ITS Telecom ITS-5523 Technical Manual

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TECHNICAL MANUAL

EXHIBIT II

(PRELIMINARY)

ITS- 5523

DIGITAL
TRA NSMITTER

REV: 0

102 Rahway Road
McMurray, PA 15317 USA
Phone [phone]
FAX [phone]

ITS-5523

DIGITAL TRANSMITTER

TABLE OF CONTENTS

I. INTRODUCTION:

II. SYSTEM ITS-5523: ......................................................................................................................................... 1555-1103

A. SYSTEM DESCRIPTION
B. SPECIFICATIONS
C. FRONT PANEL LED INDICATORS AND CONTROLS
D. PRINTED CIRCUIT BOARD INDICATORS AND DESCRIPTIONS
E. SYSTEM ALIGNMENT PROCEDURE
F. REAR PANEL CONNECTIONS
G. REMOTE CONTROL INTERFACE

III. UPCONVERTER/AMPLIFIER SECTION:

A. DRAWINGS:

1. BLOCK DIAGRAM.......................................................................................................1554-3010

2. INTERCONNECT .......................................................................................................... 1554-8010

B. UPCONVERTER/AMPLIFIER SUBASSEMBLIES

VI . MAINTENANCE:

A. This section contains information on troubleshooting, problem analysis and repair procedures for the
ITS-5523.

ITS-5523

SYSTEM DESCRIPTION

The ITS-5523 Digital Transmitter is designed to operate in conjunction with a QAM digital IF modulator. The
Modulator used with this model is a Comstream CM720M. The ITS-5523 incorporates Automatic Level Control
(ALC) and Automatic Gain Control (AGC), which serve to maintain a constant output power level.

Combining the latest in GaAsFET amplifier technology and space saving design, the ITS-5523 delivers an output
power of 5 watts (average).

The unit's circuitry is enclosed in a tray assembly designed for mounting in a standard 19" equipment rack. The unit
comes complete with slide rail mounting hardware to allow the tray to move in and out of the rack for ease of service.
The outside dimensions of the tray assembly are 19" x 21" x 8.75" (W x D x H).

The ITS-5523 is factory calibrated for a front panel power meter reading of 100%, which represents the rated output
power of the unit (unless otherwise specified).

THEORY OF OPERATION

The 64 QAM digital IF signal, derived from the digital IF modulator, is applied to the rear of the tray (J2).

The input signal is fed to the IF Amplifier Board (1521-1101), which provides impedance matching and
amplification of the IF input signal. The output of the Impedance Matching Board is fed to a SAW Filter
Board (1600-1209), which attenuates any spurious signals outside the channel bandwidth. The output of
the SAW Filter Board is connected to the IF Delay Board (1165-1018), which contains two sections of delay
equalization to compensate for Group Delay created by external filters.

The IF Delay Board output is fed to the Response Corrector Board (1034-1205). On this board are three

adjustable notch filters which correct for nonlinearities in the IF response. The output signal (J5) is
connected to the input of the ALC/AGC Board (1022-1102).

The signal enters the board on J1, and after a 2 dB pad, a IF band-pass filter, and a second 2 dB pad, is

adjusted in level by PIN Diode Attenuator/ALC circuitry. This circuitry takes a peak-detected sample of the
IF signal and generates an ALC voltage, which biases the PIN Diode Attenuator. The ALC circuitry senses
any change in the IF level and automatically adjust the loss of the PIN attenuator to compensate, thereby
maintaining a constant IF output level regardless of minor changes in the input signal.

Next, the IF signal is fed to a loop through at J2 to a series of two boards. The first, the Linearity Corrector

Board (1034-1201) pre -distorts the IF signal to compensate for compression in later stages of the system.
The second board, the IF Phase Corrector Board (1227-1250) corrects for any phase error, whic h may be
introduced by the amplifiers later in the system. The phase and linearity corrected signal reenters the
ALC\AGC Board at J3 and after an IF filter identical to that used on the main input of the board (J1), is
applied to a Wilkinson Splitter. The main output of the splitter is fed to an AGC pin diode attenuator circuit.
The AGC pin diode attenuator, which functions in the same manner as the ALC pin attenuator diode
attenuator uses a DC level generated externally by a peak -detected sample of the output to adjust the loss of
the attenuator. The AGC circuitry maintains a constant level regardless of minor changes in the IF signal.

The AGC circuit can be bypassed by switch S2. When the AGC is disabled, the loss through the AGC PIN

attenuator is adjusted by the Manual Gain potentiometer R101, which directly controls the output in a
manual fashion. The AGC/AGC output (J4) is fed to the input of the Response Corrector Board (1034-1205),
with form and function identical to the response corrector above. The Response Corrector Board output
(J4) is connected to the IF input of the Upconverter Module (1519-1125).

