Comdel CPS-500AS User manual

FP0113RK
10/31/97 G.E.C.
CPS-500AS
13.56MHz RF GENERATOR
Operator’s Manual
Copyright © 2003 by Comdel, Inc.
The information contained in this manual is proprietary to Comdel, Inc. and is protected by copyright and trademark laws.
You may not modify, copy, reproduce, republish, post, transmit, or distribute in any way any material from this manual except as may be
expressly permitted in writing by Comdel, Inc.
Comdel, Inc. •11 Kondelin Road, Gloucester, MA 01930• Phone: [phone] •www.comdel.com

Table of Contents
I. Safety Information...................................................................1
II. Description...............................................................................4
III. Unpacking and Inspection.......................................................4
IV. Maintenance............................................................................4
V. Preparation For Use................................................................5
A. Power Requirements
B. Cooling Requirements
C. Controls and Indicators
VI. Operating Instructions.............................................................5
A. Local Operation
B. Remote Operation
C. J1 Connector Pin Designations
D. RF Keying
E. Forward and Reflected Power Monitoring
VII.Theory of Operation................................................................6
A. DC Power Supply
B. Oscillator Control Board
C. Driver
D. Power Amplifier
E. Low Pass Filter
F. Directional Coupler
VIII. Adjustments and Calibration.................................................8
A. Over Voltage / Over Current Adjustment
B. VSWR Adjustment
C. Thermal Set
D. Forward RF Power Calibration
E. Reflected RF Power Calibration
F. Enable
G. Interlocks
IX. Figures
FP0113RX CPS 500AS / 13.56 MHz Block Diagram
FP0113RX CPS 500AS Control Drawing
FA0401RX Oscillator Control Board
FA0637RX Integrated Meter Board

1
NOTE: Before installing equipment, carefully read and familiarize yourself with the entire operations
manual. Observe and obey all WARNING and CAUTION notes provided.
I. Safety Information
Warning Label and Safety Marking Explanations:
The following symbols and terms may be found on an instrument or used in this manual.
The CE mark indicates compliance with all currentlyapplicable directives and standards.
This label indicates a general warning or caution condition.
This symbol indicates the presence of high voltages in or around the unit.
This symbol indicates that the component or circuit is short circuit protected.
This symbol indicates the presence of RF energy in or around the unit.
This symbol indicates a protective earth ground connecting point.
This label indicates a
presence of high voltage in or
around the equipment, which
may cause sever injury or
death. All appropriate
precautions should be
observed when installing,
operating or servicing this
equipment.
This label indicates the presence
of Radio Frequency energy in
and around the equipment, which
may cause burns or other
injuries. All appropriate
precautions should be followed
when installing, operating or
servicing this equipment.

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The WARNINGheading used in this manual explains dangers that might result in personal injury or death. Always
read the associated information very carefully before performing the indicated procedure.
The CAUTION heading used in this manual explains hazards that coulddamage the unit. Such damage may
invalidate the warranty.
MUST–This word is understood to indicate a mandatory condition.
HIGH VOLTAGE–Voltages greater than 50 volts DC or 25volts AC and known to cause death or serious injury if
contacted.
SERVICE–Any operation of maintenance, repair, calibration or similar activity other than the normal operation of
the unit.
QUALIFIED SERVICE TECHNICIAN, QUALIFIED ELECTRICIAN, QUALIFIED PERSONELL These terms indicate
persons specifically trained to install, service or other wise handle electronic equipment of the character and hazard
potential of this unit.
End User Labeling
The system installer should obtain and apply all appropriate safety and warning labels required by the end user’s
local fire department jurisdiction and Occupational Health and Safety Administration over and above those supplied
by the generator manufacturer.
Read And Understand This Section Fully Before Installing or Operating This Equipment.
WARNING: This equipment must be installed, operated and serviced only by trained, qualified persons.
General Safety Requirements
•WARNING: Hazardous Voltages and RF voltages are present inside this unit, which may cause injury or death.
To prevent electricalshock and or RF burns, never operate this equipment with the covers removed. Never
operate without an appropriate cable connected between the RF output connector on the rear panel and the
load.
•CAUTION: There are no user or operator serviceable parts inside this equipment. Refer all service to a
qualified service technician.
•This equipment must be bonded to Protective Earth (safety ground) prior to operating the unit. Safety ground
connection must be made at the unit’s rear panel designated 1/4”-20 threaded ground stud. The ground wire
should be a #14 awg or equivalent (minimum) green/yellow lead.
•There is no reset required to restore operation after a shutdown due to over-temperature. If the cause of an
overtemp shutdown is to be investigated, primary power should be removed from unit or RF will restart as soon
as heat sinks cool below 75º C.

