-7904 Low Voltage Power Supply (LVPS-1) Indicators

Item Indicator Description 1 POWER ON LED (green) Illumi nates when Transformer T1 and associated circuitry produce the +20 VDC for LVPS-1. 2 EQUIPMENT FAILURE LED (red) Illuminates when the output voltages are not within 5 % of nominal values. 3 OVERCURRENT +28V LED (red) Illuminates when the +28V (B) overcurrent is exceeded. The two test points above are refereed to as TP7 and TP8 as shown on FO 3-1. 4 OVERCURRENT +15V LED (red) Illuminates when the +15V overcurrent is exceeded. . The two test points above are refereed to as TP5 and TP6 as shown on FO 3-1. 5 OVERCURRENT +5.3V LED (red) Illuminates when the +5.3V (A) overcurrent is exceeded. The two test points above are refereed to as TP3 and TP4 as shown on FO 3-1. 6 OVERCURRENT +28V LED (red) Illuminates when the +28V (A) overcurrent is exceeded. The two test points above are refereed to as TP1 and TP2 as shown on FO 3-1.

3-6 PP-7905 Low Voltage Power Supply (LVPS-2) Indicators Note that LVPS-2 has both negative and positive voltages

Item Indicator Description 1 POWER ON LED (green) Illuminates when Transformer T1 and associated circuitry produce the +20 VDC for LVPS-2. 2 EQUIPMENT FAILURE LED (red) Illuminates when the output voltages are not within 5 % of nominal values. 3 OVERCURRENT +28V LED (red) Illuminates when the +28V (C) overcurrent is exceeded. The two test points above are refereed to as TP7 and TP8 as shown on FO 3-2. 4 OVERCURRENT –15V LED (red) Illuminates when the –15V overcurrent is exceeded. The two test points above are refereed to as TP5 and TP6 as shown on FO 3-2. 5 OVERCURRENT +5.3V LED (red) Illuminates when the +5.3V (B) overcurrent is exceeded. The two test points above are refereed to as TP3 and TP4 as shown on FO 3-2. 6 OVERCURRENT –5.3V LED (red) Illuminates when the –5.3V overcurrent is exceeded. The two test points above are refereed to as TP1 and TP2 as shown on FO 3-2.

3-7 PP-7904 Low Voltage Power Supply (LVPS-1) Circuit Card Locations

LVPS-1 Curbside in (V)3

3-8 PP-7905 Low Voltage Power Supply (LVPS-2) Circuit Card Locations

LVPS-2 (Roadside in (V)3

3-9 PP-7904 Low Voltage Power Supply (LVPS-1) Rear Panel

Connector Jack Description J1 Power 3-Phase VAC Input J2 Alarm Monitor Output TB-1 +5.3 VDC (A) and +28 VDC (A) Output TB-2 +28 VDC (B) and +15 VDC Output E1-GND Ground Connection

PP-7905 Low Voltage Power Supply (LVPS-2) Rear Panel

Connector Jack Description J1 Power 3-Phase VAC Input J2 Alarm Monitor Output and Remote LVPS-2 Shutdown from Tropo Transmit or Receive Modem as an input logic level (1) voltage. TB-1 +5.3 VDC (B) and –5.3 VDC Output TB-2 +28 VDC (C) and -15 VDC Output E1-GND Ground Connection

3-10 PP-7904 and PP-7905 LVPS DS7 Neon Light Location

CCA Variable Resistor R20 and LED Locations

3-11 DC Voltage Distribution

PURPOSE: The two Low Voltage Power Supplies in the AN/TRC-170(V)3 are coupled to the DC Distribution Units 14 and 15. These DC Voltages are then distributed to various assemblies within the Tropo system. These DC Voltages are not coupled to the Digital Group Multiplexer (DGM) Equipment.

(3) In the AN/TRC-170(V)3 the PP-7904 Low Voltage Power Supply (LVPS - 1) outputs are coupled to the DC Distribution Unit # 14. Please refer to Figure FO 3-5.

(4) In the AN/TRC-170(V)3 the PP-7905 Low Voltage Power Supply (LVPS - 2) outputs are coupled to the DC Distribution Unit # 15. Please refer to Figure FO 3-6.

3-12 AN/TRC-170 (V3) Low Voltage Power Supply 7904 & PP-7905 Troubleshooting and Alignment- PURPOSE:

The Low Voltage Power Supplies (LVPS) PP-7904 (LVPS 1) and PP-7905 (LVPS 2) provide the DC Voltages to all the units within the Tropo system excluding the (DGM) Equipment. The outputs from these two Low Voltage Power Supplies are coupled to DC distribution units bus bar and then distributed to various assemblies with the Tropo system. The PP- 7904 is called LVPS - 1 and the PP-7905 is called LVPS - 2. LVPS – 1 supplies only positive voltages and LVPS – 2 provides both negative and positive voltages. PURPOSE:

PP-7904 LVPS 1 PP-7904 Specifications

LVPS 1 is located towards the bulk-head of the shelter and is curbside.

 It contains four CCA power supplies for various shelter components. Most importantly is the AC-AC Converter.  It only provides Positive voltages, however; the +5.3 and +15 VDC CCAs are interchangeable with the -5.3VDC and -15VDC CCAs in LVPS 2. PURPOSE:

PP-7905 LVPS 2 PP-7905 Specifications

LVPS 2 is located towards the bulk-head of the shelter and is roadside.

 It contains four CCA power supplies for various shelter components.  It provides both Negative and Positive voltages, however; the -5.3 and the -15 VDC CCAs are interchangeable with the +5.3VDC and +15 VDC CCAs in LVPS 1. Equipment description:

PP-7905 LVPS 1 Equipment description:

PP-7905 LVPS 2 Equipment description:

PP-7904 LVPS-1 (Curbside) Circuit Card Location

C1 & C2 Equipment description:

PP-7905 LVPS-2 (Roadside) Circuit Card Location

C1 & C2 Equipment description:

PP-7905 LVPS-1 (Curbside) Rear panel Equipment description:

PP-7905 LVPS-2 (Roadside) Rear panel Equipment description:

PP-7904 and 7905 LVPS DS7 Neon Light Location Equipment description:

CCA Variable Resistor R20 and LED Locations Unit 3 – Operations Student Handout Operations PC, Initial Turn On Procedure

If an unsafe procedure is spotted, stop the procedure immediately.