ITS-5523

THEORY OF OPERATION - Continued

A L.O. (local oscillator) signal is generated on the UHF Generator Board. This Board is comprised internally

of a voltage controlled crystal oscillator circuit and a x8 multiplier consisting of three x2 broadband doublers
(23 = x8) which produces the local oscillator signal (L.O.) signal.. The oscillator circuit is a modified Colpitts
design and the crystal is mounted in an oven set at 60° C and operates at 1/24 of the local oscillator
frequency. The output of the UHF Generator Board is applied to a x3 Multiplier and then to the input of a
mixer which is located on the Upconverter Board. The voltage controlled crystal oscillator circuit within the
UHF Generator Board is controlled by the VHF PLL Board, which locks the L.O. signal to a precise external
10 MHz reference, which is applied to the rear of the tray at jack J6. A sample of the L.O. signal is available
at the front panel jack J3. A 50 kHz reference sample is available at jack J5.

The PLL circuit on the VHF PLL Board divides a sample of the channel VCXO frequency and compares it to

the reference frequency (50 KHz) also generated by the VHF PLL Board. The difference between the phase
of the reference frequency and the divided down VCXO frequency sample causes the PLL IC to create an
error output voltage called Automatic Frequency Control (AFC) voltage, which is used to bias a variable
capacitor in the channel VCXO.

The Upconverter Board generates a RF signal from the difference between the L.O. signal and the IF signal

(LO - IF). The output of the Upconverter Board is sent through a Four Stage Cavity Filter w/Trap (2000­1240, which attenuates any undesired signals that may have been generated by the Upconverter Board
during the mixing process.

The output from the Four Stage Cavity Filter (2000-1240) is sent to the Three Stage Amplifier Module (1516-

1108), which consist of three cascaded GaAs FET amplifiers (FLL101ME driving a FLL351ME driving a
FLL200IB-3) with an averall gain of 36 dB. The output of the Three Stage Amplifier (J2) is connected to the
input of the 50W Amplifier (1512-1107).

The signal enters the input the 50-Watt Amplifier Module at J1 and amplified by GaAs FET Q101 (FLL2008-

3). Then the signal is split four ways by three Wilkinson in phase couplers and amplified by GaAs FET
amplifiers Q201, Q301, Q401, and Q501 (all FLL2008-3's). The signal is then combined by three Wilkinson in
phase couplers and fed to the output of the module at jack J2. The output is fed to a Circulator Kit (A50),
then to the RF output jack at the rear of the tray (J10).

Two 20 dB micro -strip couplers located within the 50-Watt amplifier Module provide a forward and reflected

sample of the final output signal. Both samples are sent to the Dual peak Detector Board (1512-1147), which
detects each sample and provides a forward and reflective metering voltage, which drives the transmitter’s
front panel.

The DC biasing of each FET is controlled and filtered by the corresponding daughter boards (D1, D2, D3,

D4, and D5), Which are soldered directly to the motherboard. The DC bias drain to source currents are set
by adjusting the negative gate to source voltages which are adjusted by potentiometers on the daughter
boards.

ITS-5523

THEORY OF OPERATION - Continued

The Six Section Bias Board (1519-1136) supplies the two amplifier modules with both +10 VDC (operating

voltage) and -5 VDC (bi as voltage).

The Transmitter Control Board (1555-1214) provides the capability to control and monitor the operating

status of the transmitter. The board is designed to protect the transmitter in the event of the following
faults: over temperature, loss or reduction in output power and loss of the -5 VDC GaAsFET bias voltage.
The Transmitter Control Board also provides the capability to remotely control and monitor the booster
status by providing external remote connections via the Connector Assembly Board (1519-1109) jacks J16
and J17 at the rear of the tray.

The transmitter may be configured to be powered by either a 115 VAC/60 Hz or 230V AC/50 Hz source. The

AC source enters the tray at jack J1. The AC source passes through a line filter and is distributed to a
terminal block (TB1). Varistors VR1, VR2, VR3 and VR4 provide transient and over voltage protection to the
transmitter. The rear panel circuit breaker applies AC voltage to the input of the toroid transformer.

The toroid transformer provides (2) 15 VAC secondary windings. The first winding is sent to a full wave

bridge rectifier which supplies a positive 18 VDC to several positive voltage regulators located on the DC
Power Supply Board. The second winding is applied to the +12 VDC Power Supply Board (1512-1119) which
powers the 12 VDC cooling fan. The second winding is also applied to a full wave bridge rectifier circuit on
the DC Power Supply Board whose output is sent to several negative voltage regulators. Two +12 VDC
switching supplies (SPL250-1012) rated at 21 amperes are used to supply the GaAs FET Amplifier Modules
with power.

