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1. RanaeUn Time Time to ranae un 87 sa 215 Range Dn Limit Timetoranaedown 88 152 216 Time Constant 89 153 217 DisolavConfa Configure Disolav 90 254 INTGRT CalHioh Part of Calibrate Number Diait o1 15 J 259 Callow Part of Calibrate Number Diait 156 220 Exponent 9 is 221 Prefix Base Prefix o4 258 gt its f BaseUnts 95 159 23 iso Toe Disolav Where D pointis 96 160 224 J Range HiLimit_ LimitforTvoeranaina un Lov 16 225 Range Lo Limit Limitforranaina down 1 98 16 226 DisolavConfa Configure the Disolav 99 163 7 NotUsed 100 228 102 166 Notused in this model 103 167 Discriminator Discriminator 104 16 22 105 169 233 Deadtime Deadime 106 170 High Voltane HiahVolaae 107 23 Saturation Saturation 1088 172 4 Notusedinths NOTES Setting for the instrument with detector Settings for Detectors not for modes MODEL 5085 MERIDIAN Health Physics Instruments 3 Descri
2. 25 Divider 14 Divider 22 Button 12 A 21 21 BUZ 13 C CAL 10 14 Calibrate 22 Cal Button 10 Factor 7 Menu 10 Mode 14 Verify CPM 7 MODEL 5085 MERIDIAN INDEX Verify Scaler 7 Calibration 7 10 Button 10 Factor 7 8 18 22 Calculating 17 Integrate Mode 8 Menu 10 15 Rate Mode 7 Check 22 Contrast 13 22 Emergency 3 CPM 13 16 CPM Timebase 11 CPS 16 Current Mode 22 Custom Settings 21 Menu 10 20 D Deadtime 5 13 16 22 23 27 Factor 7 DET 13 DET SETUP 15 Detector 13 1 2 3 13 Connection 5 23 Number 22 Sensitivity 16 Settings 18 Setup Menu 10 15 16 Variables 14 Detector Plateau 8 Discriminator 19 23 Display 12 Configuration 23 type 19 Type 23 DIV 14 DK 13 Health Physics Instruments DTM 13 E EEPROM 9 Engineering Format 23 Exponent 8 18 23 Calculating 17 EXPONENT 7 F Factory Setting 9 10 15 20 Factory Setting Menu 11 Failure 1 3 9 Reprogramming EEPROM 9 Front Panel Calibrate 22 Menu 10 11 FST 13 Function Menu 12 13 24 H 7 13 High Voltage 24 Cal 24 Calibration 9 11 Setting 18 Setting Menu 11 HLD 13 Hold 13 HOLD 13 Hours remaining 3 13 Instrument Variables 14 INT 4 13 Integrate Calibration 8 18 range 4 Range Calculation 18 Range Setup 18 Internal Timebase 12 14 16 22 Menu 11 INTG 2 Introduction 2 L Languages 27 LB
3. 25 Timebase 16 17 26 TME 4 13 U Units 16 26 Update speed 4 User Characters 26 Mode 16 Setting 24 USR 13 16 V Variables 12 14 20 Detector 14 Table 20 version number 3 W Worksheet Detector Setup 28 35
4. Contrast j bDefautis160 6 Timelt2 Time for intearate ranae 2nd Diait Setto0 O o Z 8 Timesc3 Time for scaler 3rd Digit SettoO 9 Timescl 2 Time for scaler 2nd Setto0 31 fe NotUs d J 1 User Units and Timebase 1st character User Units and Timebase 5th character Calibration number for Hiah Voltaae Presetto 94 User character at turn on displav 1st diait User character at turn on displav 2nd diait User character at turn on displav 3rd diait User character at turn on displav 4th diait Location Location Location Description Det 1 Det 2 Det 3 Mode Lockout Determines which modes in Las 112 176 X cpm CalHiah Part of Calibrate Number Diait 20 49 Caltow PartofCalibrate Number Diait 0 Exponent 51 Prefix BasePrefx 52 6 8 its j hBaseUnts 53 7 Timebase BaseTimebase 54 ue 18 iso Tvoe Disolav Tvne Where D pointis 55 uo 183 Bara Tvoe 56 120 HiLimit Limitforranginauo 57 1231 185 4 Range Lo Limit Limitforranaina down 1 58 122 186 Un Time Time to ranae un 59 123 87 Dntime_ Timetoranaedown 60 124
5. This is because these rely on the internal timebase for their calculations to make the CPM or CPS range read correctly There are several reasons to choose CPM or CPS 1 make the MOD softbutton selection of or CPS 2 To calibrate the Rate Integrate and User Ranges in units of or CPS 3 To make the or CPS range read correctly with a Calibration of 1 00 To change the internal timebase use the Setup Menu item CPM CPS SI 6 see the section on Setup Menus form more information 14 CALIBRATION MENU AND DETECTOR SETUP MENU The Calibration Menu and the Detector Menu allow interactive changes to be made to the instrument This permits changing many settings or variables while looking at an operating instrument The Calibration Menu is used in changing the Calibration of the instrument during routine calibrations The Detector Setup Menu is used for changing the settings variables and parameters when adding a new detector or changing an existing detector The two modes function exactly the same except that the Calibration Mode sets only the Calibration Factor Exponent and the Deadtime while the Detector Setup Mode sets the Calibration Factor Exponent Deadtime in out Deadtime High Voltage Saturation Window in out Window Discriminator Gain Range High Limit Range Low Limit Units Prefix and Timebase The Calibration and the Detector Setup Menus will change the parameters specific to the instrument
6. setups in the instrument It allows you to change everything changeable about the instrument Please see the section on Custom Settings for a complete description of this menu d FrontPanel 4 The Calibration and Setup Menus can be reached through the front panel or internally This menu changes the access from the front panel It also tums on and off the Adjust Menu for the Quick keys The choices are Front panel on off Adjust on off for all modes or for just the scaler See the Operational section for more information on Adjust If you want to be able to calibrate the instrument from the front panel push yes If you want to be able to access the Adjust from all modes then push yes to the next question and if you want to 10 MODEL 5085 MERIDIAN adjust only in the scaler mode push yes to the next question and no to the previous question Automatic Tum Off 5 The instrument has the capability to automatically turn itself off if itis notin use This menu turns that capability on and off If you want the instrument to automatically turn off then push yes This will automatically turn it off after the time that is programmed into the instrument The default value is 108 minutes See and power time in Custom Setting section for more information on setting the value f High Voltage Calibrate 6 The high voltage is displayed in several menus This is a measured high voltage This menu adjusts the calibration of the high voltage m
7. 188 TimeConstant Time Constant 25 189 84 DisolavConfa Configure Disolav 63 127 19 Callow Partof Calibrate Lo 28 X 192 X 65 129 Prefix Base Prefix Loc 130 its f BaseUnts 67 iu 5 Timebase BaseTimebase 68 132 196 Where D pointis 69 13 197 Bara Tvoe 70 13 4 198 Uo Limit Limitforrananauo 71 1235 199 Range HiLimit_ Limitforranaina down 72 136 200 Rance LoLimit Timetoranceun 73 123 Dn Limit Time to ranae down 74 133 20 TimeConstant Time Constant L7 139 20 DisolavConfa ConfiauretheDisolav L7 i11 205 Callow Partof Calibrate Number Diait L78 42 206 X j Etxonen Exoonent 793 m3 Base Prefix 80 124 its BaseUnts 81 25 J Timebase BaseTimebase 82 146 Disolav Tvne Where D pointis Bara Tvoe 84 212 Range HiLimit_ Limitforrananauo 85 149 Range Lo Limit Limitforranaina down 86 150
