Crescend Technologies P25XXHA3 User Manual

INSTALLATION AND OPERATING

MANUAL

P25 Series UHF

CONTINUOUS DUTY

POWER AMPLIFIER

Crescend Technologies

140 E. State Parkway

Schaumburg, IL 60173

Tel: [phone]
Fax: [phone]

[e-mail]

www.crescendtech.com

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1 GENERAL DESCRIPTION

1.1 INTRODUCTION

This manual contains installation and operating information for the Crescend High Power Amplifier.
The manual is organized into multiple sections as follows:

1 GENERAL DESCRIPTION .................................................................................................................... 3

1.1 INTRODUCTION .................................................................................................................. 3

1.2 PRODUCT DESCRIPTION ................................................................................................... 3

2 INSTALLATION ..................................................................................................................................... 5

2.1 INSTALLATION INSTRUCTIONS ......................................................................................... 5

2.2 INITIAL STARTUP ................................................................................................................ 6

3 OPERATING INFORMATION ............................................................................................................... 7

3.1 INTRODUCTION .................................................................................................................. 7

3.2 STATUS INDICATORS AND MONITOR CONNECTOR ...................................................... 7

3.3 DETAILED STATUS INDICATOR AND MONITOR CONNECTOR INFORMATION ............ 9

3.4 DIGITAL COMMUNICATION INTERFACE (RS232) ...........................................................13

3.5 POWER SET CONTROL .....................................................................................................17

4 TROUBLESHOOTING ..........................................................................................................................18

4.1 INTRODUCTION .................................................................................................................18

4.2 TROUBLESHOOTING .........................................................................................................18

4.3 RETURN FOR SERVICE PROCEDURES...........................................................................20

4.3.1 OBTAINING RMA ........................................................................................................20

4.3.2 REPACKAGING FOR SHIPMENT ..............................................................................20

5 MAINTENANCE ...................................................................................................................................21

5.1 INTRODUCTION .................................................................................................................21

5.2 PERIODIC MAINTENANCE .................................................................................................21

5.3 CLEANING AIR INLETS/OUTLETS .....................................................................................21

6 RF ENERGY EXPOSURE ....................................................................................................................22

6.1 RF ENERGY EXPOSURE AWARENESS, CONTROL INFORMATION, AND OPERATIONAL

INSTRUCTIONS FOR COMPLIANCE WITH FCC RF EXPOSURE LIMITS ........................................22

6.2 FEDERAL COMMUNICATION COMMISSION REGULATIONS .........................................22

6.3 RF EXPOSURE COMPLIANCE, CONTROL GUIDELINES AND OPERATING

INSTRUCTIONS ...................................................................................................................................22

1.2 PRODUCT DESCRIPTION

The Crescend Technologies High Power UHF RF power amplifier is designed for paging and other
applications that use a single carrier constant envelope waveform. The amplifier is designed to be
powered from either an external +48 VDC source or an optional internal AC power supply. Model

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GA amplifiers cover the 406.1-420 MHz band without retuning. Model HA amplifiers cover the
450-454MHz, 456-462.5375MHz, 462.7375-467.5375MHz, 467.7375-470 -470MHz band without
retuning. Amplifier specifications are shown in Table 1-1. There are seven input ranges available
as shown in Table 1-2. Closed loop power control is used to maintain a constant output power
under varying voltage, signal input level, frequency and output load conditions. Several design
features work to protect the amplifier under adverse conditions.

The amplifier is designed to fit into 5.25 inches (3RU) of vertical 19-inch rack space. The front
panel includes LED indicators for monitoring status and alarm conditions. This information is also
accessible via a monitor connector on the rear of the amplifier. The fan assembly draws ambient
air in from the front and blows the air across the heat sink fins out the back of the amplifier.

NOTE: The manufacturer’s rated output power of this equipment (see Table 1-1) is specified

for single carrier operation using constant-envelope modulation. This equipment is
NOT designed for multiple-carrier operation, nor is it intended to be used with non­constant envelope modulation waveforms.

