Crescend Technologies VHFP15XXFF1 AMPLIFIER User Manual USERS MANUAL

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Document Description	USERS MANUAL
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Date Submitted	2007-08-23 00:00:00
Date Available	2007-10-12 00:00:00
Creation Date	2007-08-15 10:02:23
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Document Title	Microsoft Word - C5 Manual Rev B For P15 VHF FCC.doc
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Document Author:	Rita

INSTALLATION AND SERVICE
MANUAL
CONTINUOUS DUTY
VHF POWER AMPLIFIER
August 10, 2007 Rev B
Crescend Technologies
920 E. State Parkway
Schaumburg, IL 60173
Copyright Crescend Technologies
Tel:
Fax:
Email:
Web Site:
847 908 5400
847 908 5408
sales@CrescendTech.com
www.CrescendTech.com
Rev B
GENERAL DESCRIPTION
Warning! Changes or modifications not expressly approved by the party
responsible for compliance could void the users’ authority to operate the
equipment.
Compliance This device complies with part 15 of the FCC rules. Operation is
subject to the following two conditions: (1) This device may not cause harmful
interference, and (2) this device must accept any interference received, including
interference that may cause undesired operation.
1.1.
INTRODUCTION
This manual contains information and procedures for installation, operation, and general
maintenance of Crescend’s VHF Continuous Duty Power Amplifier.
1.2.
PRODUCT DESCRIPTION
The Crescend Technologies VHF RF power amplifiers are designed for trunking and
conventional repeater applications. Rack mountable and designed to accept a range of
input powers for a given rated output power, the amplifier covers a broad range of
frequencies. Closed loop power control is used to maintain a constant output power under
varying voltage, signal input, frequency and output load conditions. Several design features
work to protect the amplifier under adverse conditions.
The amplifier front panel includes status LED indicators for DC and Alarm conditions. RF
Input, RF Output, DC, summary alarm and power cutback connections are found on the
back of the amplifier. A fan is used to cool the amplifier.
Table 1-1. Amplifier Functional Specifications
Frequency Range:
See Table 1-2 (Range Set at Factory)
Operating Voltage:
+13.8 ±0.7 Vdc
Current Consumption:
See Table 1-2
Duty Cycle:
100%
Power Input:
See Table 1-2 (Range Set at Factory)
Power Output (Single Carrier Operation):
See Table 1-2 (Range Set at Factory)
Input Return Loss:
-10 dB (Maximum)
Spurious & Harmonics:
See Table 1-2
Input/Output Impedance:
50 Ohms (Nominal)
Load VSWR Tolerance:
VSWR Protected above 2.5:1 (Nominal)
Input/Output Connector:
Type N Female
Vertical Mounting:
7.0 in
Horizontal Mounting:
19.0 in
Weight:
10 lbs (4.6 kg) (Nominal)
Cooling Method:
Fan Forced Air Over Heat Sink
Operating Temp. Range:
-30°C to +60 °C
Storage & Transport:
-40 °C to +70 °C
Humidity:
80% at +40 °C (Non-Condensing)
Altitude:
Front Panel Display:
10,000 Feet (Maximum)
INDICATORS
Copyright Crescend Technologies
Rev B
DC ON (Green), LOW OUTPUT (Red),
HIGH VSWR (Red), OVER TEMP (Red)
SUMMARY ALARM
Summary of Low Output, High VSWR, Over
Temp Alarms
Alarm and Control Pins:
CONTROLS
CTRL(Partial Power Cutback)
SH/D (External Power Control)
Copyright Crescend Technologies
Rev B
Table 1-2. Frequency Ranges, Input/Output Power, Current, Spurious and Harmonics
Frequency
Range (MHz)
136-144 (DA)
144-152 (DB)
152-162 (EA)
162-174 (EB)
NOTES:
Input Power
Range (W)
Rated Output
Power (W)
Typ
Current
(A)
Max
Current
(A)
0.1-0.2
0.2-0.5
0.5-1
80 (P8)
16
19
100 (P10)
18
23
1-2
110 (P11)
22
25
2-5
150 (P15)
26
28
5-10
10-20
20-50
Manufacturer’s Rated Output Power of this Equipment is for
Single Carrier Operation.