8. 255 but is linear only from 0 to 100 It is best set interactively in the Detector Setup Menu 0 Display Configuration Changes the look and feel ofthe display The Bargraph can be turned on and off as can the Numeric Display in the CPM S Rate and User modes The Display can be setto normal with the bargraph on the bottom or it can be inverted with the bargraph on the top The Bargraph scale can be setto flash DISPLAY CONFIGURATION Setting Bargraph Rate Numbers Normal Invert Flash Barg S m 1 2 3 4 5 1 136 3 39 40 Du D ff off n off ff on n on ff off n off ff on n on ff off n off ff on n on ff off n off ff on n n aed ed Need Reed e e aj Bl Wi o ed e e A wj GW w co Co uj B WI inverted Display Type There are 4 display types They change the way the data changes the prefix when it changes ranges The 4 types and their settings are 1 This is engineering format The units change every 3 decades 2 This extends the engineering format up 1 so that a prefix change will not occur when the value moves above 999 For example instead of going from 999 mR h to 1 00 R h this will go from 999 mR h to 1000 mR h with a constant zero in the right hand digit On the next higher decade change the prefix will change 3 This extends the engineering f
9. Factory Settings To program the instrument with the factory settings 1 Tum on the instrument with the MODE button pushed down If this does not result in the words Calibration 1 in the display then the Front Panel Calibration Adjust has been disabled and it is necessary to use the internal one The internal Calibration Adjust button is located through a small hole between the two battery holders in the battery compartment Push on this button while turning the instrument on The words Calibration 1 should be on the display 2 Advance the menus using the T or J softbutton until the display shows the Factory Set 9 Then push OK answer the question on CPM answer no if you want CPS or Sl units and then Yes to Are you sure It will take 30 seconds to program the entire EEPROM 3 Afteritis done programming push the Mode button to resume normal operation 4 instrument will now need to be completely recalibrated The calibration sheet that was shipped with the instrument contains the calibration factors that can be used to reprogram the instrument SETUP MENUS The Setup Menus are special menus that are different than the normal operation of the instrument These menus allow adjustment and setting of all the variables in the instrument These include for example the button definitions the calibration values the operating displays the detector settings and the defaults 1 Accessing The Setup Menus These menus are not
10. Hyperterminal program supplied with your Windows program set your com port to 9600 Baud 1 stop bit 8 data bits and no parity Set flow control to off or none Set it to the com port that you attached the cable 4 the Meridian You should see a sign on message MODEL 5085 MERIDIAN NEUTRON SURVEY METER and a prompt B TERMINAL DISPLAY Typing or will display the help menu shown below MODEL 5085 HELP MENU Q Starts Stops 1 second data transfer for rate ranges D Sets discriminator H Sets High Voltage factor CF Sets the Calibration Factor 3 digits DP auto inserted X XX CE Sets the Calibration Exponent 2 digits CD Sets the deadtime MR Changes mode to Rate MC Changes mode to CPM S MI Changes mode to Integrate MS Changes mode to Scaler V Shows all variables FOR INTEGRATE OR SCALER MODES ONLY S Starts stops resets scaler and integrator T Sets time in HH MM SS for current mode MODEL 5085 MERIDIAN Health Physics Instruments COMMANDS The settings for some commands are in hex and some are in decimal The h following a number indicates hex Q ENTER Starts and stops the data transfer in the rate range This sends outthe current level every second D ENTER Sets the discriminator The range is from 0 to FFh however the setting should be from 32h 50d and above for this version of the instrument The Calibration sheet will show the normal setting of the discriminator H ENTER
11. Panel Calibration Adjust has been disabled and it is necessary to use the internal one The internal Calibration Adjust button is located through a small hole between the two battery holders in the battery compartment Push on this button while turning the instrument on The words Calibration 1 should be on the display 2 Advance the menus using the T or J softbutton until the display shows Maintenance 8 Then push OK You are now in the Maintenance Mode a Maintenance Mode Display Description The Maintenance Mode display shows the selected item in the top left the factor in hex associated with the item in the middle and the counts from the detector for 1 second on the right Pushing the NEXT softbutton on the bottom line will change between the items The softbutton will go back to the Setup Menus The or J softbuttons change the factor HV Changes the high voltage by varying the output voltage of pin 18 of U12 HVDAC This is the reference voltage of the HV section DISCR Changes the Discriminator by varying the output of pin 5 on U12 DISCR This is the reference voltage of U15 SAT Measures the saturation voltage on the HV transformer LTE Tums the light on and off BUZ Turns the buzzer on and off Needs an external input to cause the beeper to beep DIV Changes the divider to the buzzer BAT Shows the battery voltage MONITOR Switches to the monitor program to test and examine memory Needs RS232 connection to wo
12. Sets the high voltage The range is from 0 to FFh FFh is approx 2200V CF ENTER Sets the mantissa of the calibration factor Itis a 3 digit number and is assumed to be X XX Enter it without the decimal point CE ENTER Sets the calibration factor exponent Itis a 2 digit number Type the number first then it prompts for the sign CD ENTER Sets the deadtime Itis a decimal number from 0 to 255 Always enter three digits A deadtime of 5 would be entered as 005 MR ENTER Changes to the rate range if itis enabled MC ENTER Changes to the cpm or cps if in SI units range if it is enabled MI ENTER Changes to the integrate range if itis enabled MS ENTER Changes to the scaler if itis enabled V ENTER Shows all of the variables and the factors for the current range S ENTER Starts stops and resets the integrate range and Scaler T ENTER Sets the current time in the integrate range and scaler It prompts for the hours minutes and seconds If you just push ENTER it will enter a 0 CAUTION Changing the calibration factors deadtime discriminator or high voltage will change the calibration of the instrument Vill Radiation Calibration The instrument is calibrated digitally There are no trimmers to adjust The values that adjust the calibration are stored in EEPROM memory for 40 years There are two adjustments for each detector that effect the calibration The instrument is
