INSTRUCTIONS MODEL AV-1022-C-AS4 5 V, 1 MHz LAB PULSE-DELAY GENERATOR SERIAL NUMBER: ____________ __________________________________________________________________ ii WARRANTY Avtech Electrosystems Ltd. warrants products of its manufacture to be f ree from defects in material and workmanship under conditions of normal use. If, within one year after delivery to the original owner, and after prepaid return by the origina l owner, this Avtech product is found to be defective, Avtech shall at its option repair or replace said defective item. This warranty does not apply to units which have been d issembled, modified or subjected to conditions exceeding the applicable specificat ions or ratings. This warranty is the extent of the obligation assumed by Avtech with re spect to this product and no other warranty or guarantee is either expressed or impli ed. TECHNICAL SUPPORT Phone: 613-226-5772 or 1-800-265-6681 Fax: 613-226-2802 or 1-800-561-1970 E-mail: info@avtechpulse.com World Wide Web: http://www.avtechpulse.com __________________________________________________________________ iii TABLE OF CONTENTS WARRANTY_______________________________________________________________ ____ TECHNICAL SUPPORT______________________________________________________ ___ TABLE OF CONTENTS______________________________________________________ ____ INTRODUCTION___________________________________________________________ ____ SPECIFICATIONS_________________________________________________________ _____ INSTALLATION___________________________________________________________ _____ VISUAL CHECK___________________________________________________________ _________ PLUGGING IN THE INSTRUMENT_____________________________________________ ______ OPERATIONAL CHECK______________________________________________________ _______ FRONT PANEL CONTROLS___________________________________________________ ___ GENERAL INFORMATION____________________________________________________ __ BASIC PULSE CONTROL____________________________________________________ ________ ELECTROMAGNETIC INTERFERENCE___________________________________________ ___ TOP AND BOTTOM COVER REMOVAL___________________________________________ ___ USER-ACCESSIBLE INTERNAL ADJUSTMENTS___________________________________ ___ USING THE GPIB INTERFACE_______________________________________________ ___ INTERFACE TO THE GPIB__________________________________________________ ________ AVAILABLE COMMANDS_____________________________________________________ ______ COMMAND INTERPRETATION_________________________________________________ _____ TYPICAL COMMAND SEQUENCE INTERPRETATION________________________________ _ SAMPLE PROGRAM_________________________________________________________ _______ CHANGING THE UNIT GPIB ADDRESS_________________________________________ ______ TROUBLE-SHOOTING AID___________________________________________________ _______ MAINTENANCE____________________________________________________________ ____ MECHANICAL LAYOUT______________________________________________________ ______ KEY FUNCTIONAL AREAS___________________________________________________ _______ PARTS LIST_____________________________________________________________ ___________ CIRCUIT AND WIRING DIAGRAMS____________________________________________ ______ __________________________________________________________________ __________________________________________________________________ 1 INTRODUCTION The AV-1022-C-AS4 is a general-purpose lab pulse-delay generator, which can generate waveforms of 0 to +5V in amplitude, at frequencies up to 1 MHz . Internal protection circuits limit the output duty cycle to less than 45% (±2%). The AV-1022-C- AS4 will drive 50W loads, and has a 50W output impedance. The output ri se and fall times are 10 ns or less. A monitor output is provided, which has the same pulse width, delay and frequency as the main output. The monitor amplitude is fixed at +1V (into a 50W load ). The instrument can be controlled either by the front-panel controls, or via the GPIB IEEE-488 computer interface. The control method is selected by a switch on the back panel of the AV-1022-C-AS4. SPECIFICATIONS Model: AV-1022-C-AS4 Pulse Repetition Rate: 100 Hz to 1 MHz Amplitude (to 50W): 0V (£ 20 mV) to +5V (± 0.2V) Source Impedance: 50W Delay (relative to SYNC output): 50 ns to 50 ms Pulse width (PW): 50 ns to 50 ms Rise time, fall time: 10 ns Maximum duty cycle: 45% (± 2%) Duty cycle protection: