Crescend Technologies P8XXL1 AMPLIFIER User Manual
Crescend Technologies LLC AMPLIFIER Users Manual
Users Manual
P8XXJK1 and P8XXL1
Power Amplifier User’s Manual
1. General Information.
Power Amplifier (PA) is the C-class unit. It is intended for amplification of single carrier phase
(frequency) modulated (manipulated) narrowband signals.
Working frequency range lies between 764 MHz and 870 MHz for JK unit (P8XXJK1) and
between 890 MHz and 942 MHz for LW unit (P8XXL1). Code “xx” shows the input power range:
Code: R1 R2 R5 1 2 5 10 20
Range, W: 0.1-0.2 0.2-0.5 0.5-1.0 1.0-2.0 2.0-5.0 5.0-10 10-20 20-50
In the normal operating mode the minimum output power is 80 W for JK and 80 W for L unit.
Input VSWR is not greater than 1.7:1.
PA meets all FCC requirements to harmonic and spurious levels.
The nominal power supply voltage is 13.8VDC.
DC current consumption does not exceed 24A at 13.8V
Working ambient temperature range lies from -30ºC to +60ºC.
Input and output power levels are set up in the factory. Customer has an opportunity to reduce
the output power, adjusting the special trimmer resistor in the unit, or picking up the value of outer
resistor, connected to PA control pin.
PA has automatic power control loop that provides the stability of output power during the
normal operation and all necessary changes of power in the case of load mismatch or unit
overheating.
PA is intended for rack mounting in the standard 19” cabinet. The front panel is 7” high. The
deepness of unit does not exceed 5”.
Four LED at the front panel indicate the status of unit operation.
The hole in the side wall gives an access to the trimmer resistor, which allows reducing the
output power against the set value.
There are two N connectors at the back of chassis.
There is power filtering DC connector at the back of chassis with # 6-32 screws.
There are 3 filters at the back of chassis that bring alarming signal, as well signals for the
outside power control.
Two fans at the back side of unit perform the forced air cooling. Fans start rotating, when RF
signal comes to the unit input.
2. Installation Guide.
2.1. Unit installation shall provide a proper air access to the unit; no obstacle for air is allowed
closer than 3” from fans.
2.2. Copper wires # 10 AWG shall be use in DC power line. Wires shall be crimped to ring
terminals.
3. Operation Guide
3.1. Power supply voltage shall be in the range 13.8 V + 1.0 V.
3.2. The input power inside the working frequency range shall be within the listed above limits.
It is prohibit applying any RF signal out of the working frequency range with a power, greater
than 10% of the minimum rated one.
3.3. Green LED “DC ON” is on, when DC voltage is applied to the unit.
3.4. Red LED “LOW POWER” is on, when the output power drops below 80% - 85% of set level.
In majority of cases it warns about of inside problem. However, the output power may fail due
to high load VSWR (in that case LED tells that the power decrease is stronger, then it is
needed for VSWR protection).
3.5. Red LED “HIGH VSWR” is on, when the load VSWR exceeds 2.4 – 3. The output power is
reduced.
3.6. Red LED “HIGH TEMP” is on, when the heatsink temperature is over +85˚C. Then the unit
operates with output power, reduced to about 75% of rated one. Fans are running continuously,
no matter, is RF drive applied or not.
3.7. Voltage at filter “ALARM” is about 9.5V during the normal unit operation and drops to less
than 0.5V, when any of mentioned above red LED goes on. If 1.8 kOhm resistor is connected
between this filter and the ground, TTL compatible output is created.
3.8. It is possible to significantly reduce the output power, pulling filter “SH/D” to the ground.
However, it is possible to change the output power smoothly by a trimmer resistor (50 kOhm is
the recommended value of it), connected between this pin and the ground.
3.9. The output power drops to about 75% of rated level, if the filter “CTRL” is pulled to the
ground.