13. cursor over 1 place and the T softbutton will increase the value of the number positioned over cursor Using the two buttons you can change the value of either the location or the data The POWER button is a softbutton even though it is not marked Pushing it will move the cursor from the Location value to the Data value If the Data has been changed pushing the POWER button will save the data This is the only way to save the data The display will show the programming message Pushing both right hand softbuttons down simultaneously will change the softbuttons from lt and to 4 and T In this configuration softbutton will raise and lower the value of the 3 digit number that is above the cursor This makes it easier to increase or decrease values orto scroll through memory MODEL 5085 MERIDIAN Health Physics Instruments 5 When you are finished push the POWER button to save the last change then push the MODE button to to the Main Setup Menu 6 Itis a good idea to recalibrate or at least check the operation of the instrument to make sure you did not inadvertently change an important variable 2 Locations of Variables The tables below show the values in each of the locations The first table covers locations 0 to 36 The second table covers locations 25 to 27 and 48 to 255 Check Contains Adiust Power off EEPROM check value Current mode of instrument 0 CPM S 1 Rate 2 User 3 Int 4 Scaler 4
14. stops counting Check for double counting at low count rates Lower the gain or raise the discriminator to correct this problem 3 Saturation The saturation detector if installed is used to prevent a saturated detector from reading 0 on the display Setitto 0 to turn it off To adjust the setting in Detector Setup Mode 1 Reduce the Saturation to zero 2 Expose the detector to sufficient radiation so the reading is at the top of the highest scale 3 Raise the saturation until the reading shows off scale 4 Lower the saturation by 10 e Other variables and settings The bargraph type display type inverted or normal display modes for each detector and range up and down times can be reviewed under the Custom Settings section MODEL 5085 MERIDIAN Health Physics Instruments 19 CUSTOM SETTINGS MENU The Custom Settings is used to change the individual items in the instrument It can change any variable It programs by numbers and does not show the name of the variable It is necessary to refer to the tables below to determine the location of the variable and the setting for that variable A description of the variables follows the tables T Programming To program the variable first determine the variable or variables that you want to change Locate the location of that variable in the following table then determine the value or setting of the variable from the section Description of Custom Settings Finally progra
15. the Detector Max See section above on Buttons 6 Printed Bargraph scale The printed bargraph scale is between the window and the display It contains the numbers for the scale for the bargraph New scales are available from the HPI Various bargraphs are available or you can make your own with a word processor To install a scale 1 Remove the bottom case from the instrument 2 Remove the two screws that hold the front of the circuit board to the spacers The circuit board with batteries should fold away from the front panel 3 Remove the old scale itis glued in place Be careful not to scratch the display Cut out the new scale using scissors Add a small piece double stick tape to the back of the scale Replace the scale in the instrument Replace the screws and bottom case 12 FUNCTION MENUS The following is a list of all of the function menus The first three are programmed in the standard instrument Additional menus are available by programming using the Customs Setting Mode 1 LTE Backlight on the display This controls the backlight on the display The backlight is not very visible in daylight but is very visible in low light The choices are OFF The backlight is off TME The backlight is timed This turns the backlight on for 25 seconds After the 25 seconds it will automatically turn itself off The time is stopped when in the Function Menus ON This will turn on the backlight until it is turned of
16. the instrument to operate properly with the new detector This section discusses the procedures to change the current settings for the new detector 1 General The instrument is modified to accept the new detector by changing several parameters included in the list below Some of these must be changed Some may be left the default values The items marked with a are accessible from the Detector Setup Menu 1 Bargraph type 2 Calibration Factor and Exponent 3 Deadtime 4 Discriminator 5 Display Type 6 High Voltage 7 Inverted normal display 8 Modes for the detector 9 Prefix 10 Range hi low limit 11 Range Up down time 12 Saturation if installed 13 Time constant 14 Timebase for each mode 15 Units The units prefix and timebase that are selected for the display are only displayed These values do not directly change the calibration Changing the prefix from m to will not change the sensitivity of the instrument It will only change the prefix on the display The numbers on the display will remain the same To change the sensitivity of the instrument it is necessary to change the Calibration Factor and Exponent A good method of understanding the setup of a detector is to think of a traditional survey instrument with a meter The scale behind the meter the range switch and the calibration adjustment screwdriver adjust set the instrument sensitivity The scale could be removed and replac
17. the list Push the 4 softbutton to go to the pervious item on the list When you have the selection that you want push the ok softbutton The screen will then change to the new item 3 Setup Menu Selection The following is a list of menu selections in Setup Each selection has a followed by a selection number to make it easier to find If a Softbutton is labeled this means that pushing it will get back to this menu The menu selections and their definitions are listed below a Calibrate 1 This is the menu to change the calibration of the instrument Please see the Calibration and Detector Setup Menus for a full understanding of how to use this menu Also see the section on Calibration to understand the settings It is used to change the following Calibration Factor Exponent and Deadtime b Detector Setup 2 This is the menu to change both the calibration of the instrument and the setup of the detector Please see the section on Detector Setup Menu for a complete description of this menu Itis used to change the following Calibration Factor Exponent Deadtime in out Deadtime High Voltage Saturation Discriminator Range High Limit Range Low Limit Units Prefix and Timebase c Custom Settings 3 This is the menu to change individual memory locations in the EEPROM that in tum program the instrument All of the instrument variables are stored in the EEPROM This menu allows complete access to all the possible changes and