Triggering is inhibited if the settings would result in a duty cycle greater than 45% (± 2%). An overload indicator on the front panel lights when this occurs. Trigger required (Ext trig mode): +5 Volts, ³ 40 ns TTL Monitor output: +1V into 50W (+4V into 1kW) with same delay, pulse width, and frequency as the main output Period, delay and pulse width jitter: < ± 0.1% of setting ± 50ps Period, delay and pulse width long- < ± 0.5% of setting term average instability: Sync output: +2 Volts, 50 ns, will drive 50W loads Signal connectors: BNC Power requirement: 120/240 Volts (switchable), 50 - 60 Hz Dimensions (H x W x D): 100 mm x 215 mm x 315 mm 3.9” x 8.5” x 14.8” Temperature range: +10° C to +40° C __________________________________________________________________ 2 INSTALLATION VISUAL CHECK After unpacking the instrument, examine to ensure that it has not been damaged in shipment. Visually inspect all connectors, knobs and the handles. Confi rm that a power cord and instrumentation manual are with the instrument. (If the instru ment has been damaged, file a claim immediately with the company that transported the instrument). PLUGGING IN THE INSTRUMENT Examine the rear of the instrument. There will be a male power receptac le, a fuse holder and the edge of the power selector card visible. Confirm that th e power selector is in the correct orientation - it should be marked either 120 or 240, indicating whether it expects 120V AC or 240V AC. If it is not set for the proper voltage, re move the fuse and then grasp the card with a pair of pliers and remove it. Rotate horizon tally through 180 degrees. Reinstall the card and the correct fuse. In the 120V setting, a 1/2A slow blow fuse is required. In the 240V setting, a 1/4A slow blow fuse is require d. OPERATIONAL CHECK This check is to confirm that the instrument is fully operational. Set the controls to the following values: · REPETITION RATE range switch: 100 kHz position · REPETITION RATE fine control: fully counter-clockwise (minimum frequency) · PULSE DELAY range switch: 50us position · PULSE DELAY fine control: fully counter-clockwise (minimum delay) · PULSE WIDTH range switch: 5us position · PULSE WIDTH fine control: fully clockwise (maximum pulse width) · AMPLITUDE fine control: fully clockwise (maximum amplitude) · REMOTE/LOCAL switch (on the back panel): LOCAL __________________________________________________________________ 3 Connect a 50 W coaxial cable from the SYNC connector to the TRIG input of an oscilloscope. Connect 50W, 2 Watt load between the OUT connector signal line and ground. Connect an oscilloscope probe to the main output. Set the oscilloscope to trigger externally with the vertical setting at 2 Volts/div and the horizontal setting at 20 ms/div. Then follow the instructions below and compare what is seen on the oscilloscope to what is described. Only approximate values are needed to confirm operation. STEP CONTROL OPERATION RESULTS 1 POWER Push in (on) and wait +5V pulses with period for a 5 minute warm- 100ms, pulse width 5ms, and up period. rise & fall times of 10 ns. 2 PULSE DELAY Rotate fully The pulses shift to the right fine control clockwise, then fully on the oscilloscope by 50 counter-clockwise ms, then back 3 PULSE WIDTH Rotate fully counter- The pulses narrow to 0.5ms, fine control clockwise, then fully then widen back to 5 ms. clockwise 4 REPETITION Rotate fully Period falls to 11.1ms, at RATE fine control clockwise, then fully which point the duty cycle counter-clockwise exceeds 45% and the pulse triggering will stop. The overload indicator will come on. When the knob is rotated counter-clockwise, the period will increase and triggering will resume. 5 AMPLITUDE fine Rotate fully counter- The pulse amplitude falls to control clockwise, then fully 0 V, then rises back to +5 V. clockwise Steps 1 to 5 confirm that the pulse delay, pulse width, amplitude contr ols, and the duty cycle limit and internal clock circuit (controlled by the REPITITION RA TE controls) are functioning properly. Step 6 is optional, and is to confirm that the instrument can be trigge red externally. First connect a pulse generator or other signal source with a 10 kHz frequenc y, a pulse with of at least 40ns, and TTL logic levels (0 and 5V) to the EXT TRIG input connector. (The voltage applied to this input must not go below zero volts, or exceed + 5V.) Then proceed with step 6: __________________________________________________________________ 4 6 REPETITION Set at "EXT" +5V pulses with period RATE range 100ms, pulse width 5ms, and switch rise & fall times of 10 ns. Step 7 and 8 are optional, and are to confirm that the GPIB interface i s operating. 