CDX2000 / 13.56 MHz & 400 kHz Manual
© 2006 Comdel, Inc.
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In the 13.56 MHz amplifier the forward and reflected signals are fed into the OCB where they are linearized.
They are then fed to the CDX controller where they are reproduced to the remote interface connector and
displayed on the front panel. The reflected power signal is only present when the generator is driving a load
that is not purely resistive, or not 50 ohms. This signal is also used to drive the OCB VSWR shutdown
circuitry.
In the 400 kHz amplifier the forward and reflected signals are linearized and output to the CDX controller
where they are displayed on the front panel and buffered for the remote interface connector.
H. CDX
Controller
The CDX controller is comprised of four PC boards mounted to the left side of the front panel:
1. CDX INTERFACE PCB
The function of the CDX Interface PCB (Figure FA0614RX) is to condition all of the analog and digital
inputs and outputs for the CX Microcontroller. This PCB board also provides the protection control
circuitry to limit forward power in cases of high PA current or high PA RF voltage. This protection
function is handled by U2. The reflected power protection circuit for the LF PA is located at U1D.
2. CX MICROCONTROLLER PCB
This PCB (Figure FA0604RX), mounted under the CX INTERFACE PCB, contains a 16 bit
microprocessor, memory, digital I/O, and analog I/O to control and monitor all activities of the CDX2000.
If for any reason the program is terminated or gets lost, the watchdog timer U6 automatically restarts the
system. U6 also monitors VCC for low voltage conditions. If VCC drops below 4.5V, the system is shut
down via uP reset line, U1-71.
If the optional RS-232 serial port is utilized, U7 and associated components supplies the interface.
U14 provides the 5V or 10V reference for the A/D (U11) and D/A (U13) converters.
3. SOFTKEY INPUT INTERFACE PCB
This PCB (Figure FA0605RX) is mounted under the CX MICROCONTROLLER PCB and contains the
softkey sense pads and buffer circuitry to interface all front panel user interface to the CX Microcontroller.
4. 20 x 2 CHARACTER ALPHA NUMERIC FLORESCENT DISPLAY PCB
This PCB, also mounted under the CX MICROCONTROLLER PCB, provides the display, high voltage
power supply, drive circuitry, and microprocessor to interface the 20 x 2 character display to the CX
Microcontroller data bus.
I.
CDX Autotune Parameters
The parameter settings in the CDX2000 software V3.09 are adjustable via the dip switch settings on the
microcontroller board. The settings are only recognized and adjusted during initialization. The settings are
displayed for one second during the software initialization routine. The frequency tuning span is 380-420 kHz.
The minimum step size is 10Hz. The following parameters can be varied, with the factory default values in
BOLD type:
1. Gain: The gain is an arbitrary number that is multiplied by an error signal (proportional to rfl/fwd) to
determine the size of the frequency step adjustment. By setting the value of dip switch positions 1&2 the
gain number is varied as follows:
0
15
1
20
2
25
3
30