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•HEAVY OBJECT CAUTION: A heavy object caution exists for equipment weighing more that
51 lbs or 23 kg. Use lifting aids to install unit, such as chain lifts or hooks and straps, attached to the four
handles at the sides and front of unit. Guide unit into final location using care to keep hands and body parts
clear of unit.
CE Mark Specific Safety Requirements
•This equipment meets all applicable safety directives (as specified in prEN50178) required to qualify for the
application of the CE marking.
•This equipment must be installed in accordance with the applicable requirements, or prEN50178 and EN60204-1 /
IEC-204-1.
•This equipment is qualified to operate at Pollution Degree II and Insulation Category II.
•The installation of this equipment must assure that the AC power input connector (UL/CSA) is not accessible to
the user/operator. Access may be gained only by a qualified service technician. AC Mains connector
installation must be in accordance with local requirements.
•This unit provides appropriate separation between all interface, mains and output circuits in accordance with
5.2.18 of prEN50178.

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II. Description / Specification
The CPS-500AS is a 500 watt R.F. generator operating at a fixed frequency of 13.56 MHz. The generator is designed
to produce maximum power into a 50 Ωload.
NOTE: This generator has been customized to run at 100w, but is capable of operation up to 500 watts.
The primary features of the CPS-500AS are a solid-state design, small physical size and the ability to withstand large
changes in load impedance without failure. The CPS-500AS can be examined as two separate sections, the DC Power
Supply and the RF section.
The DC Power supply provides +40 VDC and +/-15 VDC required to operate and control the RF Section. The DC
Power Supply (as supplied) is powered by 120 VAC single phase 50-60Hz with line current of 6A. This supply can be
operated on several line voltages by changing primary transformer taps, as explained in Section 2.3.
The RF Section operates on +40 VDC and +/-15 VDC and generates 500 watts into 50Ω. There are five basic parts in
this section. They are: oscillator and control circuitry, driver, power amplifier, low-pass filter and directional coupler.
The CPS-500AS RF Generator is designedfor long life and low maintenance operation.
III. Unpacking and Inspection
1. Carefully unpack the unit and inspect for any obvious signs of physical damage that might have
occurred during shipment. Notify the shipping agent of any damage immediately.
2. Check the outside of the unit for missing or loose mounting screws or broken parts.
3. If there is shipping damage or the unit fails to operate properly upon receipt, report damage to the
carrier and Comdel immediately.
CAUTION: Breaking the seal or removing the warranty decal from this unit will void the warranty. If internal
damage is suspected, contact factory for assistance.
IV. Maintenance
The CPS-500AS is designed to run unattended for long periods of time. Should service be required, the
system is modularly designed for quick repair. The whole RF section could be replaced in less than thirty
minutes.
After a time, scale may build up on the inside of the cooling tubes. This could greatly reduce the cooling
capacity of the system. It is recommended that the system be flushed with a descaling agent. A cleaning
agent that does not damage copper, brass, stainless-steel and nylon tubing should be chosen.

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V. Preparation for Use
A. Power Requirements
The CPS-500AS RF Generator is designed to operate at several different line voltages. Unless other wise
specified the generator is configured to operate at 115VAC at the factory.
B. Cooling Requirements
The CPS-500AS is forced air-cooled by two fans. All air inlets and exits to the generator should be
unobstructed. The ambient air temperature should not exceed 25º C.
C. Controls And Indicators
1. Circuit Breaker -Interrupts power to the primary of the transformer.
2. Remote/Local Switch -When the switch is in the “Remote” position, the generator will be controlled by
the signal fed into Connector J1. When the switch is in the “Local” position, the generator will be
controlled by the power control knob on the front panel.
3. Power Control -Local power control is accomplished by means of a ten turn potentiometer. Full
counter-clockwise is 0 watts output.
4. Power On Indicator -This indicator lights when circuit breaker is in the ON position.
5. Over-temp Indicator -This indicator turns on when an over-temperature situation occurs.
VI. Operating Instructions
Before the AC power is connected, make sure the local power control potentiometer is turned fully counter-clockwise
and the local/remote switch is in the LOCAL position. On Connector J1, Pin 11 should be connected to Pin 12 to RF
enable. Pin 4 of J1 mustbe returned to Pin 9.
A. Local Control
Local Control is accomplished by turning power control pot clockwise to increase the output power. When
the pot is in its full clockwise position, power output will be 500W +10% -0%.
B. Remote Control
Operating the CPS-500AS in the Remote condition requires a 0 to +10 VDC power supply connected
positive to Pin 5 J1 and negative to Pin 6 J1.