18. 5 1 271 Q 17_ 1 1 40106 9 38 HVDAG n LCD CONTRAST Lx 1 UG 3 EDATA X esx 2 285 ESA EXEC 434 DIGITAL ANALOG CONVERTER s om gi LX em vec 36 MODEL 5085 MERIDIAN Health Physics Instruments 31 21 MHV MHV 1 1 R30 10M MODEL 5085 MERIDIAN 01 0022 FR107 FR107 FR107 R31 K K A K A 81 10M DS 06 D7 Q 6007 MGR 9 Ji ans coRE 52 cz HVCURRENT 1000M R34 0022 5 ANA 2 sl R35 n 8 4 100K 25 255 TO 5 vec Health Physics Instruments vec R36 100K ay D Q2 e 833 F N7 s VN10Km vec 470K R28 z 8 C17 vcc TP13 COUNTS LM393JA HVREAD 5 TLC272 AAA HVDAC R59 se 2 4 5 74HC14 Ute LP339NA U21 B XX1 PXX1 5 1 1 CS BUZZER BEEPER Bu U2 C U15 B 4001 LM393JA 9e U21 C 1 U21 D 4 LP339NA LP339NA ct MPs6534 2 4124 2951 1 2951 022 44 2 PX2 2 Er LOW VOLTACE POWER SUPPLY NEGATIVE VOLTAGE GENERATOR MODEL 5085 MERIDIAN Health Physics Instruments 33 Adjust 10 11 21 22 11 On Off 11 Using 11 Appendix A Worksheet 28 Automatic Turn Off Menu 11 B Backlight 13 Bargraph 4 Log 19 22 Printed Scale 12 type 19 Type 21 Battery 3 Change 5 Low 4 5 Beeper 13
19. AT 4 LCD 13 LT 13 Maintenance 9 Menu 11 Mode 9 MED 13 Memory Locations 20 Menu Adjust 11 Calibration 15 Custom Settings 20 Function 13 Selecting 10 Setup 10 Viewing 10 MHV 5 34 MOD 13 Mode 12 13 Calibrate 14 Description 4 Lockout 24 Rate 4 User 16 MODE 2 4 N NEXT 2 Numeric display 4 NXT 13 13 14 13 14 Operational 5 13 Overrange 4 Plateau 8 18 Power Off 22 Time 24 User 24 POWER 2 3 Prefix 16 17 25 MODEL 5085 MERIDIAN Table 18 28 Problems 27 Programming 14 Custom Settings 20 Setup Values 19 Q Questions 27 Quick Start 2 Quick key 3 10 12 Programming 21 Table 21 R Range Calculating Maximum 17 Calculating Minimum 17 Down Time 25 High Limit 17 25 Integrate 4 Low Limit 17 25 Up Time 25 Range High Limit Calculating 17 Integrate Range 18 Range Hold 13 Range Low Limit 18 Integrate Range 18 Rate Ranges 16 Reset Emergency 3 RH 13 Health Physics Instruments RS232 6 RST 4 RTE 13 5 Saturation 19 25 27 sav 11 Scientific notation 7 SCL 13 serial 6 SET 13 Set Time Mode 4 SETTIME 4 Settings 16 Setup Menu 10 Menus Accessing 10 Programming 19 Setup Menus 10 SFT 13 SLO 13 Softbutton 24 Specifications 1 Stats 25 STP 4 TC 13 Terminal 6 Time Integrate Range 25 Scaler 25 Setting 4 TIME 2 Time Constant 13
20. Crystal Display Contrast Setting The LCD controls the contrast of the display There is only one choice and it is SET Pushing it will change to a new display The best setting is as dark as possible before the squares show The choices of this menu MODEL 5085 MERIDIAN Health Physics Instruments LT To lighten push and hold down DK To darken push and hold down NXT When the contrast is correct push this button 6 BUZ Beeper Control This controls the beeper The beeper has 2 functions In the CPM Mode or Rate Mode the beeper will if turned on beep on every input pulse In the Integrate Mode or Scaler Mode the beeper will if turned on beep when the timer counts down to zero to signal that the counting is finished The choices are OFF The beeper is off SFT The beeper is turned on and the loudness is soft ON The beeper is turned on and the loudness is set to the highest level If the beeper is set to SFT then that is the loudness for the beeper The front panel Softkey used for beeper on off will only turn the beeper on to the loudness set in the Function Menu T DTM Deadtime Deadtime correction is used to compensate for the loss of counts at high count rates The actual deadtime calibration and constant is set in the instrument at the time of calibration The choices are IN This mode has deadtime correction OUT This mode has no deadtime correction The deadtime correction is turned on and off independently f
21. Fill out this table like the Example to determine the min and max range Min Range Range Lo Limit Remember the Maximum range is the range above the highest displayed DETECTO DISPLAY DISPLAY RANGE WITH EXAMPLE GM 3a Prefix Setting Units Setting Same as Rate YES NO If no use step 3b directly 2 Ie If yes Cal Factor x 60 CPM or 3600 CPS put value below 3b Calibration Factor Exponent OVERALL DETECTOR SETTINGS Either Calculate or use Detector Setup 6 Menu interactively Either way record 7 1 3b Discriminator Season eat Program the above values using the Detector Setup Menu MODEL 5085 MERIDIAN Health Physics Instruments MODEL 5085 MERIDIAN Health Physics Instruments 29 APPENDIX SCHEMATICS Health Physics Instruments 5085 002 REV C C32 L 1 IPB yo R53 Rus Oui S 0 R59 MODEL 5085 MERIDIAN Health Physics Instruments ON BUTTON RESET 27C256 27C510 EPROM sg 92 LCD ALPHANUMERIC DISPLAY B b A15 MPS6534 SPKR 2 LIGHT MODE ER LCD BACKLIGI ON amp 91 56534 ov o5 20K d RA sie 8 EARPHONE LCD READ DATA ix LCD WRITE DATA 22uF C5 LCD READ STATUS A000H Y LCD WRITE STATUS 8000H m E m OUT PORT WRITE 7000H 16 U10F RESET M gt
22. MODEL 5085 MERIDIAN NEUTRON SURVEY METER November 2000 Health Physics Instruments 330 D South Kellogg Ave Goleta CA 93117 OPERATIONS AND PROGRAMMING MANUAL C ADDING AND USING UST SIMPLE WAY TO CHANGE Table of SOME SETTINGS 11 CUSTOMIZING THE MERIDIAN 12 Contents SPECIFICATIONS MECHANICAL ELECTRICAL OPERATIONAL RESPONSE ENVIRONMENTAL INTRODUCTION D E FUNCTION MENUS 13 F PROGRAMMING 14 G CALIBRATION MENU AND DETECTOR SETUP MENU 15 H SETTING UP A DIFFERENT DETECTOR 16 CUSTOM SETTINGS MENU 20 QUESTIONS amp PROBLEMS 27 APPENDIX WORKSHEET 28 2 IL APPENDIX B SCHEMATICS 30 INDEX 34 QUICK START OPERATION TURN ON AND OFF EMERGENCY RESET AND CONTRAST MODES RATE INTEGRATE SETTING THE TIME OPERATIONAL DETECTOR CONNECTION LOW BATTERY BATTERY CHANGE DEADTIME CORRECTION OPERATION OF THE RS232 OPTION OPERATION TERMINAL DISPLAY COMMANDS RADIATION CALIBRATION CHANGING THE DISPLAY TO THE CALIBRATE MODE CALIBRATION EXPONENT AND DEADTIME FACTORS RATE MODE CALIBRATION INTEGRATE MODE CALIBRATION CAL FACTOR FOR INTEGRATE RANGE AND RATE RANGE DETECTOR PLATEAU IX PROGRAMMING AND 9 MAINTENANCE 9 SETUP MENUS 10 acl I lt lt sera o N AAO O A Ww IQ gt MODEL 5085 MERIDIAN Health Physics Instrume
23. Settings These are settings that effect the operation of the instrument This includes the display and the buttons The other type of setting is the Detector Setting These effect the operation of the detector and include the calibration data high voltage setting and discriminator 2 Programming the Meridian The Meridian is highly programmable There are many different items about its operation that can be changed There are 4 basic ways to program the instrument 1 Use the factory settings This is the simplest way The instrument is setup with all the important operating parameters and settings It takes no time 2 Use the Custom Settings menu and configure the instrument to your exact liking This is the hardest way of programming and takes some understanding of the instrument as well as some time It will result in an instrument tailored to your application or to your specifications 3 Instrument and Detector Variables The Setup Menus will change the variables inside the instrument These variables control the function of the instrument There are several types 1 Variables that change the instrument rather than the detector and are considered part of the instrument For example the beeper on off the full scale bargraph and the button definitions 2 Variables that change with Detector 1 2 or 3 These fall into two groups 1 Those that change with the Mode such as the Calibration the Units the Timebase and the Bargraph t
