Specifications

Alpha 9500 HF Linear Amplifier Operating Manual Alpha Radio Products
Amplifier Components Product Release 1
DOCNUMBER 9500
Document Issue 1, Revision 7
Page 2–6 June 2009
22
2
The time for the master to cycle through one round of communications
with all slaves and perform its own tasks defines the natural “heartbeat”
for the amplifier. This heartbeat is 10 ms, which is faster than the response
time of the human eye.
You can upgrade the master firmware via a serial or USB connection to a
Microsoft Windows PC. For information, see
8, “Maintaining and
Upgrading the Amplifier,” page 8–1.
2.7 Master-Control Board
The master-control board is the heart of the amplifier. It is based around
a PIC microcontroller, the master of the I2C bus. This microcontroller
communicates with each controller on the other boards in the amplifier. It
is used to monitor all the critical voltages and currents in the amplifier, as
well as the input power and output forward and reflected power. It uses
these converted values to control the amplifier’s operation and to send
data to the front panel, so that the correct LEDs are lit and the stepper
motors move to the correct positions. A standard 9-pin RS-232 serial port
is provided for control and monitoring and is found on the back of the
ALPHA 9500. A USB port is also provided. Either port may be used, but
only one may be active at any one time.
The amplifier automatically senses when a PC is attached to the USB port,
and uses that port. If nothing is connected to the USB, the amplifier
automatically switches back to the RS-232 serial port.
2.8 Output-Tank Circuit
The output-tank circuit provides reliable high-efficiency, low-distortion
performance in a very compact volume. The basic topology is “pi-L”,
which provides harmonic attenuation adequate to meet the requirements
of all countries globally that permit power outputs of 1500 W.
Band switching is under automatic control, accomplished by a 4-wafer
band switch. These wafers are used as multifunction tap selectors, which
simultaneously select band taps on the inductors and include varying
amounts of capacitance to provide band spread on the tune and load
capacitors. The wafers are in the RF tank area. The band-switch position
is controlled by a stepper motor in the front subchassis.