Shelter Turn On Procedure NOTE: Follow these steps in order. 1. Shelter Ground Connection: Verify that the appropriate ground connected to power entry panel. 2. Primary Power Source: Verify that this is connected to shelter but not turned ON. 3. Verify that the Shelter Air Vents opened. 4. Verify that the Exterior Circuit Breakers (CB) is OFF. 5. Verify that the Interior Power Distribution Panel CB’s is OFF. 6. Verify that the Rack Mounted Power Switches are OFF. 7. Verify that the Primary Power Source is ON. NOTE: Turn on the generator and use the frequency meter (in the shelter) to check the output frequency at the generator. The Frequency, should be 60 Hz plus/minus 2 HZ. 8. Turn on Interior Main CB. Turn Exterior Main ON only if Deicer is needed. NOTE: The Exterior Main CB is on the Exterior power distribution panel and the Interior Main is on the inside of the shelter, on the Main Power Distribution Panel. Light CB ON: Interior lights will come on now if Interlock Switch is already in the over ride position and the Light Fixture On/Off switches are ON. If the lights do not come on, continue to the next step. If the lights come on, skip the next step. The Light Interlock Override switch is set to OVERRIDE: Interior lights should be on now. If not, check the On/Off toggle switch on the light fixtures. 9. Turn on CS6716, LVPS and AC-AC Inverter NOTE: Move LVPS Breaker up to mid position and listen for a tone; then rotate all the way up. DO NOT continue if LVPS has faults. No other breakers need to be turned on at this point. The outlet and and lights can be turned on. DO NOT turn on the heater

10. Voltage and Frequency Check instructions CAUTION! The voltage of each phase must agree within ±-5 VAC. Do not continue if the voltage or frequency is out of tolerance. Frequency of each phase must be 55 ± 7 Hz on the frequency meter.

2900 Titan Row, Suite 142 Orlando, FL 32809 (407) 854-1950 Sheet 1 of 1

CHAPTER 5

Terminal Signal Flow

4-1 The AN/TRC-170(V)3 has two Signal Entry Panels (SEP). The signal entry panels are the way we interface with the local subscribers. The SEP in both versions of the terminals are identical. However they are in different locations.

Below we see the curbside view of the AN/TRC-170(V)3 S-250 shelter.

Signal Entry Panel #2 Signal Entry Panel #1

4-2 SIGNAL ENTRY PANEL 1

CX-11230 Coaxial cable input to GM-1 on the MD-1026. To the right of it GM-1 the associated surge protector assembly is labeled GM-1. The data format of this type of signal will be Conditioned Di-Phase. CX-11230 Coaxial cable input to GM-2 on the MD-1026. To the right of it GM-2 the associated surge protector assembly is labeled GM-2. The data format of this type of signal will be Conditioned Di-Phase. A 26 pair cable input to LGM-1. This connector can handle up to 13, 4-wire LGM-1 digital or analog subscribers. These 16 sets of binding post are inputs to LGM-1. The binding posts allows subscribers to connect directly to the terminal. Using the binding post allows access to all 16 channels available in the LGM. The 26 pair CH 1 – CH 16 cable input can be used in conjunction with the binding posts to access all 16 channels. Each binding post assembly can be removed to access the surge suppressors mounted on the rear of the assembly.

4-3 SIGNAL ENTRY PANEL 2

CX-11230 Coaxial cable input to GM-3 on the MD-1026. To the right of it GM-3 the associated surge protector assembly is labeled GM-3. The data format of this type of signal will be Conditioned Di-Phase. CX-11230 Coaxial cable input to GM-4 on the MD-1026. To the right of it GM-4 the associated surge protector assembly is labeled GM-4. The data format /LSCDM of this type of signal will be Conditioned Di-Phase. NOTE: The surge protector must be changed if the LSCD is used. A 26 pair cable input to LGM-1. This connector can handle up to 13, 4-wire LGM-2 digital or analog subscribers. These 16 sets of binding post are inputs to LGM-1. The binding posts allows subscribers to connect directly to the terminal. Using the binding post allows access to all 16 channels available in the LGM. The 26 pair CH 1 – CH 16 cable input can be used in conjunction with the binding posts to access all 16 channels. Each binding post assembly can be removed to access the surge suppressors mounted on the rear of the assembly. An additional two sets of binding post are provided for connection of the ROCU Remote Orderwire Control Unit (ROCU)

4-4

Signal Flow through AN/TRC-170(V)3 FO 5-2

Multiplexer TD-1235 (LGM) 6A2, 6A5. The Loop Group Multiplexer multiplexes up to 16 four wire, 16 or 32 KB/s conditioned diphase digital, or 16 voice frequency analog inputs on the line side into one balanced NRZ digital group on the equipment side. There are two LGMs mounted in the AN/TRC-170. LGM #1 is designated 6A2 and LGM #2 is 6A5.

Digital data Modem MD-1026 (GM) 6A3. The main purpose of the GM is to change the cable format to a balanced NRZ signal and vice versa. When used in the AN/TRC-170, the GM interfaces up to four groups of Conditioned Diphase, Bipolar, Dipulse signals or a mixture of the three. Conditioned Diphase is the most commonly used format. The operating mode is selected by installing the appropriate plug-in CCAs in the modem. In addition to mission traffic, each individual group of the diphase GM interfaces a 2 KB/s data orderwire (DOW) and a 16 KB/s digital voice orderwire (DVOW) or an analog voice orderwire (AVOW

Cable Driver Modem TD-1023 (LSCDM) 6A5. The Low Speed Cable Driver Modem (LSCDM) interfaces a repeated CX-11230 coax cable system on the cable side with the AN/TRC-170 system on the equipment side. The cable side input/output is a conditioned diphase signal group that is transmitted up to 40 miles via repeatered cable. The transmission range without repeaters is 1 mile. The LSCDM changes the cable input to NRZ for use by the AN/TRC-170. The LSCDM interfaces analog voice, digital voice, and digital data orderwires and supplies power feed to the cable repeaters (TD-1218 Low Speed Pulse Restorers (LSPRs)). The LSCDM accepts 1 NRZ format group of 72 to 2048 KB/s on the equipment side and transmits 1 group on the cable side (CDI) at 2304 KB/s. This is an optional piece of equipment, which is seldom if ever used. In the AN/TRC-170, the LSCDM is physically substituted for LGM 2, but electrically replaces GM Group 4.

Multiplexer TD-1236 (TGM) 6A4. The Trunk Group Multiplexer (TGM) multiplexes up to 4 data groups into 1 supergroup. It demultiplexes a supergroup into four separate groups at their original data rates. The TGM is capable of controlling a TSEC/KG-94A Trunk Encryption Device (TED) on both the group and supergroup side. Group data rates are from 72 to 2304 KB/s. Supergroup data rates are from 128 to 4608 KB/s.

Trunk Encryption Device TSEC/KG-94A (TED). The TED performs full encryption/decryption of group or supergroup mission traffic. One or two TEDs are used, as required. TED 1 (5A1A1) is used on the radio (supergroup) side while TED 2 (5A1A2) is used on the cable (group) side.

Dedicated Loop Encryption Device TSEC/KG-84 (DLED). The DLED encrypts/decrypts telemetry data that is processed through the CSCE function of the alarm monitor. DLED 1 (5A2A1) is used on the cable side. DLED 2 (5A2A2) is used on the radio side. The DLEDs are not used in the Army versions of the terminals.

VINSON TSEC/KY-58 7A3A1. This device encrypts/decrypts digital voice orderwire traffic originating and terminating at the voice orderwire control unit. It must be installed in the shelter because it is also used to change the analog of the headset to digital signal required by the radio.

4-5

Baseband Patch Panel 6A1. The Baseband patch Panel is used to interface the DGM gear with the Tropo Modem. The DLED Patch Panel interfaces the DOW with the Alarm Monitor panel.

DLED Patch Panel 7A1. The DLED patch panel provides for patching the local telemetry signals (DOW) to the radio and/or cable side of the AN/TRC-170. DLEDs can be included or omitted as appropriate. The DLED patch panel also provides a jack & associated lght for monitoring baseband and DLED patch panel activity.