24. TS TABLE Setting Beeper Volume Beeper Beeper volume Beeper all rate Int Scaler int scaler all rate ranges ranges Fo sot sof sof sof sof MODEL 5085 MERIDIAN Health Physics Instruments ff Time Constant This sets the speed of the bargraph and the rate of change of the display It is also set by the TC softbutton TIME CONSTANT Time Constant Time Constant fea Stow 1 l gg Time Int This is the setting of the time for the time in the integrate range It is set by the integrate range Time Intl is the MSB ofa 3 byte HEX number Each portion of the number is presented in decimal The 3 byte number is the number of seconds that are in the display It is preset to 60 which makes the display turn on with 60 seconds or 1 minute There would normally be no reason to change this setting hh Time Scl This is the setting of the time for the scaler It is set by the time in the scaler Time Scl1 is the MSB of a 3 byte HEX number Each portion of the number is presented in decimal The 3 byte number is the number of seconds that are in the display Itis preset to 60 which makes the display turn on with 60 seconds or 1 minute There would normally be no reason to change this setting ii Timebase This has 4 possible settings and sets the characters in the display Changing this does not change the calibration TIMEBASE TABLE 25 Units The units sel
25. ach of the 4 Plotthe High voltage vs counts on a graph above items 5 Adjust the high voltage in the instrument to the value that corresponds to midway on The other way is to use the Custom Settings Menu which allows programming the plateau If there is no upswing then adjust it above the knee into the locations in EEPROM This is more complicated and involves looking up the locations of each item in the list We recommend using the Detector Setup Menu Remember that the Detector that is selected using the Function Menu will be the detector whose parameters you are saving or changing See the individual SET HIGH sections on how to use these Menus 1000 KNEE VOLTAGE TO MIDPOINT If you have problems with the programming and the instrument is functioning in an unpredictable manor you can revert back to the factory settings under the COUNTS Setup Menu however the values for the previous calibration will be lost g Log Bargraph If you have a Log Bargraph the Range Low Limit sets the low end of the bargraph Set the Range High Limit as you would if using a normal bargraph The with the UPSWING log bargraph the digital display will change ranges at each decade 4 PLATEAU 0 0 1050 HIGH VOLTAGE GRAPH OF HIGH VOLTAGE VS COUNTS 2 Discriminator The Discriminator is set by lowering the value to the point where the instrument will count from noise then raising it past the point where it
26. adjusted by changing the calibration factor with exponent and the B deadtime The Rate Mode and the Integrate Mode need to be calibrated Changing The Display To Calibrate Mode A CHANGING THE DISPLAY TO THE CALIBRATE MODE 1 Tum on the instrument with the MODE button pushed down If this does not result in the words Calibration 1 in the display then the Front Panel Calibration Adjust has been disabled and it is necessary to use the internal one The internal Calibration Adjust button is located through a small hole between the two battery holders Push it while turning the instrument on The words Calibration 1 should be on the display 2 Push the OK softbutton and the Meridian will resume normal operation with the radiation value on the top line and the calibration factor on the bottom line 3 The softbuttons change the numeric value in the bottom line of the display The lt Softbutton will move the cursor over 1 place and the T softbutton will increase the value of the number positioned over the cursor Using the two buttons you can change the value of the displayed item in the bottom line The radiation level in the top line will change along with the changes in the bottom line 4 In the Rate mode the item on the bottom line can be changed by pushing MODE then the 4 or T softbuttons until the item description is what you C wantto change or do Then push the MODE button to return to the calibration If you do not push the J o
27. and to the detector Some of the variables are specific to the instrument and detector and some are specific to only the detector Changing the Range High Limit will change the values for the selected Mode for that detector If the current mode is the Rate Mode and detector 1 is the current detector then only the Rate mode for detector 1 will be changed Likewise changing the high voltage while detector 1 is selected will change the high voltage only on detector 1 The Calibration Factor Exponent Range Hi and Low Limit Units Prefix and Timebase are all Mode and Detector specific The High Voltage Deadtime Saturation Window Discriminator and Gain are only detector specific and will not change with mode The following describes how to enter into the Calibration Mode or the Detector Setup Mode using the Calibration and Detector Setup Menus 1 on the instrument with the MODE button pushed down If this does not result in the words Calibration 1 in the display then the Front Panel Calibration Adjust has been disabled and it is necessary to use the internal one The internal Calibration Adjust button is located through a small hole between the two battery holders in the battery compartment Push on this button while turning the instrument on The words Calibration 1 should be on the display 2 want the Calibration Mode Push the OK softbutton If you want the Detector Setup Mode then push the T softbutton until DET SETUP 2 i