Spurious
and
Harmonic
s (dBc)
<-65
<-65
<-65
<-67
All specifications above apply at +13.8 ± 0.1 VDC operating
voltage, ambient temperature of 25°C ± 5°C.
Copyright Crescend Technologies
Rev B
2.
INSTALLATION
2.1.
INTRODUCTION
This section contains installation recommendations, unpacking, inspection, and installation
instructions for the amplifier. Carefully read all the material in this section prior to
equipment unpacking or installation. Also read and review the operating procedures in
Section 3 prior to installing the equipment. It is important that the licensee perform these
tasks correctly and in good faith. If applicable, carefully read Parts 73 and 74 of the Federal
Communications Commission (FCC) rules to determine how they apply to your installation.
2.2.
ELECTRICAL SERVICE RECOMMENDATIONS
Crescend Technologies recommends that proper AC line conditioning and surge
suppression be provided on the primary AC input to the +13.8 VDC power source. All
electrical service should be installed in accordance with the National Electrical Code, any
applicable state or local codes, and good engineering practice. Special consideration
should be given to lightning protection of all systems in view of the vulnerability of most
transmitter sites to lightning. Lightning arrestors are recommended in the service entrance.
Straight, short ground runs are recommended. The electrical service must be well
grounded. Each amplifier should have its own circuit breaker.
2.3.
UNPACKING AND INSPECTION
This equipment has been operated, tested and calibrated at the factory. Only in the event
of severe mechanical shocks or other mistreatment should any substantial readjustment be
required. Carefully open the container(s) and remove the amplifier module(s). Retain all
packing material that can be reassembled in the event that the unit must be returned to the
factory.
CAUTION:
Exercise care in handling equipment during inspection to
prevent damage caused by rough or careless handling.
Visually inspect the amplifier module for damage that may have occurred during shipment.
Check for evidence of water damage, bent or warped chassis, loose screws or nuts, or
extraneous packing material in the connector or fans. Inspect the rear panel connector for
bent connector pins. If the equipment is damaged, a claim should be filed with the carrier
once the extent of any damage is assessed. We cannot stress too strongly the importance
of IMMEDIATE careful inspection of the equipment and the subsequent IMMEDIATE filing
of the necessary claims against the carrier if necessary. If possible, inspect the equipment
in the presence of the delivery person. If the equipment is damaged, the carrier is your first
area of recourse. If the equipment is damaged and must be returned to the factory, write or
phone for a return authorization. Crescend may not accept returns without a return
authorization. Claims for loss or damage may not be withheld from any payment to
Crescend, nor may any payment due be withheld pending the outcome thereof. WE
CANNOT GUARANTEE THE FREIGHT CARRIER’S PERFORMANCE.
2.4.
INSTALLATION INSTRUCTIONS
This amplifier is designed for installation in a rack that permits access to the rear of the rack
for connection of DC power, RF, and monitor/control cables. The amplifier must have a
minimum of 3 inches of open space to the rear to allow adequate ventilation.
To install the amplifier proceed as follows:
1. Install amplifier in equipment rack and secure in place.
2. Connect a 50 ohm antenna cable and load 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 “ALARM” pin on rear of
Copyright Crescend Technologies
Rev B
amplifier module. See section 2.5 for more details.
5. If limited output power control of PA is desired, connect control cable or
appropriate resistor to “SH/D” pin on rear of amplifier module. See section 2.5 for
more details.
6. If remote output power cutback of PA is desired, connect control cable to “CTRL”
pin on rear of amplifier module. See section 2.5 for more details.
7. Measure primary DC input voltage. DC input voltage should be +13.8 +/- 0.1VDC.
Turn off DC voltage.
WARNING: Turn off external primary DC power before connecting DC power cables.
8. Connect positive primary power wire (+13.8VDC) to terminal marked +13.8VDC
and negative primary power wire to GND terminal on rear of amplifier.
9. 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.
10. Refer to Section 3 for initial start-up procedures.
NOTE:
1. Make sure power supply DC is well filtered and well behaved with minimal
voltage overshoot.