IF Test Panel 5A4. The IF Test Panel contains a loop back circuit and an antenna alinement circuit. The loop back circuit provides a calibrated means of applying the Tropo Modem modulator IF output to any one or any combination of Tropo Modem demodulator inputs. The antenna alinement circuit converts the level of an IF signal to a DC voltage level proportional to the log of any of four IF signal levels. The IF Test Panel is an integral part of the signal flow. The V2 and V3/V5 models are not interchangeable.

Demodulator-Modulator Group OM-71 (Tropo Modem). The Tropo Modem contains circuitry by which digital data modulates a nominal 70 MHz IF at the transmit end (modulator) and recovers data from a nominal 70 MHz IF at the receiver (demodulator). The Tropo Modem processes mission traffic at data rates of 128 through 4096 KB/s. The are two separate components to the Tropo Modem. The first section is called the Modulator 4A1 section.

Electrical Frequency Synthesizer SN-53/AN/TRC-170. The synthesizer provides stable outputs in the 4.47 to 5.07 GHz ranges. These outputs supply local oscillator signals to the Up Converters and Down Converters. The synthesizer is phased locked to the 10 MHz signal from the Tropo Modem. The V3 contains one synthesizer 3A2, which provides a local oscillator frequency to one Up Converter and two Down Converters.

Transmitter Amplifier-Converter AM-7027 (Up Converter). The Up Converter is part of the transmitter subsystem. The Up Converter mixes the nominal 70 MHz IF with 4.47 to 5.07 GHz from the Synthesizer to produce the 4.4 to 5.0 GHz output signal. The V3 has one Up Converter designated 3A1, which drives the High Power Amplifiers.

RF Amplifier (HPA) 2A1. The HPA consists of two major subassemblies: Klytrson and High Voltage Power Supply. The klystron is a 5 cavity, continuous wave, 2 kW, air cooled amplifier. It operates in the 4.4 to 5.0 GHz band. The klystron and High Voltage Power Supply is not used when operating in the LOS mode.

Waveguide Entry Panels. The waveguide panels are located on either side of the door on the shelter. Here we connect the de-icer cables, waveguides, the W-100 cable used with the Remote Antenna Alignment Meter (RAAM) and the noise generator. On the V3 these are designated Units 12 & 13.

4-6

Antenna Entry Panel #1 Antenna Entry Panel #2

Antenna OE-354/TRC-170. The Quick Reaction Antenna (QRA) for the V3 uses two 6-foot diameter, linearly dual-polarized antennas which are mounted on a single boom. The rated gain of each antenna is 36.5 dB. These antennas are fed by flexible waveguide and are mounted on a crank- up support, which is part of the M116A trailer chassis. For operation, the antenna assembly is elevated to 12 feet. The two antennas and mounting boom are disassembled form the support and stored in the trailer for transport. Included with the antenna system are azimuth and elevation sensors and position indicators, as well as 3 flexible waveguides.

Receiver Amplifier Converter AM-7026 (Down Converter). The Down Converters are part of the receiving subsystem. The Down Converters provide preselection, amplification and postselection of the received microwave signal. The Down Converters contain a low noise amplifier (LNA) and a mixer which combines the 4.4 to 5.0 GHz received signal with a 4.47 to 5.07 GHz signal from the Synthesizer to produce the 70 MHz IF. One Down Converter (D/C) with each of the two antennas, this achieves space diversity reception. D/C # 1 is designated 3A3A2 with D/C #3 as 3A3A3. There is no D/C #2 present.

Demodulator 4A2. The demodulator performs the inverse function of the modulator. Specifically, it recovers the baseband data from the 4 receiver IF inputs.

Alarm Monitor BZ-250 (CSCE) 7A2. Equipment status information and performance data from all major components, including individual DGM and COMSEC units, are reported to the centralized alarm monitor. Here it is sampled, processed and evaluated and a determination of overall system performance is made. The resulting overall system performance assessment, as well as summaries of individual equipment status, is presented locally and is also formatted into a standard ASCII equipment status and performance telemetry message. The alarm monitor multiplexes this message into a 2 kb/s data orderwire (DOW). The DOW is not used in the Army systems.

4-7 Orderwire Control Unit C-10602 (VOCU) 7A3. The Voice Orderwire Control Unit (VOCU) provides a means of interfacing a VINSON, KY-58 secure voice instrument, with the 16 kB/s Digital Voice Orderwire. The connection is made on first come first served party line basis.

Remote Orderwire Control Unit (ROCU). The ROCU accesses the digital voice orderwire through the VOCU in the AN/TRC-170 shelter. The ROCU does not provide secure voice transmission to the VOCU. The ROCU is connected to the shelter by up to ¼ mile of WF-16 (field wire). The ROCU is also used to monitor the status of the van and provide visual and audible alarms if the status changes.

Analog Voice Orderwire (AVOW) 8A1. The AVOW provides an unencrypted, duplex voice interface with analog voice orderwire channels of the GM and the LSCDM. The AVOW does not connect to the radio side of the AN/TRC-170 terminal. It is also called the maintenance orderwire.

AN/TRC-170(V)3 Roadside Rack

4-8

AN/TRC-170(V)3 Curbside Rack

4-9 4.4 - 5.0 GHz 5A2A4 3A1 4.4 - 5.0 GHz 2A1 +60 dBm tropo +24 dBm tropo +27 dBm LOS 6A2 70 MHz @ 0 dBm +27 dBm LOS 1

16 Channels 128 - 576 KB/s e Horizontal U/C 1 HPA 1 n a

LGM 1 P

1 y Vertical

Terminal Interface 5A2A5 tr

1 odem n

CDI 1 thru 4 /G E

n 678 M W S

U C

(CX 11230) O X

U z H

1 DVOW 16 KB/s to OCU FO 1 thru 4 M 5A2A4

# 2

6A3 07 G

l (CX 11295) DNE Vertical anel e 5. o 72 - 4608 KB/s d P

n o y Horizontal r m t

GM 1 47 t e n 4.