ITS-5523

THEORY OF OPERATION - Continued

AC Voltage Source

The transmitter may be configured to be powered by either a 115 VAC/60Hz or 230 VAC/50Hz by the

following procedures.

230 VAC to 115 VAC Operation

Locate the 10 position terminal block (TB1) within the transmitter. Referring to Interconnect drawing 1555-

8102, remove the jumper between positions 2A and 3A. Remove the jumper between p ositions 4A and 5A.
remove VR1 (250V), VR2 (275V), and VR4 (275V) from terminal block TB1. Connect a jumper between
positions 3A and 4A. Connect another jumper between positions 5A and 6A. Move the jumper wire from
the 230 VAC terminal of the + 12VDC switching power supplies (A9 and A19) to the 115VAC terminal.
Install VR3 (150V) across positions 1A and 6A. Install VR4 (150V) across positions 1A and 3A.

115 VAC to 230 VAC Operation

Locate the 10 position terminal block (TB1) within the transmitter. Referring to Interconnect drawing 1555-

8102, remove the jumper between position 3A and 4A. Remove the jumper between positions 5A and 6A.
remove VR1 (130V), VR2 (150V), VR3 (150V), and VR4 (150V) from terminal block TB1. Connect a jumper
between position 2A and 3A. connect another jumper between positions 4A and 5A. Move the jumper wire
from the 115 VAC terminal of the +12 VDC switching power supplies (A9 and A19) to the 230 VAC terminal.
Install VR1 (250V) across positions 8A and 10A. Install VR2 (275V) across positions 3A and 6A. Install VR3
(275) across positions 1A and 3A.

ITS-5523 DIGITAL TRANSMITTER TRAY (11555-1102)

SPECIFICATIONS

Technical Specifications

Type of Emissions...........................................................................................................................6M00D7W

Frequency Range............................................2150 to 2162 and 2500 to 2686 MHz (any 6 MHz channel)

Output Power Rating.......................................................................................... 5 to 10 watts total average

DC voltage and total current of final amplifier stage........................................... 10 volts DC at 24 amps

(Class A - Not RF power dependent)

Performance Specifications

Operating Frequency Range................................................................2150 to 2162 and 2500 to 2686 MHz

RF output - Nominal:

Power........................................................................................ 5 to 10 watts average (adjustable)

Impedance.............................................................................................................................50 ohms

Connector...............................................................................................................................Type N

Input: (Digital QAM) ...........................................................................................................................44 MHz

Out-of-Band Power..........................................................................................-38 dB max (at channel edge)

-60 dB max (0.5 MHz above channel edge and 1.0 MHz below channel edge)

Harmonic Products...........................................................................................................................-60 dB max

Electrical Requirements

Power Line Voltage.................................................................................................117 VAC, ±10%, 60 Hz or

220 VAC ±10%, 50 Hz

Power Consumption...........................................................................................................................175 watts

Environmental

Maximum Altitude............................................................................................................12,000 feet (3,660m)

Ambient Temperature.......................................................................................................................0° to 50°C

Mechanical

Dimensions: (WxDxH)..........................................................19" x 21" x 8.75" (48.3cm x 53.3cm x 22.24cm)

Weight: ................................................................................................................................... 30 lbs. (13.6 kgs)

ITS-5523

FRONT PANEL METER, CONTROLS, AND LED INDICATORS

The ITS-5523 front panel provides operating controllability, metering capability and status indication. These features
provide an effective means to determine the over -all operating status of the transmitter at a glance.

Controls

ON/OFF (Rear Panel) Provides control of AC to the tray as well as circuit
protection.

OPERATE (DS2) Places transmitter into the Operate mode.

STANDBY (DS1) Places transmitter into the Standby mode.

A front panel meter is provided to monitor two levels. A rotary switch, located next to the meter, is used
to select the following metered parameters:

% FWD. PWR. (0-100%) Indicates percentage of output power (top scale).

% REFL. PWR. (0-100%) Indicates percentage of reflective power (top scale).

Status Indicators

Operating status indicators are provided for front panel viewing. From left to right they are:

PLL LOCKED (DS6)-GREEN Illumination indicates that the UHF generator is locked.

PLL REFERENCE PRESENT Illumination indicates that an internal or external reference
(DS4)-GREEN is present.

THERMAL INTERLOCK Illumination indicates that an over temperature fault is not
(DS3)-GREEN present in the amplifier

OUTPUT FAULT (DS7)-RED Illumination indicates that a fault condition exist.

OPERATE (DS2) Illumination indicates the transmitter is enabled.

STANDBY (DS3) Illumination indicates that the transmitter is disabled.