28. are the same as the Standard Instrument Preset combined with the Bf3 detector In addition it sets up and programs all the other parameters such as contrast user characters and current mode to start the instrument operation off properly See the section on Factory Settings in Maintenance This is also the menu to change the internal timebase from CPM to CPS Internally the instrument calculates the basic rates from counts per minute or counts per second This control changes that setting If this setting is in CPS then any presets for Preset Instrument or Preset Detector will be in SI units If you want CPM answer yes to the question CPM Timebase For more information see the section on Programming Internal Timebase Health Physics Instruments ADDING AND USING ADJUST Simple way to change some settings Adjustis a method of changing the settings for the detector without using the Setup Menus Itis designed to allow quick field adjustments without cumbersome button pushing The Adjust Menu is accessed by pushing the and A buttons atthe same time If adjustis enabled the Adjust Menu will be displayed If itis disabled it can be turned on by Adjust can be set to operate in either all modes or justthe scaler mode Adjust allows simple adjustment of the High Voltage Discriminator Window Window in out and Gain This is an interactive adjustment that is made while looking at the count rate a Tuming Adjust On And Off Adjust is
29. ason for using CPM or CPS One of the choices with the MOD softbutton in the Function Menu during normal operation is CPM If you wantthis to be CPS then you must choose the CPS internal timebase If you want itto be CPM then you must choose the CPM internal timebase If you change this setting then you must recalibrate the instrument For more information see the section on Programming Internal Timebase p Current Mode This is the current mode Set it to a mode that is currently in use Also see Mode Lockout CURRENT MODE TABLE MODE CPM S RATE USER INTEGRATE SCALER v cn Tq 3 k deadtime This should be the Deadtime for the detector and if the Deadtime is turned on will correct for dead time losses at high count rates Set itin microseconds from 0 to 255 1 Detector This is the current detector that is in use It determines which detector is in use nothow many detectors Setto 0 if you have only 1 detector Setitto 0 if you have several detectors and use the DET softbutton in normal operation to change the value Its value is changed every time the detector number is changed m Detector Max 22 This limits the number of detectors that can be selected by the DET softbutton in a Function Menu Set itto 1 for 1 detector 2 for 2 detectors and for 3 detectors n Discriminator This setting may also be though of as a threshold Itshould be set high enough that there are no counts from noise It may be set from 0 to
30. available in any of the normal operating modes There are 2 ways to enter into the Setup Menus The first method which is always available is to push a switch on the inside of the case The second method is through the front panel but it may be user disabled The two methods are a METHOD 1 INTERNAL BUTTON 1 If the instrument is on tum it off 2 Remove the battery cover on the back of the display box 3 Between the two battery holders is a small hole Push the pushbutton behind this hole while you are turning on the instrument Use a paperclip or any other small item that will fit through the hole The display should show the first Setup Menu MODEL 5085 MERIDIAN Health Physics Instruments b METHOD 2 EXTERNAL BUTTON 1 Ifthe instrumentis on turn it off 2 Push the MODE button and hold it down then push the POWER button Continue to hold down the MODE button until the Setup Menu appears If the regular turn on menu appears instead then the front panel has been disabled and itis necessary to use the internal button in Method 1 2 Scrolling Through The Setup Menus The Setup Menu is the main menu that directs you to several other menus or operations The top line of the display shows the selection that is offered followed by a number Each item is numbered and has a before the number to identify it The bottom line contains the T softbutton and 4 softbutton and the ok Softbutton Push the Tsoftoutton to go to the next item on
31. cale that may not be usable because of saturation or excessive deadtime losses RANGE HI LO TABLE Center is the point of calculation for the calibration Higher means the ranges with more counts Lower means the ranges with fewer counts Range decade Range decade 128 XXX Center 127 X 45 129 XXX 106 XX 10 105 XX 131 24 KT 12 XX O 133 KT Bi XX i4 XX XXX a XXX o Higher 19 xxx Range Up Dn Time This is the number of seconds that it takes the rate ranges to change ranges The value set is the number of seconds Itis normally set to 0 Setting the Up Time to 3 for example will delay moving up a range for 3 seconds dd Saturation This is useful to check if the detector is in saturation or drawing too much current It should be set interactively with the detector under the Setup Menu Its range is from 0 to 255 If itis settoo high it could cause the instrument to read off scale on all ranges with no detector ee Stats This controls the beeper status It is normally set and adjusted by the BUZ softbutton depending on the Mode The loud soft adjustment also effects the Quick key when it is set to beeper on off Set the loud soft correctly if you want the Quick key to be soft or loud and you have no BUZ softbutton Set this if you have no BUZ softbutton STA
32. e has less than 8 hours it will beep three times to indicate that the batteries should be changed Bargraph Scale 150 mRem h Bargraph B EMERGENCY RESET AND SPEAKER CONTRAST POWER LIGHT If the batteries are good and the instrument will not turn on it is possible that the ON OFF MODE instrument is actually turning on but the contrast is set too light or dark To do an emergency contrast setting turn the instrument on while holding down the speaker button Wait 2 seconds then release the button Then hold down the speaker button if the display is too light If the display is too dark then hold down the light button Continue to hold the button down until the display shows a normal contrast and the contrast menu Then push the NEXT softbutton to resume normal operation The instrument can be reset by holding down the POWER button for 10 seconds or until the display blanks then releasing it This is a cold start for the microprocessor It will reset the instrument which should then show the tum on display This can be done at any time to reset the instrument and is the same as turning it off then back on MODEL 5085 MERIDIAN Health Physics Instruments 3 MODEL 5085 MERIDIAN V Modes Below is a description of the different modes Change between the modes by using the MODE softbutton the button below the speaker symbol in the Function Menu Press MODE to view the Function Menu RATE The rate display can be identif