P E

DOW 2 KB/s G /

y 678 D

r W S t 5A1A2 C 10 MHz 4.47 to 5.07 GHz LO t o DC #1 n 3A2 Reference

E TED

l Synthesizer 4.47 to 5.07 GHz LO t o DC #3 a 2 From DAR X 4 n DVOW 16 KB/s to OCU Modem

i 6A3 8

128 - 2304 KB/s 7 72 - 4608 KB/s 6A4 6 CS GM 2 l 128 - 2304 KB/s e n DOW 2 KB/s TGM a 128 - 1152 KB/s P h c

128 - 1152 KB/s O Test Signal

DI 70 MHz @ -23 dBm

2 Pat X 4 RA Only with DAR

e AT2

2A Modem

n 0 - 49 dB

a OW from GM-1 7A3 5A

OW from GM-2 X 4 OCU 6A5 h OW from GM-3

c R

16 Channels 128-576 KB/s DA a OW from GM-4 16 KB/s DVOW

LGM 2 P or LSCDM / 5A1A1 Receive BBPP 7A3A1 TED 4A1 Signal d 3A3A2 Tropo 4.4 to 5.0 n KY-58 GHz a 1 Modem b D/C 1

e 2 DVOW 16 KB/s to OCU s SUPERGROUP

6A3 a 128 - 4608 KB/s it 1

B n

72 - 4608 KB/s 8A1 DVOW 16 KB/s M GM 3 DOW 2 KB/s ounti DOW 2 KB/s AVOW r 5A3

(VinsVINSon)ON o n ng P o at i anel #2 U ct

7A1 e

7A1 odul S y P DVOW 16 KB/s M anel tr 6A3 Level Level n Conv Conv 72 - 4608 KB/s 3A3A3 GM 4 4A2 Receive Signal 4.4 to 5.0 GHz DOW 2 KB/s gnal E i

M D/C 3 p u G o S T r

G to n r per tu u

DVOW 16 KB/s 5A2A1 5A2A2 e S 6A5 R 72 - 4608 KB/s DLED 1 DLED 2 IF LSCDM r Test o t n

DOW 2 KB/s a

o Panel 7A2 i ct odul e 5A4 m S e

CESE D Note: The LSDCM is optional. It phyiscally replaces LGM 2 AN/TRC-170(V)3 (6A5) and electrically replaces GM4 Up Date: 16 SEP 07 Block Diagram FO 5-2.1

CHAPTER 11

IF TEST PANEL

11-1 IF TEST PANEL

The purpose of the Intermediate Frequency Test Panel (IFTP) is to provide a means of testing and measuring the performance of the Transmit and Receive sections of the TROPO Modem at the 70 Mhz IF level without using the Radio Frequency components. It also generates the Receive Signal Level (RSL) voltage to send to the monitor meter in the Alarm Monitor.

Fig. 11-1

The transmit Tropo Modem provides three (3) modulated 70 Mhz outputs (Fig 11-1). Two (2) of the outputs are sent to the Up Converters for signal processing. See also FO 11-1 and -2.

The third output is sent to the IF test panel for loopback testing. Not shown on the diagram above is a BNC connector on the front panel of the IF test panel where the transmitted 70 Mhz IF can be observed with the appropriate TMDE; i.e., Frequency Counter, Spectrum Analyzer or oscilloscope. Variable attenuators are placed in the transmit test signal path to allow level control of the test signal.

The four receive signals (two receive signals in the V3) from the Down Converters pass through the IF test panel and go on to each of the four receiver inputs of the Tropo Modem demodulator .

Four loop back switches are provided on the IFTP front panel (one for each receive path) whereby a sample of the transmitted signal can be injected into any one or all of the Receive Tropo Modem paths. By increasing the attenuation, thus decreasing the signal level being applied to the Tropo Modem Demodulator, we can simulate a weak receive signal and by comparison, determine to some extent the relative capabilities of each of the four demodulator channels.

Note: The I.F. loop back testing should only be done when there is no signal being received by the receivers. Any received signal will mix with the test signal and invalidate the BER reading.

Also note that any switch in loopback causes a Configuration Fault on the Alarm Monitor.

11-2 IF TEST PANEL SWITCHES AND INDICATORS

Fig 11-2

1 TEST SIGNAL - Allows monitoring of the 70 Mhz I.F. test signal from the transmit TROPO Modem (-23 dB)

2 40 dB variable Attenuator, attenuates the test signal in 10 dB steps

3 9 dB variable Attenuator, attenuates the test signal in 1 dB steps

4-7 Loop Back toggle switches in the NORM position allows normal operation of the respective receiver to pass through to the receive TROPO Modem. In the LB position injects the sample test signal from the TX TROPO Modem and also causes a Configuration Fault on the Alarm Monitor.

8 Loop Back LED - Lights if any LB switch is in Loop Back.

11-3 I.F. TEST PANEL REAR VIEW (CONNECTORS)

The V3 (Fig 11-4, below) will not have J12 through J15 and instead will have a J16 and J17. J16 and J17 are inputs to power splitters.

Fig 11-4

J16 takes the input from RX-1 and splits the signal for RX-1 and RX-2 signal paths to the Tropo Modem Demodulator. J17 takes the input from RX-3 and splits the signal for RX-3 and RX-4 signal paths to the Tropo Modem Demodulator. This is why the I.F. test panel is not interchangeable between V2 & V3.

J11 is for the test signal input from the Tropo Modem transmit section. This is fed through to a front panel BNC connector labeled Test Signal. It is also fed to the front panel loopback switches to provide loopbacks to the Tropo Modem Demodulator section as described above, and explained in more detail below.

IF Loopback Testing

The IF Loopback Testing function is provided to check the operation of the Tropo Modem Modulator and Tropo Modem Demodulator. Since the Tropo Modem BER reading is determined solely by examining the Tropo Modem framing pulses being received, a loopback sample of the signal being transmitted will cause the Tropo Modem to frame up on its own signal.

A sample of the modulated 70 MHz IF signal, labeled (TX IF TEST) from the Waveshaping CCA A7 within the Tropo Modem Modulator is coupled to the Tropo Modem Demodulator via the IF Test Panel. This bypasses the Upconverter(s) and all Downconverters. If the Bit Error Rate (BER) for the particular data rate under test is within limits, the Modulator and Demodulator are working properly.

The TX IF TEST signal enters the IF Test Panel at J11, via cable W163. This input can be attenuated up to 49dB using Step Attenuator AT2 mounted on the front panel. The signal level of TX IF TEST can be monitored at front panel J1 Test Signal for a fixed -23 dBm signal.

From AT2 the TX IF TEST signal is coupled to a single input, four output Power Splitter A5. The signal is coupled into the A5 at J1 and leaves at J2 - J5 respectively. These four test signals, TX IF TEST are all at the same level for input to the Tropo Modem Demodulator.

11-4 When the Loopback Switches are placed in the loopback position, the receive signal is still allowed to pass. (See Fig 11-1 and FO's). When testing the AN/TRC-170 in IF Loopback while in system, tune the pre and post-selectors of the Downconverters at least 200 MHz off the receive frequency. This will insure the distant receive signal does not interfere with the loopback. At any time when the van is powered up, the IFTP can be placed in loopback with any one or all of the loopback switches, and if the Tropo Modem is operational, DEMUX FRAME light should go out immediately, and the BER SHORT should go to 10 neg 5 BER within 60 seconds, assuming the following conditions are met:

1. IFTP front panel attenuators set to zero. 2. CW/NORM switch set to NORM. 3. MISSION data rate set above 64 Kb. 4. Bandwidth switch set to 7.5 if MISSION data rate set above 2304 Kb. 5. No interfering signal being received through the antenna ports

Note that the DGM equipment does not even have to be turned on for the above to happen.

As can be seen from this discussion, the IF Test Panel is a major troubleshooting tool. It provides a quick and easy way to make an immediate determination if the Tropo Modem modulator and demodulator are working if used as described above. It also provides, through the front panel BNC connector, a means of observing the signal being transmitted, which can be useful to the repair person. Also, by connecting a Spectrum Analyzer to the receive cables coming in to the back of the IFTP from the Down Converters, the receive signal can be observed to determine its spectral content and to see if there is any interference from other signals. A thorough understanding of the uses of the IFTP will greatly increase your competence as a Tropo operator.