7 REMOTE/LOCAL Set at "REMOTE" No output pulses. Zero volts switch (on the out. back panel) In the absence of computer commands, the AV-1022-C-AS4 defaults to a qu iescent zero-amplitude state when in the REMOTE mode. This is demonstrated by s tep 7. To fully test the instrument's REMOTE mode, a computer with a properly- configured GPIB controller card and the appropriate software is required. Connect the controller to the AV-1022-C-AS4's rear-panel GPIB connector using the supplied GPIB c able. The AV-1022-C-AS4 is shipped with its GPIB address set at "8". Send the fol lowing sequence of four commands to the AV-1022-C-AS4 via the GPIB bus: R10000 W5 D5 V5 Then observe the output on the oscilloscope. 8 GPIB interface. Send GPIB +5V pulses with period commands. 100ms, delay 5ms, pulse width 5ms, and rise & fall times of 10 ns. This completes the operational check. __________________________________________________________________ 5 FRONT PANEL CONTROLS 2 4 6 8 13 12 10 11 1 3 5 7 9 (1) POWER switch. The POWER pushbutton switch applies AC prime power to the primaries of the transformer, turning the instrument on. (2) REPETITION RATE range switch. This selects one of the five pulse re petition rate ranges: 100 Hz - 1 kHz 1 kHz - 10 kHz 10 kHz - 100 kHz 100 kHz - 1 MHz EXT In the "EXT" position the instrument is triggered by a TTL pulse (0 to +5V) on the "EXT TRIG" connector. (3) REPETITION RATE fine control. This varies the pulse repetition rate within the selected range. (4) PULSE DELAY range switch. This controls the delay between the SYNC OUT output (see item 10) and the main OUT output (item 9). This switch sele cts one of the three delay ranges. 50 ns - 0.5 ms 0.5 ms - 5 ms 5 ms - 50 ms __________________________________________________________________ 6 (5) PULSE DELAY fine control. This varies the delay within the selected range. (6) PULSE WIDTH range switch. This selects one of three pulse width ran ges: 0.05 ms - 0.5 ms 0.5 ms - 5 ms 5 ms - 50 ms (7) PULSE WIDTH fine control. This varies the pulse width within the se lected range. (8) AMPLITUDE A fine control. This varies the output amplitude between 0 and +5 Volts. (9) OUT connector. This connector provides the main output. It will sup ply up to +5V into 50W. The output impedance is 50W. (10) SYNC OUT connector. This output supplies a TTL-level pulse (nomina lly) to trigger oscilloscopes or other measurement equipment. The output pulse width is nominally fixed at 50ns. (11) MONITOR connector. This output provides +1V into 50W (+4V into 1kW ) with same delay, pulse width, and frequency as the main output. The amplitude of this output is completely independent of the amplitude of the main output. (12) EXT TRIG connector. If the REPETITION RATE range switch (item 2) i s in the "EXT" position, the instrument will be triggered by an external TTL-lev el trigger applied to this connector. Note that this is a high-impedance input; it is not terminated in 50W. If the REPETITION RATE range switch is not in the "EXT" position, this inp ut has no effect. However, it should be left unconnected to avoid electromagnetic interference with the internal clock. (13) DUTY CYCLE OVERLOAD indicator. This LED indicator will light if th e duty cycle exceeds 45%. If this light is on, the pulse generator has stopped trigg ering and the duty cycle should be reduced. __________________________________________________________________ 7 GENERAL INFORMATION BASIC PULSE CONTROL This pulse-delay generated can be triggered by its own internal clock o r by an external TTL trigger signal. In either case, three output channels resp ond to the trigger: SYNC OUT, MONITOR, and OUT. The SYNC OUT pulse is a fixed-width pulse t hat is generated immediately after triggering. This pulse can be used to trigg er oscilloscopes or other measurement systems. The two other output channels are referen ced to the SYNC OUT pulse. This relationship is illustrated in Figure 4. 