User's Manual

Copyright Crescend Technologies 6 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 CONDITION
APPROPRIATE
LOAD
Normal Operation: < 1 VDC
Alarm: > 8 VDC (up to Vcc)
> 10 kOhm,
< 100pF
ALARM
Summary
Alarm
Indicates when:
1. The output power is low,
or
2. VSWR cutback is
activated, or
3. Thermal cutback is
activated
Normal Operation: < 1 VDC
Alarm: 4 - 5 VDC
1.8 kOhm
between pin and
ground,
<500 pF
(TTL
compatible)
Normal Operation – pin not
connected.
CTRL
Partial
Power
Cutback
Used as a simple means of
cutting back output power
by a fixed amount (1-1.5
dB).
Cutback Mode – pin pulled
to ground. The output
power reduces by
approximately 1dB-1.5 dB.
<10 Ohm,
< 100pF
Normal Operation – pin not
connected.
SH/D
External
Power
Control
It is possible to reduce the
output power continuously
by up to 4 dB by connecting
a resistor between this pin
and ground.
Power Control Mode – pin
pulled to ground through
resistor.
Resistor value
0-50 kOhm,
<100 pF