11-5

CHAPTER 12

SN-553

FREQUENCY SYNTHESIZER

12-1 PURPOSE: The SN-553 Dual Frequency Synthesizer provides two highly stable phase locked Local Oscillator signals covering from 4.470 to 5.0699 GHz range in 0.1 MHz steps. These Local Oscillator frequencies are used for both the up and down conversion to form your operating frequency. The Synthesizer unit actually has two independent sections that generate two Local Oscillator frequencies. One for transmit to the Up Converter and one for receive for the Down Converters, both of which are Phase Lock Looped to a 10 MHz reference signal from the Transmit Modem Rubidium Standard. It should be noted that the frequency output of the synthesizer is 70 MHz higher than the reading on the thumbwheel switches.

SN-553 DUAL FREQUENCY SYNTHESIZER SPECIFICATIONS

Input DC Power DC Voltages +5v, +15v, & +28v from LVPS #1 and –15v from LVPS #2 Reference Oscillator Frequency 10MHz from Rubidium Standard Reference Oscillator Level -3 dBm to + 3 dBm Output RF Frequency 4.470 to 5.0699 GHz Frequency Selection 0.1 MHz steps Transmit Output One output @ + 14 dBm to + 18 dBm Receive Output Three outputs @ + 11dBm to +15 dBm

SIGNAL FLOW for Frequency Synthesizer- Refer to FO 12-1

1. The Reference Control Loop is common to both transmit and receive sections of the Dual RF Synthesizer. The starting point of the reference loop is the Reference Oscillator A9.

a. The Reference Oscillator A9 is a highly stable 100 MHz oscillator. The 100 MHz IF frequency leaves the A9 and enters a power divider on the A8 Multiplier CCA.

b. The Multiplier Assembly A8 receives the 100 MHz IF signal from the A9. This input is applied to a power divider in the A8 module that splits this signal into three equal level outputs. One output is applied to the Reference CCA A7. The second and third output signals are multiplied by a factor of 46 and 48 to result in an output frequency of 4.6 and 4.8 GHz, and sent to both the RF Converter modules A3 and A4.

c. The Reference CCA A7 receives the 100 MHz IF reference signal from the Multiplier A8. The 100 MHz IF reference signal is divided by 10 to produce a 10 MHz output that is applied to a frequency divider and phase detector. This 10 MHz input to the Phase Detector is compared to the external RF (10 MHz) Rubidium Standard input from the Tropo Modem. The resultant error output circuitry produces a correction voltage, called the AFC Correction Voltage. This correction voltage is sent to the 100 MHz Reference Oscillator A9. The second divide by 10 divider produces a

12-2 1 MHz signal that is sent to both the Transmit CCA A5 and the Receive IF CCA A6. The BITE circuitry for the Dual Frequency Synthesizer is contained on the A7 CCA. This BITE consists of circuits unique to the transmit section, receive section, and the reference control loop circuits common to both.

2. The Transmit VCO Control Loop consists of the Cavity Tuned Oscillator A1, RF Converter A3, and the IF CCA A5. The transmit loop starts with the Cavity Tuned Oscillator A1.

a. The Cavity Tuned Oscillator A1 receives the OSC AFC signal from the IF CCA A5 and is combined with the front panel Transmit-Tune knob controlled signal to drive the VCO to the correct Transmit Local Oscillator frequency.

b. The IF CCA A5 decodes the input from the Transmit-Frequency MHz thumbwheel switch S1. The input of 100 to 300 MHz IF from the RF converter A3 is divided so that an output frequency of 1 MHz is obtained. The amplified error signal out of the IF CCA A5, is sent as the OSC AFC signal to the Cavity Tune Oscillator (VCO) A1 module.

c. The RF Converter A3 module receives the corrected frequency from the Cavity Tuned Oscillator A1. The VCO corrected frequency is passed as the Local Oscillator LO frequency of 4.47 to 5.07 GHz to the Up Converter.

3. The Receive VCO Control Loop consists of Cavity Tuned Oscillator A2, RF Converter A4, and the IF CCA A6. The receive loop starts with the Cavity Tuned Oscillator A2.

a. The Cavity Tuned Oscillator A2 receives the OSC AFC signal from the IF CCA A6 and is combined with the front panel Receive-Tune knob controlled signal to drive the VCO to the correct Receive Local Oscillator frequency.

b. The IF CCA A6 decodes the input from the Receive-Frequency MHz thumbwheel switch S2. The input of 100 to 300 MHz IF from the RF converter A4 is divided so that an output frequency of 1 MHz is obtained. The amplified error signal out of the IF CCA A6, is sent as the OSC AFC signal to the Cavity Tune Oscillator (VCO) A2 module.

c. The RF Converter A4 module receives the corrected frequency from the Cavity Tuned Oscillator A2. The VCO corrected frequency is passed as the Local Oscillator LO frequency of 4.47 to 5.07 GHz to a pair of Down Converters.

12-3 DETAILED MODULE and CIRCUIT CARD FUNCTIONS

Reference Control Loop

The Reference Control Loop is common to both transmit and receive functions of the Dual RF Synthesizer. This Referenced Control Loop is made up of the 100 MHz Reference Oscillator A9, Multiplier Module A8, and the Reference CCA A7.

100 MHz Reference Oscillator A9: This is a highly stable 100 MHz Oscillator. The 100 MHz IF oscillator signal leaves the A9 and enters a power divider on the Multiplier A8 module.

Multiplier Module A8: The A8 receives the 100 MHz IF oscillator signal from the Reference Oscillator A9. This input is applied to a power divider in A8 module that splits the power level into three equal outputs. One output is applied to the Reference CCA A7. The second and third output signals are multiplied by a factor of 46 and 48 to result in an output frequency of 4.6 and 4.8 GHz. There are two outputs on each of the multipliers. One output each goes to the multiplier BITE on the A8 CCA. This monitors for a 6dB loss. If either output drops 6 dB or more, a multiplier fault is sent to the Reference CCA A7. The other output of the X46 and X48 multipliers goes to both transmit and receive electronic switch circuitry on the A8. This transmit electronic switch has a 4.6 GHz and a 4.8 GHz input. This transmit electronic switch gets an input from the decoder circuit on the IF CCA A5. This input tells the switch whether to select the 4.6 GHz or 4.8 GHz that will be mixed with the Local Oscillator and will get the IF in range to the 100 to 300 MHz signals. This receive electronic switch has a 4.6 GHz and a 4.8 GHz input. This receive electronic switch gets an input from the decoder circuit on the IF CCA A6. This input tells the switch whether to select the 4.6 GHz or 4.8 GHz signal that will be mixed with the Local Oscillator to get the IF in the range of 100 to 300 MHz.

Reference CCA A7: The 100 MHz IF input is received by the A7 CCA from the A8 module, and then divided by 10 to produce a 10 MHz signal. This 10 MHz signal is routed two places. First to a phase detector circuit and then to a divide by 10 circuit. This signal is then compared to the 10 MHz Rubidium Standard from the Modem by a phase detector circuit. If these two 10 MHz signals are not the same, then an error signal is generated by the A7 and sent to the Reference Oscillator A9 where it acts as the AFC voltage to phase lock the 100 MHz Reference Oscillator. When the reference loop is unlocked, both transmit and receive IF LEDs will activate. The second part of 10 MHz signal was divided by a selected divisor to produce a signal with an output frequency of 1 MHz that is sent to both the A5 and A6 IF circuit cards.