2. Keep DC wires as short as possible to minimize inductance induced voltage
transients.
3. Size DC Wires properly to handle the load current to minimize voltage drop.
2.5.
AMPLIFIER SUMMARY ALARM AND POWER CUTBACK CONTROL
The summary alarm and cutback control connections are made through separate filtered
feedthrough connectors on the back of the amplifier.
Table 2-1. Summary Alarm and Cutback Control Connections
PIN
FUNCTION
DESCRIPTION
Indicates when:
1. The output power is low,
or
ALARM
Summary
Alarm
2. VSWR cutback is
activated, or
3. Thermal cutback is
activated
CTRL
SH/D
Partial
Power
Cutback
External
Power
Control
CONDITION
Normal Operation: < 1 VDC > 10 kOhm,
Alarm: > 8 VDC (up to Vcc) < 100pF
1.8 kOhm
between pin and
Normal Operation: < 1 VDC ground,
Alarm: 4 - 5 VDC
<500 pF
(TTL
compatible)
Normal Operation – pin not
Used as a simple means of connected.
cutting back output power
Cutback Mode – pin pulled
by a fixed amount (1-1.5
to ground. The output
dB).
power reduces by
approximately 1dB-1.5 dB.
It is possible to reduce the Normal Operation – pin not
output power continuously connected.
by up to 4 dB by connecting
a resistor between this pin Power Control Mode – pin
and ground.
pulled to ground through
resistor.
Copyright Crescend Technologies
APPROPRIATE
LOAD
<10 Ohm,
< 100pF
Resistor value
0-50 kOhm,
<100 pF
Rev B
3.
GENERAL OPERATING INFORMATION
3.1.
INTRODUCTION
This section contains operating instructions for the amplifier.
3.2.
STATUS INDICATORS
The function of the amplifier status indicators and is described in Table 3-1.
Table 3-1. Amplifier Status Indicators
STATUS LED
FUNCTION
DC ON
Green LED. Illumination indicates DC Power has been applied.
LOW OUTPUT
Red LED. Activates when the output power drops to approximately
70-85% of set output power.
HIGH VSWR
Red LED. Activates when load VSWR exceeds approximately
2.5:1.
HIGH TEMP
Red LED. Activates when the amplifier exceeds a safe operating
temperature.
3.3.
INITIAL STARTUP
To perform the initial start-up, proceed as follows:
Check to ensure that all input and output cables are properly connected and tightened.
Note: Use high quality coaxial cable and connectors. Properly install and solder all
connectors for reliability.
CAUTION:
NOTE:
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.
The output coaxial cable between the amplifier and the antenna
must be 50 ohm coaxial cable.
2. Apply DC power to the amplifier. Verify that the power supply measures 13.8 ± 0.1VDC.
The fan will come on immediately for a few seconds and then turn off.
3. Visually check the indicators on each amplifier module, and verify the following:
a.
The DC PWR ON indicator (green) should be on.
b.
All ALARM LED indicators (red) should be off.
4. Turn on external exciter/transceiver and apply RF input signal. The fan should turn on
after approximately 3 seconds.
5. Turn off RF input signal. The fan should continue running, but turn off after
approximately 6-12 seconds.
Copyright Crescend Technologies
Rev B
4.
PRINCIPLES OF OPERATION
4.1.
INTRODUCTION
This section contains principles of operation of the RF Power Amplifier.
4.2.
RF INPUT SIGNAL
The amplifiers are set at the factory to work over different input power ranges. The
available range of inputs ranges may be found in Table 1-2.
4.3.
RF OUTPUT LOAD
The load impedance should be as good as possible (VSWR <1.2:1) in the working band for
good power transfer to the load and maximum amplifier efficiency.
4.4.
FUNCTIONAL DESCRIPTION
The amplifier is a single channel CW amplifier that operates over the VHF frequency range.
The amplifier specifications are listed in Tables 1-1 and 1-2.
4.4.1.
MAIN RF PATH
The typical main RF path consists of an input attenuator, driver, splitter, final stage(s),
combiner, rf detectors and harmonic filter. The circuitry becomes active upon the
sensing of rf input power. This occurs when rf input reaches approximately 3 dB below
the low end of the input power range. This keeps standby current at a minimum (< 20
mA) when rf input is not present (or is below the turn on level).