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C. J1 Connector Pin Designations
Pin 1 NC
Pin 2 Reflected Power Ind. 10 VDC for 500W *
Pin 3 Forward Power Ind. 10 VDC for 500W *
Pin 4 RF Enable (Ground to operate)
Pin 5 Power Control 10 VDC for 500W *
Pin 6 Ground (Remote Power Control Return)
Pin 7 RF Enabled +5 VDC shows RF Enabled
Pin 8 Overtemp Indicator (Pulled to ground on temperature rise)
Pin 9 RF Enable return
Pin 10 NC
Pin 11 Interlock -connection to Pin 12 enables system
Pin 12 Interlock -connection to Pin 11 enables system
Pin 13 NC
* Other input and output voltages are available. Consult factory for other options.
D. RF Keying (Pulsing)
Operating the CPS-500AS in the Remote Pulse condition requires a pulse whose amplitude is proportional to
output pulse power (10V = 500W) and whose duty cycle and rep rate are as required in the output power
wave form. Minimum pulse width is 50 microseconds, max rep rate is 5 KHz. The pulse supply is connected
with Pin 5 J1 as pulse input and Pin 6 J1 as the return.
E. Forward and Reflected Power Monitoring
Forward and Reflected Power Monitoring access is gained through Pins 3 and 2 (J1). Pin 3 isforward and
Pin 2 is reflected. These provide a DC voltage proportional to power.
VII. Theory of Operation
The CPS-500AS is a source of radio frequency energy for use in RF plasma applications. It consists of six stages and
associated control systems and monitoring circuits as shown in the CPS-500AS functional block diagram
(FP0113RX).
The radio frequency signal is generated in the oscillator and amplified by the driver. From the driver, the signal is fed
into the power amplifier. The signals from the power amplifier are then passed through a low-pass filter. From the
filter, the signal travels through the directional coupler to the power output connector.
A. DC Power Supply
The DC Supply consists of a transformer, two full wave rectifiers and two low-pass filters. The output of
this stage is:
140 VDC -45 VDC Unloaded
33 VDC min Loaded (25 A max)
1+/-15 VDC Regulated

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B. Oscillator Control Board
The CPS-500AS oscillator module has four parts: The clock oscillator, three stages of gain and gain control
circuitry. The clock oscillator is a purchased standard TTL output device. This circuit is utilized because of
its frequency stability and immunity to fluctuations in both temperature and output load impedance.
The gain control circuitry has several functions: it smoothes output control, stabilizes output power against
variations in the power line or load and pulses the oscillator under high VSWR conditions. This is
accomplished by using a LF356 op-amp connected as a comparator. The inverting terminal is related to the
forward power while the non-inverting terminal supplies the DC reference voltage. Also connected to the
non-inverting terminal is the reverse power shut down, which is controlled by the pull down transistor
whose signal is supplied by the reflected power detector.
Typical Specifications
(OCB)
Output load impedance 50 ohms
Output RF power level 1 watt (max)
Input Voltages Pin 5 -15 V min
Pin 9 +15 V min
Input Currents Pin 5 250mA
Pin 9 250mA
Reflected power limit Internally set to 100W reflected
C. Driver
The driver is a Class “C”, two stage amplifier with feedback. The first transistor operates with approximately
1 watt input from the oscillator and amplifies this to 10 watts. The circuitry between the first and second
transistor contains more impedance matching and a loss section for stability and isolation. The output of
this stage is 25 watts. There are no adjustments or tuning required for this stage.
Typical Specifications
(Driver)
Gain 14dB
Input power 1 watt
Output RF power 25 watts
Input impedance 50 Ohms
Output load impedance 50 Ohms
Collector voltage (at full output) 33 VDC
Collector currant (at full output) 4 ADC
D. Power Amplifier
The power amplifier stage utilizes four transistors arranged into two pairs of push-pull Class “C” amplifiers.
The input requirements of this stage are met by the 25 watts into 50Ωproduced by the driver stage. At the
input there is an impedance matching network, a hybrid splitter which then fees into two push-pull
transistor driving transformers. Each of these transformers drives the bases of two transistors. These
transistors are operated common emitter with feedback. Each collector signal is coupled together by means
of a push-pull combiner. The signals from each ofthese push-pull combiners are then added again with a
hybrid combiner. The output of this stage is typically 550W into 25Ω.

