Rev D
5
2. OPERATING INSTRUCTIONS
2.1 GENERAL
Operation of the Model 250S1G6 broadband amplifier is quite simple. The amplifier’s input signal, whether
swept or fixed in frequency, is fed into the jack marked
RF INPUT,
and the amplifier’s output signal is taken
from the jack labeled
RF OUTPUT
. The unit is turned on by activating the front panel
POWER
switch. In
the event of a major malfunction, protection is provided by a circuit breaker located on the unit’s rear panel.
CAUTION:
The Model 250S1G6 Amplifier is
typically
not critical in regard to source
and load Voltage Standing Wave Ratio (VSWR) and will remain
unconditionally stable with any magnitude and phase of source and load
VSWR.
However, placing the amplifier in the operate mode without a load
connected to the output connector is not recommended
. It has also been
designed to withstand, without damage, RF input power levels up to
twenty (20) times its rated input of 1mW. However, signal levels higher
than 20mW or transients with high peak voltages can damage the
amplifier. Also, accidental connection of the Model 250S1G6’s output to
its input (either through direct connection or parasitic feedback paths)
will cause oscillations that may permanently damage the unit’s input
transistors.
The 250S1G6 Amplifier is protected from input overdrive by an automatic level control circuit which will
limit the maximum RF level to the first gain stage (U2) of the RF Amplifier to approximately 0 dBm.
NOTE:
The amplifier requires 30 minutes of warm-up time to avoid any gain or power drift.
The 250S1G6 RF power transistors are protected from over temperature by sensing the chassis temperature
near the RF output transistors. In the event of a cooling fan failure or an airflow blockage, the DC voltage will
be removed from the RF stages, when the chassis temperature reaches approximately 70°C.
Normal operation can be resumed after the chassis temperature drops below 70° C.
2.2 CONTROL AND INDICATOR FUNCTIONS
The Model 250S1G6’s front panel is shown in Figure 2-1; the unit’s rear panel features are detailed in
Figure 2-2.
2.2.1
Keylock Switch
The Keylock Switch is provided for protection from unauthorized use or unexpected remote control of the
amplifier. The amplifier can only be turned on locally when the Keylock Switch is in the
LOCAL
position.
Likewise, the unit can only be turned on or controlled remotely when the Keylock Switch is in the
REMOTE
position. Placing the Keylock Switch in the
INHIBIT
position places the amplifier in the off mode and
prohibits any control of the amplifier.