The Transmit Loop: The Transmit VCO Control Loop consists of the Cavity Tuned Oscillator A1, RF Converter A3, and the IF CCA A5. The transmit loop starts with the Cavity Tuned Oscillator A1.

12-4 Cavity Tuned Oscillator (VCO) A1: The output of the VCO is set by the transmit thumbwheel switch S1. The VCO oscillates at a frequency 70 MHz above the frequency set by the thumbwheel switch. The VCO is phased locked onto the correct frequency by the AFC voltage signal from the IF CCA A5. This voltage is 1 volt for every 1 KHz the VCO is off of the desired frequency. The 4.47 GHz to 5.07 GHz is sent over to the RF A3 Converter module.

RF Converter A3: The 4.47 GHz to 5.07 GHz Local Oscillator signal is sent to the A3 RF Converter, where it is sent to a coupler. The coupler has three outputs. The first output is sent to the converter/mixer, where the L.O. is mixed with the 4.6 or 4.8 GHz coming in at J2 of A3 RF Converter that was selected by the decoder circuit to produce a 100-300 MHz IF output. This output is sent out to the IF CCA A5 to be used in the reference loop to produce the 1 MHz signal which will eventually become your OSC AFC. The second output of the coupler goes to a 20 dB isolator, then out a 2 dB pad AT1 where it is routed to the Up Converter. The output of the LO signal is monitored by a detector, and the detector output is sent to the Reference CCA A7.

IF CCA A5: The IF CCA A5 decodes the input from the Transmit-Frequency MHz thumbwheel switch S1. The input of 100 to 300 MHz IF from the RF converter A3 is divided so that an output frequency of 1 MHz is obtained. The amplified error signal out of the IF CCA A5, is sent as the OSC AFC signal to the Cavity Tune Oscillator (VCO) A1 module.

Transmit Frequency Switch S1: This switch sends a Binary Coded Decimal (BCD) to the Decoder circuitry on the IF CCA A5. This decode circuitry decodes the transmit frequency from the thumbwheel switch S1.

The Receive Loop: The Receive VCO Control Loop consists of the Cavity Tuned Oscillator A2, RF Converter A4, and the IF CCA A6. The receive loop starts with the Cavity Tuned Oscillator A2.

Cavity Tuned Oscillator (VCO) A2: The output of the VCO is set by the receive thumbwheel switch S2. The VCO oscillates at a frequency 70 MHz above the frequency set by the thumbwheel switch. The VCO is phased locked onto the correct frequency by the AFC voltage signal from the IF CCA A6. This voltage is 1 volt for every 1 KHz the VCO is off of the desired frequency. The 4.47 GHz to 5.07 GHz is sent over to the RF A4 Converter module.

RF Converter A4: The 4.47 GHz to 5.07 GHz Local Oscillator signal is sent to the A4 RF Converter, where it is sent to a coupler. The coupler has three outputs. The first output is sent to the converter/mixer, where the L.O. is mixed with the 4.6 or 4.8 GHz coming in at J2 of A4 RF Converter that was selected by the decoder circuit to produce a 100-300 MHz IF output. This output is sent out to the IF CCA A6 to be used in the reference loop to produce the 1 MHz signal which will eventually become your OSC AFC. The second output of the coupler goes to the A10 power divider. This

12-5 power divider has three outputs. The fist LO output is terminated into a dummy load. The other two LO Outputs are sent to the Down Converters.

IF CCA A6: The IF CCA A6 decodes the input from the Receive-Frequency MHz thumbwheel switch S2. The input of 100 to 300 MHz IF from the RF converter A4 is divided so that an output frequency of 1 MHz is obtained. The amplified error signal out of the IF CCA A6, is sent as the OSC AFC signal to the Cavity Tune Oscillator (VCO) A2 module.

Receive Frequency Switch S2: This switch sends a Binary Coded Decimal (BCD) to the Decoder circuitry on the IF CCA A6. This decode circuitry decodes the receive frequency from the thumbwheel switch S2.

12-6 DUAL SYNTHESIZER SN-553

7 8

Item Description

1 TRANSMIT-TUNE - meter and control – Green segment indicates when internal voltage controlled oscillator is phase locked. Control tunes the transmit VCO (Knob has locked and unlocked position). 2 TRANSMIT SUMMARY FAULT - LED (red) - Indicates a fault in the transmit circuitry or incorrect tuning. 3 TRANSMIT FREQUENCY-TUNE – five-digit thumbwheel switch - Set for desired transmit frequency. 4 RECEIVE FREQUENCY-TUNE - five-digit thumbwheel switch - Set for desired receive frequency. 5 RECEIVE SUMMARY FAULT - LED (red) – Indicates a fault in the receive circuitry or incorrect tuning. 6 RECEIVE-TUNE - meter and control – Green segment indicates when internal voltage controlled oscillator is phase locked. Control tunes the receive VCO (Knob has locked and unlocked position). 7 TRANSMIT TUNNING KNOB – this knob is used to tune the transmit synthesizers cavity tuned oscillator. Adjust the knob until the meter needle is in the center of the green segment. Then adjust to the extreme left and right, then back to the center of the green segment. Make sure that the Transmit Summary fault LED is not illuminated. 8 RECEIVE TUNNING KNOB - this knob is used to tune the receive synthesizers cavity tuned oscillator. Adjust the knob until the meter needle is in the center of the green segment. Then adjust to the extreme left and right, then back to the center of the green segment. Make sure that the Receive Summary fault LED is not illuminated.

12-7 DUAL FREQUENCY SYNTHESIZER SN-553 component location

REMARKS: The following six items are interchangeable A1: Cavity Tuned Oscillator (VCO) WITH A2: Cavity Tuned Oscillator (VCO) A3: RF Converter Module WITH A4: RF Converter Module A5: IF Circuit Card Assembly (CCA) WITH A6: IF Circuit Card Assembly (CCA)

A7: Reference Circuit Card Assy NOT A8: Multiplier Module A9: 100 MHz Reference Oscillator

12-8 DUAL SYNTHESIZER SN-553 REAR VIEW

Connector Jack Description J1 Power DC Voltages Input J2 Dual Synthesizer Fault Alarms Output J3 Transmit Local Oscillator output of 4.47 to 5.07 GHz to Up Converter. J4 10 MHz Reference Input J5 Receive Local Oscillator 4.47 to 5.07 GHz output to Dummy Load. J6 Receive Local Oscillator output of 4.47 to 5.07 GHz to D/C #1 and to D/C # 3. J7 Receive Local Oscillator output of 4.47 to 5.07 GHz to D/C #2 and D/C # 4 only used in the V2. GND Ground Connection

12-9 Synthesizer BITE LED Indications per Fault Conditions

Table 12-1 Synthesizer A7 BITE Lamp (LED) display per fault conditions

INTERNAL FAULT FAULT CONDITION LED INDICATION DS1 The Reference Lock is used by both transmit and receive BITE to indicate a malfunction of the reference loop. DS2 Transmit IF Lock Fault – If the VCO phase lock is at a low or fault level, indicating the VCO is unlocked. DS3 Receive IF Lock Fault – If the VCO phase lock is at a low or fault level, indicating the VCO is unlocked. DS4 Multiplier Fault – monitors for a 6 dB loss of the 4.6 and 4.8 GHz signals. DS5 Transmit VCO Power Out Fault – activates if the power level drops below +11 dBm. DS6 Receive VCO Power Out Fault – activates if the power level drops below +11 dBm.

