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Kentech Instruments PBG7 Manual

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Kentech Instruments Ltd.
Notes on the use of
PBG7 pulser system
Serial No. (special)
It is important to read this manual before operating the
system.
2nd April 2004

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Summary of Contents for Kentech Instruments PBG7

  • Page 1 Kentech Instruments Ltd. Notes on the use of PBG7 pulser system Serial No. (special) It is important to read this manual before operating the system. 2nd April 2004...
  • Page 2 It is the users responsibility to ensure that any apparatus connected to the output is suitably rated. Kentech Instruments Ltd accepts no responsibility for any damage or liabilities incurred in the operation of this equipment. The system contains 120W of 4kV power supplies, this can cause death or injury from burns...
  • Page 3 Check that all relevant connectors are in place on the rear panels before applying ac power. Do not disconnect the multiway connectors on the rear of the PBG7 45kV output module and PBG7 HV power supply module for 3 minutes after removing ac power.
  • Page 4 Introduction This PBG7 system is a state of the art avalanche pulser utilising a series parallel array of avalanche stacks coupled with various transformers to generate a large single output amplitude of 45kV into 50 . The instrument consists of five 19” rack mounting modules which should be mounted into a single 19”...
  • Page 5 HN pulse outputs of approx 12kV amplitude into 50 . In PBG7 configuration these outputs are used to trigger the PBG7 45kV output module using the 4 HN to HN cables provided. In PBG5 configuration the outputs can be used to drive an antenna array. The IEC power input must be connected to an outlet on the PBG7 control and trigger module.
  • Page 6 PBG7 45kV output module. The IEC power input must be connected to an outlet on the PBG7 control and trigger module. The equipment should be mounted in a suitable 19” rack. The rear panel and front panel connections should be added depending on the configuration required (PBG1, PBG5 or PBG7) as shown in the diagram below.
  • Page 7 If remote control by RS232 is employed we recommend that only screened cables should be use and that the cables should be fitted with clamp on ferrites near to the PBG7 system. The trigger signal can be generated internally or applied externally to the trigger unit. When external triggering is used, the trigger signal should be 5 volts into 50 with a fast rising edge (<5ns) to maintain the low jitter of the system.
  • Page 8 The PBG7 is controlled by the microprocessor unit with LCD display and four button keypad. On power up, the trigger input of the avalanche stack is disabled, note that it is always necessary to issue commands to the microprocessor unit via the keyboard or the RS232 interface to enable the trigger circuit and make the pulser run normally.
  • Page 9 Kentech Instruments for advice. There is a facility provided under the Stack Status menu to disable individual stacks. This may be used in certain circumstances to disable faulty stacks that are causing problems.
  • Page 10 H8 or FORTH to operate the pulser. a) Main menu On power up or on entering LOCAL mode from remote, the unit will briefly display the “Kentech Instruments” banner and then the main menu:- Run... > Test menu...
  • Page 11 PBG5 four channel trigger module (PBG5) and PBG7 HV power supply module (PBG7). If a comms fail is indicated it is necessary to investigate and rectify. Note that modules that are not powered up...
  • Page 12 PBG7Card# Run -card... > Test mode 7 is provided to help to isolate faulty stacks within the PBG7 module using a matrix method. The first and third line allow the selection of a row number and card number respectively within the PBG7 module.
  • Page 13 From this cursor postion:- Left returns to main menu Right moves cursor to under PBG7, press up/down to edit configuration then left to exit. Down moves cursor to under Test, right displays the test result summary as above. The configuration is kept in nonvolatile memory, it is stored as you exit the system status page.
  • Page 14 There is no handshake, this mode is designed to work with a simple terminal or terminal emulator. On entering REMOTE, the µP prints a “Kentech Instruments” banner, then waits for the user commands. The commands are:- RUN {cr} to enable all stacks with enable flag set and trigger, thereafter any character will...

  • Page 15: Test Results

    -ENABLE {cr} to reset low the enable flag for stack no. n LOCAL {cr} to return to local mode ok On returning to local mode, the “Kentech Instruments” banner is displayed once again on the LCD, quickly followed by the main menu.
  • Page 16 PBG7CONFIG .STATUS PBG7 configuration 86 stacks enabled ok 42 .STACKSTATUS Stack#= 42 (PBG7 stack# 20) Enable= 1 Test% = 100 100 100 ok 42 DISABLE DISABLE ? - UNDEFINED 42 +ENABLE 42 .STACKSTATUS Stack#= 42 (PBG7 stack# 20) Enable= 1 Test% = 100 100 100 ok...
  • Page 17 Stack#= 20 (PBG5 stack# 18) Enable= 1 Test% = 100 99 100 Stack#= 21 (PBG5 stack# 19) Enable= 1 Test% = 100 99 100 Stack#= 22 (PBG7 stack# 0) Enable= 1 Test% = 100 100 100 Stack#= 23 (PBG7 stack# 1) Enable= 1 Test% = 100 100 100...
  • Page 18 Stack#= 38 (PBG7 stack# 16) Enable= 1 Test% = 100 100 100 Stack#= 39 (PBG7 stack# 17) Enable= 1 Test% = 100 100 100 Stack#= 40 (PBG7 stack# 18) Enable= 1 Test% = 100 100 100 Stack#= 41 (PBG7 stack# 19) Enable= 1 Test% = 100 99 100...
  • Page 19 Stack#= 82 (PBG7 stack# 60) Enable= 1 Test% = 100 100 100 Stack#= 83 (PBG7 stack# 61) Enable= 1 Test% = 99 99 100 Stack#= 84 (PBG7 stack# 62) Enable= 1 Test% = 100 100 100 Stack#= 85 (PBG7 stack# 63) Enable= 1 Test% = 100 100 100 ok LOCAL...
  • Page 20 PBG7 control and trigger module PBG1 PBG5 four channel trigger module PBG5 PBG7 45kV output module and power supply PBG7 Note on stack numbers The parameter n here refers to the “global” stack number 0 to 85. This is a number used by the microprocessor to identify uniquely every stack.
  • Page 21 Stack faults From time to time as the PBG7 unit ages the self test routine will inevitably find faults with the system. If the measured stack voltages are low, say a readout of 80 or 90% this indicates the failure of one or more semiconductor devices. There are thousands of devices in the pulser so provided triggering is stable this will generally have an imperceptible effect on the output and is therefore not too important.
  • Page 22 1) First determine which module is causing problems. With the hardware configured for PBG7 operation you can change the software configuration to PBG5 in the system status page, then run the pulser. No power will be applied to stacks in the PBG7 module. Stable triggering now indicates the PBG7 module is at fault.
  • Page 23 2 to 5 manually in turn using the stack status pages. If the fault lies within one of these four stacks the PBG5 can still be used on 3 channels but do not operate like this in PBG7...
  • Page 24 Comms faults If a PBG5 or PBG7 comms fault is indicated check that the system control linked is correctly configured with all connectors fully engaged and retaining screws tightened and that power is applied to PBG5 and PBG7 modules. Note that if a module is connected to the system control link it must be powered up for the link to operate correctly.