Table 1-1 Amplifier Specifications

Specification

Value

Instantaneous Bandwidth

406.1-420 MHz (GA models), 450-454MHz, 456-

462.5375MHz, 462.7375-467.5375MHz, 467.7375-470 ­470MHz (HA models)

Output Power Range

25 W - 250 W

Input Impedance

50 Ohms

Output Impedance

50 Ohms

Table 1-2 Amplifier Input Power Ranges

Input Power Designator Code

Input Power Range

Nominal Gain (250W Output)

R2GA, R2HA

0.2 - 0.5 W

28.5 dB

R5GA, R5HA

0.5 - 1 W

25.0 dB

1GA. 1HA

1 - 2 W

22.0 dB

2GA, 2HA

2- 5 W

18.5 dB

5GA, 5HA

5 - 10 W

15.0 dB

10GA, 10HA

10 - 20 W

12.0 dB

20GA, 20HA

30 - 40 W

8.5 dB

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2 INSTALLATION

2.1 INSTALLATION INSTRUCTIONS

The amplifier is designed for installation in a rack that permits access to the rear of the unit for
connection of RF and monitor/control cables, and DC power cables or AC line cord if the unit
incorporates the internal AC power supply option. The amplifier must have a minimum of 3 inches
of open space in front and to the rear of the chassis to allow adequate air flow and ventilation. If
installed in a closed or multi-unit rack, the operating ambient temperature within the rack
environment may be greater than the room ambient. The equipment installation must be
compatible with the +60°C maximum temperature rating of the amplifier. Caution should be
exercised when rack mounting the amplifier to avoid creation of a hazardous condition due to
uneven mechanical loading. Avoid “top-heavy” or cantilever installations which may cause the
equipment rack to become unbalanced. Consideration should be given to the connection of the
equipment to the AC or DC supply circuit and the effect that overloading of the circuits might have
on overcurrent protection and supply wiring. Consideration of the appropriate current rating (10A
for 110-125VAC operation, 20A for +48VDC operation) should be used in addressing this concern.
Caution should be exercised with supply connections which are not direct connections to the
branch circuit (e.g. use of power outlet strips). Reliable grounding of rack-mounted equipment
should always be maintained.

To install the amplifier, proceed as follows:

1. Mount the amplifier in equipment rack and secure in place.

2. Connect a properly sized 50 Ohm cable and load (antenna) to the RF OUT connector on
rear of amplifier.

3. Connect the transceiver/exciter output to RF IN connector on rear of amplifier.

4. If monitoring of PA is desired, connect alarm cable to MONITOR connector on rear of
amplifier module. See section 3 for more details about monitor pins.

5. Connect a ground cable to the rear panel stud of the amplifier. A UL Listed ground bonding
conductor assembly is recommended, such as Harger p/n UBC61411/4KIT5,
UBC61811/4KIT5, or UBC63211/4KIT5. These ground cable interfaces consist of Harger
p/n 6-6R1 ring tongue lugs crimped to various lengths of Harger p/n 6XLPE133G/YS #6
AWG ground cable.

6. If the unit is the 48 VDC version, measure the DC output voltage of the external power
supply. DC voltage should be +48 +/- 0.5VDC. Turn off the DC voltage.

NOTE:

 Make sure power supply DC is well filtered and well behaved with minimal voltage

overshoot.

 Keep DC cables as short as possible (recommend no greater than 2 feet) to

minimize inductive voltage transients.

 Size DC cables properly to handle the load current to minimize voltage drop during

times of transmission when current draw is highest.

WARNING:

 Turn off external primary DC power before connecting DC power cables.
 Connect positive primary power wire (+48VDC) to terminal marked +48VDC and

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negative primary power wire to GND terminal next to it on rear of amplifier.

7. Check your work before applying DC voltage to the system. Make certain all connections
are tight and the DC wires are going to the correct terminals.

8. If the unit has the optional internal AC power supply: Connect an unpowered AC cord to
AC plug on rear of amplifier.

9. Refer to Section 2.2 for initial start-up procedures.

2.2 INITIAL STARTUP

To perform the initial start-up, proceed as follows:

1. Check to ensure that all input and output cables are properly connected and tightened.

NOTE: Use high quality coaxial cable and connectors. Properly install all connectors for

reliability.

CAUTION: Before applying power, make sure that the input and output of the amplifier are

properly terminated in 50 ohms. Do not operate the amplifier without a load attached.
Refer to Table 1-2 for input power requirements. Excessive input power will damage
the amplifier.