4.4.2.
LOOP CONTROL
The loop control circuitry includes circuitry to works to maintain a constant output power
versus variations in DC voltage, rf input power, frequency and load. A coupled detector
at the output monitors the final RF output level and generates a DC voltage proportional
to the RF output level. This voltage is fed back to the controller. The circuitry compares
this voltage to a reference voltage and varies the gain of the amplifier to maintain a
constant output.
4.4.3.
VSWR PROTECTION
Reflected power is detected at the output of the amplifier and compared to forward
power. When reflected power reaches an equivalent VSWR of approximately 2.5:1, the
amplifier output is reduced to protect the finals and the front panel HIGH VSWR LED
activates. The higher the load VSWR, the more the output power is reduced.
4.4.4.
THERMAL PROTECTION
The heat sink temperature is monitored with a thermostat. When the heat sink
temperature reaches an unsafe level, the output power of the amplifier is reduced by
approximately 50%. This keeps the channel on the air while still providing some short
term protection until the customer can address the underlying cooling issue.
4.5.
AMPLIFIER COOLING
The amplifier is cooled with forced air over a large heat sink. It is important to keep a
minimum clearance of 3 inches behind the amplifier and allow the coolest air possible to
circulate through the fan.
Copyright Crescend Technologies
Rev B
5.
MAINTENANCE
5.1.
INTRODUCTION
This section contains periodic maintenance and performance test information for the
amplifier.
NOTE:
5.2.
Check your sales order and equipment warranty before attempting to service
or repair the unit. Do not break the seals on equipment under warranty or the
warranty will be null and void. Do not return equipment for warranty or repair
service until proper shipping instructions are received from the factory.
PERIODIC MAINTENANCE
Periodic maintenance requirements are listed in Table 5-1. Table 5-1 also lists the intervals
at which the tasks should be performed.
WARNING: Wear proper eye protection to avoid eye injury when using
compressed air.
Table 5-1. Periodic Maintenance
TASK
INTERVAL
30 Days
Clean Air Vents/Check
Fan
6 Months
Inspect Cables and
Connectors and General
Site Conditions
5.3.
ACTION
Inspect and clean per paragraph 5-3.
Verify fan is working properly.
Inspect signal and power cables for
frayed insulation and proper attachment.
Check RF connectors to make sure that
they are tight. Inspect the lightning
protection system and ground at the site.
CLEANING AIR INLETS/OUTLETS
The air inlets and outlets should be checked every 30 days and cleaned if necessary. If the
equipment is operated in a severe dust environment, it should be checked and cleaned
more often. If dust and dirt are allowed to accumulate, the cooling efficiency will be
diminished. Using either compressed air or a brush with soft bristles, loosen and remove
accumulated dust and dirt from the air inlet panels.
Check that the fan is running smoothly. A slow running or noisy fan may indicate an
imminent fan failure. Replace immediately with a similar to insure long term reliability.
Heat is one of the biggest factors in reducing the reliability of your amplifier. Make sure the
fan has access to cool and clean airflow within the rack.
Copyright Crescend Technologies
Rev B
5.4.
TEST EQUIPMENT REQUIRED FOR TEST
Test equipment required to test the amplifier performance is listed in Table 5-2. Equivalent
test equipment may be substituted for any item.
NOTE:
All RF test equipment must be calibrated to 0.05 dB resolution. Any deviation
from the nominal attenuation must be accounted for and factored into all
output readings.
Table 5-2. Test Equipment Required (or equivalent)
EQUIPMENT
MANUFACTURER
MODEL
Signal Generator (1)
H.P.
8657B
30 dB Attenuator, 200 Watt (1)
Tenuline
8322
DC power supply (1)
H.P
6673A
Spectrum Analyzer (1)
H.P.
8560E
Power Meter (1)
HP
E4418A
Power Meter (1)
HP
E4419A
Power Sensor (3)
HP
8481A
Pad (3)
Mini-Circuits
NAT-20
Coupler (2)
Narda
3020A
AR
30W1000M7
Coupler Load (1)
Lab Amplifier (1)
5.5.