50ns B SYNC OUT 2V, FIXED DELAY PW AMPLITUDE, OUT VARIABLE MONITOR DELAY PW 1V, FIXED Figure 4 - Basic Output Pulses The delay, pulse width, and amplitude parameters indicated in Figure 4, as well as the frequency, can be varied with front panel controls or via the GPIB comp uter interface. This pulse generator incorporates a special duty cycle protection circu it, to prevent the output duty cycle (the pulse width divided by the period) from exceedin g 45%. The instrument will stop triggering if the duty cycle exceeds 45%, and will not start triggering again until the duty cycle has been reduced. (To reduce the duty cycle, either the frequency or the pulse width must be decreased.) The "DUTY CYCLE OVERLO AD" indicator on the front panel will come on if the duty cycle limit has b een exceeded. __________________________________________________________________ 8 ELECTROMAGNETIC INTERFERENCE To prevent electromagnetic interference with other equipment, all used outputs should be connected to shielded 50 Ohm loads using shielded 50 Ohm coax ial cables. Unused outputs should be terminated with shielded 50 Ohm BNC terminator s or with shielded BNC dust caps, to prevent unintentional electromagnetic radiat ion. TOP AND BOTTOM COVER REMOVAL The top cover of the instrument may be removed by removing the four Phi llips screws on the top panel. With these four screws removed, the top panel may be slid off by pulling it towards the rear. The bottom panel may be similarly remov ed. USER-ACCESSIBLE INTERNAL ADJUSTMENTS Several trimming potentiometers are accessible inside the instrument to tweak the duty cycle protection circuit, and to null any voltage offsets pres ent on the output waveform. These potentiometers are factory-set and should not normally require any adjusting. These controls can be accessed by removing the top panel, an d by locating the large, horizontal board mounted on the left-side and the front pane l of the instrument. If an amplitude-independent offset is present on the output waveform, t his can be nulled by adjusting the potentiometer labeled "OFFSET1". (The potent iometer may be obscured by a ribbon cable. Simple move the ribbon cable out of the way.) If an amplitude-dependent offset in excess of ±20mV is present on the output waveform, this can be nulled by adjusting the potentiometer labeled "OFFSET2". Three separate duty-cycle adjustment controls are present, and are labe led "DUTY1", "DUTY2", and "DUTY3". Each corresponds to a different pulse wi dth range: Adjust this control to protect this PW range DUTY1 0.05 ms - 0.5 ms DUTY2 0.5 ms - 5 ms DUTY3 5 ms - 50 ms If the protection circuit is being triggered at duty cycles outside of the 43% - 47% range for one (or more) of the PW ranges, adjust the appropriate "DUTY" poten tiometer(s). __________________________________________________________________ 9 USING THE GPIB INTERFACE The AV-1022-C-AS4 incorporates the Avtech OP1 "GPIB bus listener interf ace". This section describes how to use the IEEE 488 General Purpose Interfac e Bus (GPIB) for remote computer control of the AV-1022-C-AS4. INTERFACE TO THE GPIB The Avtech OP1 interface is a simple "listener" interface for the GPIB. It will receive simple commands from a computer over the GPIB bus, but it does not have the capability to send any data back to the computer. In more concise terms , the OP1 interface implements the following IEEE 488.1 Capabilities as defined i n the IEEE 488.1 Standard: SH0 no "Source Handshake" capability (can not send information) AH1 complete "Acceptor Handshake" capability (can receive information) T0 no "Talk" capability (can not send information) TE0 no "Talk Extended" capability (can not send information) L2 basic "Listen" capability (can receive information) LE0 no "Listen Extended" capability (because it is a basic listener only) SR0 no "Service Request" capability (because it is a basic listener only) RL0 "Remote/Local" switching controlled by a back panel switch (not computer controlled) PP0 no "Parallel Poll" capability (because it is a basic listener only) DC0 no "Device Clear" capability (can not be remotely reset) DT0 no "Device Trigger" capability (can not be triggered by the computer) C0 no "Controller" capability (because it is a basic listener only) AVAILABLE COMMANDS The OP1 GPIB user interface is designed to be used to remotely program the Avtech pulse generator to control the pulse repetition rate, delay, pul se width, and amplitude. The available commands, outputs, units and range of acceptable values f or the AV-1022-C-AS4 generator are defined in the table below: Command Acronym Function Units Range V set voltage V 0 to 5 R set repetition rate Hz 100 to 1000000 W set pulse width ms 0.05 to 50 D set delay ms 0.05 to 50 __________________________________________________________________ 10 COMMAND INTERPRETATION The command may utilize the defined single letter acronym, or may be ex panded to a longer word to make the control program easier to understand. Thi s is because letters following the defined acronym letter are ignored. For example, a command of "V2" will cause exactly the same result if the command is sent as "Volt age level of output pulse = 2". However, it is mandatory that the first letter of e ach command be one of the four defined acronyms. If desired, trailing text may be added to make the control program easi er to understand, since it will be ignored. For example, a command of "delay =0.2" will result in the same output as the command "delay = 0.2 micro-seconds". Acronyms are case insensitive, for example, "R" or "r" are the same. The number following the acronym letter may be any number in the range specified, however, the number of significant digits are limited to one part in 255 (for 8 bits of output resolution). For example, rep rate values of 128.2, 128 .3 or 128.2145 will all result in the same output. (Note that output resolution and accura cy are not necessarily the same). Numbers outside the specified ranges will be ign ored. Leading or trailing zeros in numbers will be ignored. Numbers expresse d in "exponential" format will NOT be interpreted correctly. For example, 3 e+2 will be interpreted as 3, not as 300. If an invalid command is sent, the unit will ignore the command and the previous value will remain unchanged. If an "out-of-range" value is sent, the u nit will also ignore the command. TYPICAL COMMAND SEQUENCE INTERPRETATION Assume the following commands are sent using the computer, using the appropriate command structure as specified for the user's GPIB controll er. Note that the default GPIB address is eight. R=100 V=5 D=1 W=2 __________________________________________________________________ 11 For example, for a GPIB controller from National Instruments, the follo wing set of commands would be sent: ibwrt "r=100" ibwrt "v=5" ibwrt "d=1" ibwrt "w=2" This command sequence will cause the generator to produce an output wit h a repetition rate of 100 Hz, delay of 1 ms, pulse of width 2 ms and an am plitude of 5 Volts. SAMPLE PROGRAM To illustrate the remote control process by means of the GPIB, a sample program written in BASIC is provided. While this example is prepared f or use with the B&C MicroSystems PC488 circuit card, the general principles of control apply to any IEEE 488 GPIB Controller. 'TEST of Pulser Controller OPEN "PC488" FOR OUTPUT AS #1 PRINT #1, "ABORT" PRINT #1, "CLEAR" PRINT #1, "OUTPUT 8;V", 5 PRINT #1, "OUTPUT 8;R", 100 PRINT #1, "OUTPUT 8;D",1 PRINT #1, "OUTPUT 8;W",2 END CHANGING THE UNIT GPIB ADDRESS The GPIB data bus address for the pulse generator has been preset to "8 " in the factory. However, the user may wish to change the address to any addres s in the allowed range of 0 to 30. This address may be easily changed by re-set ting the GPIB address switch on the GPIB Interface board located inside the pulse gen erator chassis. The address is set by means of a five position "Dipswitch " located on the top of a small circuit card located inside the enclosure near the top rear. Th e switch may observed to be set to the default address by noting that the Dipswitch position 4 is set in the OFF position, defining a binary address of 8. The switch setting is calculated as the sum of the switch weights in th e OFF position, calculated as follows: (a switch in the ON position it has a weight of zero): __________________________________________________________________ 12 Switch Number OFF Weight 1 1 2 2 3 4 4 8 5 16 For example, a switch with positions 1, 4 and 5 set to OFF will result in an address setting of 25 (16 plus 8 plus 1 = 25). TROUBLE-SHOOTING AID In the event that difficulties are encountered communicating via the GP IB interface, two auxiliary communications status indicators have been inc luded on the GPIB interface circuit card. These status indicators are small LED lam ps, one which flashes briefly whenever a properly addressed command is received. The second LED will light whenever an out-of-range value or invalid command is receive d, and will remain lit until a valid command with a valid in-range value is subsequ ently received. __________________________________________________________________ __________________________________________________________________