Table 12-2 Synthesizer Transmit & Receive Summary (LED) display per fault conditions.

Transmit Summary LED DS1 on the front Receive Summary LED DS2 on the front panel will activate when any of these five panel will activate when any of these five conditions occur. conditions occur. 1. DS5 LED on the A7 CCA is activated when the 1. DS6 LED on the A7 CCA is activated when the Control Loop drops below +11 dBm. Control Loop drops below +11 dBm. 2. DS2 LED on the A7 CCA is activated when 2. DS3 LED on the A7 CCA is activated when VCO phase lock is at a low or fault level VCO phase lock is at a low or fault level indicating the VCO is unlocked. indicating the VCO is unlocked. 3. DS4 LED on the A7 CCA is activated when 3. DS4 LED on the A7 CCA is activated when either multiplier output level drops 6 dB or more. either multiplier output level drops 6 dB or more. 4. DS1 LED on the A7 CCA is activated by a 4. DS1 LED on the A7 CCA is activated by a Transmit Reference Lock fault. Receive Reference Lock fault. 5. Transmit Error is initiated if the thumbwheel 5. Receive Error is initiated if the thumbwheel switch is broken or in between switch selections. switch is broken or in between switch selections. This fault won’t light a fault LED on the A7 CCA. This fault won’t light a fault LED on the A7 CCA.

12-10 Troubleshooting the Synthesizer

The following information is found on the under side of the top cover on the Frequency Synthesizer.

Bite Indication Corrective Action 1st Replace the A7 Reference CCA 6 2nd Check 10 MHz Reference In on J4 3rd Replace the A9 100 MHz Reference 1st Replace the A5 Transmit IF CCA 2 2nd Replace the A3 Transmit RF and Converter Assembly 3rd Replace the A1 Transmit Cavity VCO 1st Replace the A6 Receive IF CCA 5 2nd Replace the A4 Receive RF and Converter Assembly 3rd Replace the A2 Receive Cavity VCO 1 Replace the A8 Multiplier 1st Replace the A1 Transmit Cavity VCO 3 2nd Replace the A3 Transmit RF and Converter 1st Replace the A2 Receive Cavity VCO 4 2nd Replace the A4 Receive RF and Converter 1,6 Replace the A9 100 MHz Reference

After replacing LRU’s as specified above without correcting failure, then also: 1) Replace the A7 Reference CCA. 2) Replace the A4 multiplier.

If external light is on and no internal indicators are on: A) Check Frequency setting on thumb wheel switch, 4.4000-4.9999 B) Replace the corresponding IF CCA A5 or A6 C) Replace the A7 Reference CCA D) Replace the thumb wheel switch

Back

(DS1) 6 Reference CCA Out of Lock (DS3) 5 Receive IF CCA out of Lock (DS6) 4 Receive Power Out LOW (DS5) 3 Transmit Power Out LOW (DS2) 2 Transmit IF CCA Out of Phase Lock (DS4) 1 Multiplier Failure

Front

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12-12

CHAPTER 13

AM-7027

Up Converter-Amplifier

13-1 Unit 3 – Operations Student Handout Operations PC, Tropo Radio Tuning Checklist

If an unsafe procedure is spotted, stop the procedure immediately.

Up Converter 1. Set the up converter for transmit operating frequency.

Down converter 1. Set the down converter for operating frequency. Verify Freq is 100 MHZ away from XMT 2. Adjust the Pre-Selector Filter. 3. Adjust the Post Selector Filter. 4. Turn the Noise Test Switches OFF.

Dual RF Synthesizer 4. Set the transmit side to the operating frequency. Tune the Phase Lock Loop Circuit: Adjust the Tuning knob until the meter is in the green area and the summary fault is OFF. 5. Set the receive side to the operating frequency. Tune Phase Lock Loop Circuit: Adjust the Tuning knob until the meter is in the green area and summary fault is OFF.

2900 Titan Row, Suite 142 Orlando, FL 32809 (407) 854-1950 Sheet 1 of 1 PURPOSE: The AM-7027 Transmit Amplifier Converter is commonly called the Up Converter. The Up Converter produces a 4.4 to 5.0 GHz modulated output from a Local Oscillator LO input of (4.47 to 5.07 GHz) and a modulated 70 MHz IF input. The SHF output of the Up Converter is used as drive input to the HPA.

AM-7027 UP CONVERTER SPECIFICATIONS

Input DC Power DC Voltages +5v & +15v, from LVPS #1 and –15v from LVPS #2 RF Frequency 4.4 to 5.0 GHz Frequency Selection 5 MHz steps Local Oscillator (LO) 4.47 to 5.07 GHz Frequency Input Local Oscillator (LO) +14.5 dBm to +17.5 dBm Input Level IF Input 70 MHz IF Input Level -3dBm to +3dBm IF Input Impedance 75 , unbalanced Output LOS Mode +26 dBm to 28 dBm TROPO Mode +23 dBm to 25 dBm

SIGNAL FLOW for Up Converter – Refer to FO 13-1

(1) The RF Assembly A1 receives two inputs. The 70 MHz IF input signal from the TROPO Modem and the Local Oscillator LO input signal of 4.47 to 5.07 GHz from the Transmit Synthesizer, to produce a SHF difference frequency of 4.4 to 5.0 GHz, that is sent to the Filter Assembly A3.

(2) The SHF signal from the RF Assembly A1 enters the first section of the Bandpass Filter Assembly A3, a ganged filter arrangement Pre-Select that rejects out of band spurious responses and maintains the bandpass frequency. It is marked in 5 MHz increments. After filtering, the output is routed to the A2 for amplification. .

(3) The Intermediate Amplifier Assembly A2 takes the input from the A3 module and amplifies the signal to a 1-watt output. The amplified signal is routed through a directional coupler and sent out to the A3 Filter Assembly. A RF sample is sent to the RF detector on the A1 module.

(4) The RF output of the IPA A2 module is routed to A3 for filtering. The second section of the Bandpass Filter Assembly A3 is a ganged filter arrangement Post-Select Bandpass Filter that is used to filter this RF signal. The RF Signal is then sent through a directional coupler and out to the RF OUTPUT connector on the front panel. A coupled signal is sent to a detector. When the level is too low, the summary alarm DS1 on the front panel is illuminated. (5) The BITE CCA A4 performs the following functions: detects fault signals from the Up Converter assemblies, provides lamp indication signals, receives logic signals from the Down Converters and

13-2 HPA to have the output of the Up Converter attenuated by 40db as required. Controls the Up Converter output power. Receives logic commands from the HPA for the LOS or TROPO mode of operation.