PERFORMANCE TEST
Performance testing may be conducted to ensure that the amplifier system meets the
operational specifications listed in Tables 1-2 and 1-3. The test equipment required to
perform the testing is listed in Table 5-2 and the test setup is shown in Figure 5-1.
Signal
Generator
Lab
Amplifier
Watt Meter
Watt Meter
20
dB
20
dB
Coupler
Power
Supply
UUT
20
dB
Lo
ad
Coupler
Attenuator
30 dB
Spectrum
Analyzer
Figure 5-1. Amplifier Test Setup Diagram
Copyright Crescend Technologies
10
Rev B
6.
TROUBLESHOOTING
6.1.
INTRODUCTION
This section contains a list of potential problems and suggested actions to be taken. If the
suggested corrective action does not eliminate the problem, please contact your Crescend
factory for further instructions.
NOTE: Check your sales order and equipment warranty before attempting to
service or repair the unit. Do not break the seals on equipment under warranty
or the warranty will be null and void. Do not return equipment for warranty or
repair service until proper shipping instructions are received from the factory.
6.2.
TROUBLESHOOTING
Refer to Table 6-1 for troubleshooting suggestions. It has been found that in some cases it
may be necessary to power cycle an amplifier (turn DC power off and back on without RF
applied) to clear an alarm.
Table 6-1. Troubleshooting
INDICATOR
DC PWR ON
(Green)
LOW
OUTPUT
(Red)
LED STATUS
Unlit
On
On (all other
alarm LEDs
off)
OUTPUT POWER STATUS
No power
Set power
Less than set power
On (together
with HIGH
VSWR alarm
LED)
POSSIBLE CAUSE
No voltage at unit
Normal operation
Frequency is out of
range
The input power is
below the low end of
the rated input range
Power supply voltage
is too low
SUGGESTED ACTIONS
1. Check power supply voltage
1. No action required
1. Check frequency
Problem inside
amplifier
Output load VSWR is
much above 2.5:1
1.
1.
Check input power
1.
Check power supply voltage
at amplifier DC connector
during key-up
Send the unit back to factory
1.
2.
3.
HIGH VSWR
(Red)
On
Less than set power
Output load VSWR is
above 2.5:1
1.
2.
3.
OVER TEMP
(Red)
On
Less than set power
Fan is not rotating
1.
2.
3.
Power supply voltage
is too low causing
insufficient air flow
Operating
temperature of
amplifier is exceeding
safe level. Note:
When unit cools, LED
turns off and output
returns to rated power
1.
2.
3.
4.
Copyright Crescend Technologies
11
Turn off amplifier (or remove
RF input)
Check output connections
and cables for integrity and
tightness
Check antenna, combiner,
etc. for proper return loss
Turn off amplifier (or remove
RF input)
Check output connections
and cables for integrity and
tightness
Check antenna, combiner,
etc. for proper return loss
Check if +13 VDC is present
on the FAN feedthrough pin
when rf input present (after
3 sec turn on delay)
Check if anything is
physically stopping rotation
If fan has failed, replace fan
with same or similar fan
Check power supply voltage
Make sure that air access to
front and rear of unit is
unimpeded
Verify that air vents are
clear of dust and dirt and
that fan(s) are operating
properly. Replace fan if
necessary
Check ambient temperature
(not to exceed spec - see
Table 1-2)
Rev B
6.3.
RETURN FOR SERVICE PROCEDURES
When returning products to Crescend, the following procedures will ensure optimum
response.
6.3.1. OBTAINING AN RMA
A Return Material Authorization (RMA) number must be obtained prior to returning
equipment to the factory for service. Please contact our Customer Service Department
at 800-872-6233 to obtain this number. Failure to obtain this RMA number may result in
considerable delays in receiving repair service.
6.3.2. REPACKAGING FOR SHIPMENT
To ensure safe shipment of the amplifier, it is recommended to use the packaging
designed for the amplifier. The original packaging material is reusable. If it is not
available, contact Crescend’s Customer Service Department for packing materials and
information.
Copyright Crescend Technologies
12
Rev B

---

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