33. e Integrate range Calibration Factor 3 Expose the detector to a known dose in a radiation field that is at the lower end of the sensitivity of the detector 4 Change the Calibration Factor and Exponent Repeat step 3 until the reading is correct 5 Expose two lower ranges at 8096 of full scale Note the readings on the calibration report The deadtime correction is already set in the Rate Mode 6 Tum the instrument off by pushing the POWER button when finished CAL FACTOR FOR INTEGRATE RANGE AND RATE RANGE The rate range calibration factor can be used to setthe integrate range If you are satisfied with the rate range calibration you may be able to use the rate range calibration factor as the basis for calculating the integrate range calibration factor You may also choose to calibrate them independently If the integrate range is in the same prefix units as the rate range then the rate range Calibration Factor can be used in calculating the integrate range Calibration Factor If the rate range is in mR h and the integrate range mR then they are considered to have the same units Divide the rate range Calibration Factor with Exponent by 60 if the internal timebase is in CPM Conventional Units and by 3600 if the internal timebase is in CPS 51 units Use this new calibration Factor and Exponent for the integrate range If you use this Calibration Factor then the rate range and integrate range will have the same calibratio
34. e also available Units Conventional and SI units Rate mode Shows numeric value of rate Updated every second Limited to 3 significant digits Autoranging Integrate mode Shows Integrated dose Also shows integration time Count down and count up for time Bargraph Moving digital pointer on background of scale markings Updated 10 times every second Bargraph width is 3 in 7 6 cm Full scale markings are actively shown on the display RESPONSE Range 0 01 to 10 000 mrem h Accuracy Within 196 or 2 digits for count rates independent of detector Timebase is crystal controlled Health Physics Instruments Time constant Dynamically set depending on count rate but has settings of short medium and long Dead time correction Corrects up to 4 times actual rate ENVIRONMENTAL Temperature range 20 C to 50 C Humidity range 0 to 9596 non condensing Instrument may be in taken through the condensing phase with the addition of a desiccant pack Introduction The model 5085 Meridian is a highly functional Neutron instrument It may of course be used in general surveying but it will also find use in counting labs medical applications and non technical radiation monitoring The Meridian handles all of these tasks simply The standard instrument with factory settings has one menu and 4 front panel keys Some of the features are e Deadtime correction e Autorange with minimum and maximum scales e Rate
35. e on the worksheet 17 The GM example is shown in the Example column It has the units prefix timebase of mR h which was the chosen basic units and prefix in the three locations marked 0 under Range With Prefix Units With the GM detector example the maximum range as calculated above is 971 mR h 971 would be displayed on as XXX as shown in row 10 Since itis almost at the end of the range it is best to leave that range whole The Range Hi Limit would be set to 3 for this example The lower range is best to calculate and would correspond to about 600 CPM or 10 CPS Full Scale If the range goes lower than this then it may not be usable The calculation is Lowest Count Rate x Calibration Factor Where the Lowest Count Rate is 600 CPM if the internal timebase is CPM or 10 CPS if the internal timebase is in CPS For the example this would be 600 x 4 76 x 1 0 286 mR h This would be on range 1 on Detector Setup The Range Low Limit would be set to 1 in the Detector Setup Menu DETECTO DISPLAY DISPLAY RANGE WITH EXAMPLE R SETUP PREFIX GM Detector The Row is used for identification purposes only This column represents the prefix The three places marked 0 would have the basic prefix units timebase The three marked 1 would have the next lower prefix units timebase The three marked 1 would have the next higher prefix units timebase See the example column The above table shows the range of the instrument The 2nd colum
36. eading zero raise the high voltage until it reads a low value 6 Raise the high voltage in uniform steps of 50 volts At each step note the radiation level Do not go above the maximum voltage for the detector Plot the High voltage vs reading on a graph Adjust the high voltage in the instrument to the value that corresponds to midway on the plateau If there is no upswing then adjust it above the knee SET HIGH 1000 KNEE VOLTAGE TO MIDPOINT COUNTS UPSWING 4 k PLATEAU 0 0 1050 HIGH VOLTAGE GRAPH OF HIGH VOLTAGE VS COUNTS IX PROGRAMMING AND MAINTENANCE The Programming and Maintenance section of the manual contains items that are outside the scope of normal operation and calibration You will be interested in this section if you want to customize the Meridian use a different detector or troubleshoot the electronics MAINTENANCE 1 Maintenance Mode This mode is useful for checking the operation of the instrument when it is needed for repair Each menu item is used for checking or changing some electrical part of the instrument If you do decide to change the settings with this menu remember to disconnect the detector in case the high voltage changes This mode does not change any stored value The maintenance mode is reached through the following 1 on the instrument with the MODE button pushed down If this does not result in the words Calibration 1 in the display then the Front
37. easurement so the value will be displayed correctly It does not change the actual voltage of the high voltage See the section on Maintenance for more information g High Voltage Setting 7 This menu will adjust the setting of the high voltage It allows you to preset the value of the high voltage for a particular detector without having to go into any other Menu The top line of the display shows after the HV the actual measured value of the high voltage The number after the Fac is the high voltage factor which is a number that the instrument uses to set the high voltage It is also the number thatis put into the memory to represent that high voltage Select which detector you want to change using the det softbutton The choices are detector 1 2 or 3 Use the or T softbuttons to change the value of the factor which in turn raises and lowers the actual high voltage Save the data by pushing the sav softbutton after which the menu will change back to the or Setup Menu To change another detector just push the ok softbutton h Maintenance 8 This menu will allow adjustment of several parameters without changing their permanent values The adjustments include high voltage discriminator saturation light beeper divisor and battery In addition it will allow the use of a monitor program See the section on Maintenance for more information i Factory Setting 9 This setting is used atthe factory to presetthe instrument The settings