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Typical Specifications
Gain 12 dB (min)
Input power 25 watts (typical)
Output power 550 watts
Input impedance 50 ohms
Output load impedance 25 ohms
Collector voltage (at full output) 33 VDC
Collector current (at full output) 22 ADC
E. Low Pass Filter
The low-pass filter is designed to filter the higher order harmonics and leave a low distortion carrier signal.
This stage also matches the terminating impedance of the amplifier 25 ohms to 50 ohms load impedance. The
filter is a “T” configuration.
F. Directional Coupler
The directional coupler stage produces voltages, which are proportional to the square of both the forward
and reflected power. This stage utilizes inductive (current) and capacitive (voltage) taps to determine the
forward and reflected power. This stage is factory fitted and needs no further adjustment.
VIII. Adjustments and Calibration
The only adjustments required on the CPS-500AS are made to the monitoring and transistor protection circuitry. All
of these adjustments have been performed at the factory and generally will never have to be reset.
A. Over Voltage / Over Current Adjustment
The OV OC potentiometer adjustments are located on the integrated meter assembly FA0637RX. These
adjustments should be altered only when the generator is operating into a 50 Ωreal load. The procedure for
adjustment is as follows:
1. See instructions “Operating into 50Ω”
2. Set generator at maximum output power
3. Turn all adjustmentsto their maximum counter-clockwise limit
4. Set input ac voltage to low line. Then start turning current limit adjustment R21 clockwise until
output power drips to 550W.
5. Set input ac voltage to high line. Then turn the voltage limit adjustment R22 clockwise until
output power just starts to drop. The output power should be 550 watts.
B. VSWR Adjustment
The VSWR set is located in the oscillator module and is adjusted by R1. See FA0401RE. Under high VSWR
conditions, Q6 is biased on and pulls the reference voltage low. When this circuitry is activated, the unit
will go into a pulsed operation until the high VSWR condition is eliminated. The oscillator module is set to
go into limit operation when there is 100W reflected. The procedure for adjustment is as follows.

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1. See operating instructions, Section 3.
2. Adjust generator so that it produces 100W into 50Ω.
3. Turn off line power.
4. Remove coaxial cable on the load side of the watt meter.
5. Turn on line power.
6. Turn adjustment (R39) until the reflected power indication on the watt meter just
starts to drop.
C. Thermal Set
The thermal set on the CPS-500AS is pre-set to operate at a power amplifier block temperature of 80º C. The
temperature sensor is mounted on the power amplifier. This sensor pulls down to ground and turns
generator off when set temperature is exceeded.
D. Forward RF Power Calibration
1. Connect unit to RF dummy load with an accurate (customer’s standard) external power meter
to monitor the RF output power.
2. With RF disabled, measure the local power control pot voltage at “SETPT” test point on
OSCILLATOR CONTROL BOARD with the DVM and set for 10 VDC.
3. Enable RF and adjust FORWARD OUT CALIBRATION pot R34 on the Oscillator Control
Board on right side of unit until the forward readback voltage out of the rear panel connector,
Pin 3 reads 10V with respect to ground.
4. Adjust pot located behind front panel FORWARD meter so that meter reads 500W.
5. Adjust ACTUAL CALIBRATION POT R44 on the Oscillator Control Board until external
power meter reads 500W.
E. Reflected RF Power Calibration
1. Disconnect RF cable from RF output connector.
2. Set power for 100 watts and enable RF power into the open load.
3. Adjust REFLECTED CAL pot R67 on Oscillator Control Board until the voltage at Pin 2 or rear
panel connector matches the voltage on Pin 3.
4. Adjust REFLECTED METER pot located behind frontpanel meter until the reflected meter
reading matches the forward meter reading.
F. Enable
Pin 4 on J1 is provided for remote enable or disable. A ground applied to Pin 4 enables the RF output.
G. Interlocks
An internal interlock loop is provided. Pin 11 must be tied to Pin 12 through the external interlock loop in
order to enable the generator. Also, an RF Safety Interlock has been installed near the RF connector, for
added safety.