NOTE: The output coaxial cable between the amplifier and antenna must be 50 Ohm cable

and adequately sized to handle the rated power level with additional stresses from
high VSWR taken into account. The shield of the 50 Ohm coaxial cable must be
connected to ground at the entrance of the building in which the equipment is installed.
This should be done in accordance with applicable national electrical installation
codes. In the U.S., this is required by Section 820.93 of the National Electrical Code,
ANSI/NFPA 70.

2. Apply 48 VDC from your power supply or AC mains power (depending on whether amplifier
has the optional internal AC power supply) to the amplifier with the supplied line cord. After
a short delay, the fans will power on. Check that all fans are running.

3. Visually check the indicators on the front of the amplifier and verify the following:

a. The PWR ON indicator (green) is on.
b. All other LED indicators (red and yellow) are off.

4. Set the external exciter power level so that it is within the specified input power range and
apply the RF signal to the amplifier input port. The amplifier will deliver nominally 250W
at the output connector. The green exciter drive status LED will illuminate when the RF
drive is detected. This LED is meant to give the user a general indication that the exciter
is active and is delivering output power when troubleshooting an alarm condition.
However, it does not indicate that the minimum input power level has necessarily been
reached.

5. Remove the RF input signal. The output power will drop to zero. Only the Power On
indicator will be illuminated. The amplifier is ready to use.

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3 OPERATING INFORMATION

3.1 INTRODUCTION

This section contains general amplifier operating information

3.2 STATUS INDICATORS AND MONITOR CONNECTOR

The amplifier status indicators and alarms are described in Table 3-1 and Table 3-2.

Table 3-1 High Power UHF Amplifier Status LED Indicators

STATUS LED

FUNCTION

PWR ON

Green LED. Illumination indicates unit is powered on

EXCITER DRIVE

Green LED. Illumination indicates RF input power has been applied

CHECK FAN

Red LED. Illumination indicates low fan speed or a locked rotor

HIGH TEMP

Red LED. Activates when the amplifier exceeds a safe operating temperature. Unit shuts down
until safe operating temperature returns

HIGH VSWR

Red LED. Activates when load VSWR > 3:1. Amplifier shuts down. Alarm active until RF input
removed and reapplied

HIGH INPUT

Yellow LED. Illumination indicates RF input power exceeds safe level (~125%) of rated input
power. Alarm active until RF input removed

LOW OUTPUT

Yellow LED. Can activate if power drops due to low gain or minimum specified input level is not
applied

Table 3-2 Monitor Connector Description

PIN NO

NAME

DESCRIPTION

1

POWER CTL

Output Power Level Control.
POWER CTL signal is pulled up internally to 10V and pulled down by POWER SET

potentiometer located on front panel. To ensure the full adjustment range of output
power from 250W to 25W with POWER CTL signal, make sure POWER SET is
turned fully clock wise (refer to section 3.5 for details).

Both POWER CTL analog input and POWER SET potentiometer can be disabled by
digital communication interface if either “PS=***\r” or “PM=***\r” command is sent to
the amplifier (refer to Table 3-7 in section 0 for details).

2

REV PWR

Reverse Power Voltage

3

GND

Ground Return

4

HI TEMP

Alarm - High Temperature Amplifier Shutdown

5

RXD

RS232 Interface Received Data

6

GND

Ground Return

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PIN NO

NAME

DESCRIPTION

7

HI INPUT

Alarm - RF Input Power Above Maximum Rating

8

CHECK FAN

Alarm - Low fan speed or locked rotor detected

9

PA FAULT

Alarm - Low Output Power, RF Input Power Above Maximum Rating, High
Temperature Amplifier Shutdown, High VSWR or No Power Supply Voltage

10

FWD PWR

Forward Power Voltage

11

HI VSWR

Alarm - High VSWR

12

RF DRIVE

Minimum RF Input Drive Indicator

13

TXD

RS232 Interface Transmitted Data

14

GND

NOT FOR EXTERNAL CONNECTION - DO NOT USE

15

LOW PWR

Alarm - Low Output Power

Figure 3-1 DSUB-15 Connector Pin Numbers