DETAILED MODULE and CIRCUIT CARD FUNCTIONS

RF Assembly-Mixer A1: The RF Converter-Mixer Assembly A1 consists of: a converter-mixer, circulators, variable voltage attenuator, voltage-level reference circuits and a diode fault sensor. The converter-mixer accepts the Local Oscillator LO frequency of 4.47 to 5.07 GHz input from the Transmit Synthesizer and the 70 MHz IF from the Transmit Modem. These two frequencies are mixed to produce the difference SHF frequency of 4.4 to 5.0 GHz. This difference frequency is then passed to the variable voltage attenuator AT1. To maintain the IPA power amplifier A2 within gain compression limits, the voltage variable attenuator AT1 is a voltage controlled device used to establish the desired output power level. The attenuated output to Filter A3 and the IPA A2 Module is controlled BITE CCA A4. The output of the RF Assembly-Mixer Module A1 is sent to the Filter Assembly A3.

Bandpass Filter Pre-Selector A3: The filter assembly A3 consists of two filter sections, both physically ganged together to permit frequency tuning from one knob. The input SHF signal of 4.4 to 5.0 GHz is passed to the first section of filter FL1A that is a bandpass filter. This filter section is a multi-cavity type for limiting out of band spurious effects and filtering converter mix products (such as upper and lower sideband) before the SHF signal is sent to the IPA Assembly A2. It has a bandwidth of 7MHz, and is adjusted from the front panel. The Bandpass Filter FL1 front panel scale is made of a paper strip located behind the Plexiglas. This paper strip is marked in 5 MHz increments from 4400 – 5000 MHz. STOP is written at each end of the strip. DO NOT ADJUST THE FILTER PAST THIS POINT!

IPA Assembly A2: The incoming SHF signal from the Bandpass Filter Pre-Selector A3 is sent to the IPA Assembly A2. This module attenuates signal power, monitors the power level for fault detection, and amplifies the converter signal to a 1-watt output at J3. The IPA output to the Filter Assembly A3 is regulated by a power loop involving reference settings, combined with RF level detection that is a controlled voltage feedback through the BITE CCA A4 to a variable attenuator AR1 in the A2 module. The SHF output signal is then sent to the Bandpass Filter Post-Selector A3. A fault condition within the IPA module is indicated by the IPA ASSY (LED) DS1 on the BITE CCA A4.

Bandpass Filter Post-Selector A3: The amplified SHF output of the IPA A2 module is applied to the Bandpass Filter Post-Selector A3 module. The Filter Assembly A3 accepts the amplified signal from the IPA Module A2. It filters for broadband noise, provides voltage reference control in the LOS or TROPO mode. Also provides voltage threshold detection for BITE faults and voltage monitoring, and maintains RF output power constant against voltage and temperature variations. The filter assembly A3 consists of the following components: a filter FL1B, circulator, directional coupler, reference voltage control/monitor assembly and a diode detector. It also contains a small circuit card the A1 RF level reference CCA, when either LOS or TROPO mode of operation is desired. It contains variable resistors that are used to properly set the output of the Up Converter

13-3 when either LOS or TROPO mode of operation is selected. The Post-Selector section of this filter has a bandwidth of 7 MHz. The filtered RF output is sent to the HPA. The Bandpass Filter FL1 front panel scale is made of a paper strip located behind the Plexiglas. This paper strip is marked in 5 MHz increments from 4400 – 5000 MHz. STOP is written at each end of the strip. DO NOT ADJUST THE FILTER PAST THIS POINT!

BITE Assembly CCA A4: This circuit card performs the following functions: detects fault signals from the Up Converter assemblies, provides lamp indication signals, receives logic signals from the Down Converters and HPA to have the output of the Up Converter attenuated by 40db as required. Controls the Up Converter output power. Also receives logic commands from the HPA for the LOS and TROPO mode of operation selected by the operator at the HPA. It also serves as a low voltage distribution junction box for the Up Converters assemblies. As the RF levels are monitored, fault signals are detected by the BITE CCA. The CCA will either provided a loop response in the form of corrective control signal or a RF inhibit.

Table 13-1 Up Converter BITE Lamp (LED) displays per fault conditions

RF INHIBIT SUMMARY RF ASSY IPA FAULT LED FAULT LED OUT ASSY OUT CONDITION (PANEL) LED LED Off Off Off Off Normal operation of Up Converter On On On On RF inhibit by external inhibit (RCVR Inhibit or XMT Inhibit signals) or faulty BITE CCA A4. Off On On On RF drive signal missing or RF assembly A1 faulty. Off On Off On RF output from IPA missing. Faulty IPA A2. Off On Off Off RF output from filter missing. Faulty filter A3. Off Off On Off RF level over or under threshold at A1 CR3.

13-4 AMPLIFIER CONVERTER (UP CONVERTER)

Item Description 1 RF OUTPUT Connector – Up Converter Output fed to the High Power Amplifier for Amplification in the TROPO mode. In the LOS Mode the RF transmission passes through the HPA (without amplification) to the antenna. 2 FREQUENCY Adjustable Filter - Tuned to transmit operating frequency. Knob is turned to operating frequency on the window dial. Outer ring knob is turned in the LOCK direction to lock knob. 3 SUMMARY FAULT LED (red) - Indicates a fault in one of the Up Converter modules, or a RF inhibit fault.

13-5

UP CONVERTER SUBASSEMBLY LOCATIONS

A1 RF ASSEMBLY - Mixes/Amplifies 70 MHz input from the Tropo Modem, and the 4.47 to 5.07 GHz from the transmit side of the dual frequency synthesizer to produce a difference operating SHF frequency of 4.4 to 5 GHz. A2 INTERMEDIATE POWER AMPLIFIER (IPA) - Is the final Amplifier in the LOS mode and an intermediate amplifier in the Tropo mode. A3 FILTER ASSEMBLY - Is a multi-channel band pass filter with a band pass of +/- 3.5 MHz (7 MHz BW). A4 BITE CCA – Reports internal faults to the Alarm Monitor and lights the summary alarm LED on the front panel. In conjunction with the A3-A1 (Reference level control module) controls the output of the IPA for LOS or HPA mode of operation. Also reduces the output power of the RF Assembly and the IPA modules, if a RF inhibit is received from the (Down Converters RF Overload) or from the (HPA High VSWR). The BITE CCA also has internal fault LEDs on it that light when failure of the subassemblies occur; (DS1 – IPA Low Power Fault), (DS2 - RF inhibit fault), and (DS3 - RF Assembly Fault).

13-6

UP CONVERTER CABLE CONNECTORS (RIGHT REAR)

Connector Jack Nomenclature J1 Power DC Voltages Input J5 U/C RF Inhibit from D/C 1 & 3 Input Fault Alarms Output J6 U/C RF Inhibit from HPA 1 & LOS – TROPO Mode Select Input J7 U/C RF Inhibit from HPA 2 Input *Only used in the V2. J9 Local Oscillator (LO) from Transmit Synthesizer Input J10 70 MHz IF from Transmit TROPO Modem Input GND Ground Connection

13-7 Tropo Upgrade COMTECH Modem Loopbacks Bi-Directional Port Loopback