AR 10012510, Operating And Service Manual

Page: 41 / 72

Model 200T8G18A/250T8G18
Rev D 23
A small sample program that can send commands and receive the strings returned by the TWTA is included
in section 5.5. It is written in Hewlett-Packard's "Rocky Mountain" BASIC. The program assumes that the
IEEE-488 bus is at address 7 and that the address of the TWTA is 01.
Remote operation is determined by the application (software) program in the system controller. This
application program will aid the user in generating the Command Codes and displaying/monitoring the Status
Codes. Consult the application program users instructions for Remote operation procedure.
The application program should issue only one string at a time. After each functional command is issued the
status should be checked to ensure that the command has been properly executed. The application program
should allow sufficient time for the function to be completed before checking the status.
The application program should facilitate checking the status just prior to issuing a command - since the
status could have been changed by a fault condition of the amplifier or by operator activation of the amplifier.
Periodic checking of the status is also recommended.
3.9 PULSED OPERATION
This amplifier is provided with a rear-panel BNC connector which can be used for pulsing the beam of the
TWT and hence the RF output. As compared with providing a pulsed RF input, pulsing the beam of the TWT
offer low noise between pulses. It also offers reduced prime power consumption for low duty factor pulsing,
since the beam current is off most of the time.
In the CW mode (not pulse mode) the amplifier pulse input is pulled high to permit CW operation with no
external jumpers. To set the amplifier for pulse or CW operation, enter the setup menu and push MORE until
reaching the last setup screen, which says
amplifier is set to... Push SET to achieve the mode of operation
desired.
In the pulse mode, the impedance of the pulse gate input is approximately 50 ohms. The logic is positive; a
logic high (greater than +2V) turns the pulse on.
Two modes are selectable from the front panel menu:
•
CW
•
Pulse
In CW mode it is expected that the user will NOT connect a pulse generator to the pulse input.
CAUTION:
Do not connect a pulse generator to the pulse gate input when operating in
the CW mode.
When switching from PULSE mode to CW mode, a warning is displayed to alert the user to disconnect the
pulse generator. When disconnected, press SET again to set to CW mode.
If no generator is connected and the CW mode is selected, the unit will operate in the CW mode and the
amplifier will amplify the RF input signal, ie the unit will operate as a unit without pulsing.