  • Page 25: Specifications

    SPECIFICATIONS 1. PBG7 control and trigger module 2. Four channel delay module 3. PBG5 four channel trigger module 4. PBG7 45kV output module 5. PBG7 HV power supply module PBG7 control and trigger module Number of outputs Polarity Negative 5.8kV into 50 ohms.
  • Page 26 Splitter input N type, approx 6kV into 50 Timing: Trigger input to pulse out delay ~31ns (direct mode) ~50ns (delay mode) Trigger input to pretrig ~18ns (delay mode - delay set to minimum) Jitter <10ps RMS Controls: Mode Sets one of the following modes: Single shot (delay active) 0.05 to 0.5Hz (delay active) 0.5 to 5Hz (delay active)
  • Page 27 ~71ns (delay mode) Indicators: Power Shows that AC power is applied and the unit is switched Triggered Illuminates when the unit is triggered PBG7 output module and power supply Number of outputs Polarity negative >45kV into 50 ohms. Output amplitude <=150ps (10 to 90%)
  • Page 28 Outputs: Pulse output special Kentech Instruments connector Inputs: Trigger inputs 4 x HN approx 12kV into 50 , <100ps risetime AC power IEC, 110 to 240V ac, 50/60Hz System control 9 way D type Timing: (refered to trigger input on the trigger module)
  • Page 29 Tek S4, 7S11, 7T11 Barth 142 20dB x 2, Radial 20dB SMA x 2, suicide T x 2 or special Kentech attenuator. PBG1 output from PBG7 control and trigger module 10000x attenuation, 1kV per division, 100ps per division PBG5 channel 1 output using suicide T attenuator.
  • Page 30 PBG5 channel 2 output using suicide T attenuator. 20000x attenuation, 2kV per division, 100ps per division PBG5 channel 3 output using suicide T attenuator. 20000x attenuation, 2kV per division, 100ps per division...
  • Page 31 PBG5 channel 4 output using suicide T attenuator. 20000x attenuation, 2kV per division, 100ps per division PBG7 output using special Kentech attenuator. 100000x attenuation, 10kV per division, 1ns per division...
  • Page 32 PBG7 output using special Kentech attenuator. 100000x attenuation, 10kV per division, 200ps per division PBG7 output using special Kentech attenuator. approx. 90000x attenuation, approx. 9kV per division, 100ps per division...
  • Page 33 Prepare a taper on the dieletric of the cable Strip back the outer and slide back the braid Solder Bind with PTFE tape with silicon rubber (RTV) Slide connector forward with RTV rubber covering the PTFE. Make sure all voids are filled with RTV.
  • Page 34 Slide the braid forward and trim the length Make sure this surface is flush with the main body Bind the braid tightly with flexible copper wire Solder the braid and the wire to the brass with a large soldering iron. Do this quickly to avoid melting the dielectric.
  • Page 35 Notes on the use of DEL4 four channel delay generator Serial No. xxxxxx 11th March 2004...
  • Page 36 Specification • Number of channels • Maximum delay adjustment 20ns • Incremental delay step 25ps • Typical throughput delay at minimum setting • Interstep error <± 0.5 steps, but reproducible. • Jitter effectively zero, mechanical device. • Characteristic impedance • Voltage handling D.C.
  • Page 37 Introduction The Kentech Four Channel Delay Generator uses passive delay lines to form a compact unit designed for the critical timing adjustment of fast camera systems and other fast instrumentation. It has 4 independent channels each of which will delay an arbitrary input signal over an adjustment range of 20ns in 25ps steps.
  • Page 38 H8 or FORTH to operate the delay generator. a) Run page On power up or on entering LOCAL mode from remote, the unit will briefly display the “Kentech Instruments” banner and then the run page:- Entry# = Edit delays...
  • Page 39 The character n below denotes a number. Do not use any punctuation, eg “,” or “.” in this number, use only numbers in the ranges indicated. On entering REMOTE, the µP prints a “Kentech Instruments” banner, then waits for the user commands. The commands are:-...
  • Page 40 EEPROM (non volatile storage) LOCAL {cr} to return to local mode ok On returning to local mode, the “Kentech Instruments” banner is displayed once again on the LCD, quickly followed by the run page.