38. ect which units are used in all modes except the Scaler kk User 1 Thru 5 This allows any characters to be used for the units and timebase If user is chosen under Units then these 5 characters will occupy the space for units and timebase They are normal ASCII characters Each one needs to be programmed with its own character User 1 is the left hand character ASCII CHARACTER TABLE 32 space 48 a p e i 6 fa o 3 s 2 6 ppt pu den s s a s s t as v pe 8e 1 Setting 2 Character There are settings from 0 to 255 however they are not normal ASCII characters If you need a strange character please contactthe factory MODEL 5085 MERIDIAN Health Physics Instruments 26 QUESTIONS amp PROBLEMS There are many questions and problems that can occur with the Meridian We recommend reading the pertaining sections to try to understand the instrument Most problems will occur because of incorrect programming Q I programmed the instrument using the custom settings and now get gibberish on the display when cycle through the second screen of the Function Menu A The gibberish is a result of an improper programming choice in the Custom Settings If the choice is not among those that are in the tables then the instrument will choose a non existing choice and print gibberish on t
39. ed The new scale could have very different units That in itself would not calibrate the instrument you would still have to change the calibration adjustment with a screwdriver to obtain a correct reading The Meridian is very similar The Units Prefix and Timebase are just like the printed scale Changing them will not change the reading It still will have to be adjusted with the Calibration Factor and Exponent which can be thought of as the screwdriver adjust The big difference between the Meridian and a traditional instrument is that the Meridian will automatically select the next higher or lower prefix when it needs to change ranges rather than relying on the range switch MODEL 5085 MERIDIAN Health Physics Instruments 2 User Mode The User Mode is programmed just like the Rate Mode except itis called USR in the MOD function menu To tum it on use the Mode Lockout location in the Custom Settings Menu 3 Determining The Different Settings The Calibration Factor Exponent Prefix Units Timebase and Range limits all need to be calculated for each detector The high voltage discriminator gain and saturation also need to determined Use the Detector Worksheet in the Appendix as a guide to this operation It is a good idea to determine the settings that you want to use for the detector before programming the Meridian We recommend changing the Calibration Factor and Exponent of only the rate and integrate ranges The Calibration
40. ed to fit your needs Particularly important is the full scale range of the bargraph We have it set at 10 for the factory settings however many survey meters have 50 500 and 5085 CPM full scale primarily to put background counts from pancake GM detectors farther up the scale If you wanted to emulate one of these meters change the Bargraph Type to 2 in Custom Setup There also is a 2 5 25 250 and 2500 full scale available If you are using the instrument in areas where the bargraph may confuse some people you can turn it off by setting the bargraph to off in Display Configuration in the Custom Setup Menu J ust read the current value look at the table and find out the current settings Then look for the same settings but with the bargraph off and change the data to the new value We also offer the choice of normal or inverted display with the bargraph on top This may be useful for some applications where you need 2 different bargraph scales perhaps one a log scale for mR h and one a linear scale for CPM The Range Up and Down Time allow the instrument to dwell on a range without going up or down a range quickly The Range Up Time would be useful for MODEL 5085 MERIDIAN Health Physics Instruments contamination surveying near background where there are hot spots It would keep the range from going to the next higher range quickly It may be set to 2 or 3 seconds Likewise you may be using the detector in high radiation levels and not wa
41. ent are in reality a number in scientific notation A Calibration Factor of 6 35 and an exponent of 2 is in scientific notation 6 35 x 102 The Calibration Factor should be set in the range of 1 00 to 9 99 Raise and lower the exponent to compensate if it is necessary to go beyond these limits For example if the Calibration Factor is 9 5 and the Exponent is 3 then an increase of 10 would be 9 5 x 1 1 10 45 This is notin the range of 1 00 to 9 99 so decrease the Calibration Factor by 10 and add one to the exponent which would be 1 04 with an exponent of 4 The same is true of the other direction If the Calibration Factor is 1 24 and the Exponent is 3 and it is necessary to decrease it by 3096 then 1 24 would be reduced to 868 This is below 1 00 so decrease the exponent by 1 to 2 and increase the Calibration Factor by 10 to 8 68 The range of the Exponent is from 40 to 40 In reality it should never be necessary to Set it over the range of 8 to 8 The deadtime is in units of microseconds It should be close to the value specified by the manufacturer of the detector Its value is from 0 to 999 It will be adjusted during the calibration RATE MODE CALIBRATION 1 Tum on the instrument by pushing the POWER button If the units of mRem h are not displayed in the display then push MODE Push the MOD softbutton until RATE is displayed above MOD Then push the NEXT Softbutton MRem h should now be the units in the display Enter into t
42. f 2 MOD Mode The mode controls which mode the instrument is operating in The previous section describes each mode in detail The choices are CPM This is the CPM Mode RTE This is the Rate Mode INT This is the Integrate Mode SCL This is the Scaler Mode USR User Mode not factory installed 3 TC Time Constant The Time constant controls how fast the bargraph will move to a new value and how fast the digital display will home in on a new value It does not work in the Integrate or Scaler Modes The instrument automatically adjusts the time constant depending on the level of the radiation It is slow on low rates and fast on high rates The Time Constant setting modifies these automatic setting to be slower or faster The choices for the Time Constant are SLO The Time Constant is slow MED The Time Constant is medium FST The Time Constant is fast 4 RH Range Hold Range hold will keep the CPM Mode and the Rate Mode range in the same range thus keeping it from going up or down a range It is useful when surveying for low count rates when you do not want to wait for the instrument to range up to higher range for a hot spot A small will appear on the top right hand side of the display indicating the Range Hold is in effect The choices for the Range Hold are OFF Range Hold is turned off HLD Range Hold is turned on and the instrument will not range up or down a range The in the display tums on 5 LCD Liquid
43. fix units timebase then think about changing the prefix up or down to compensate A detector with 50 000 CPM mR h has the prefix set too high It should be reduced to 50 CPM uR h in which case the prefix would be If the internal time base is set to CPS then determine the CPS prefix base timebase units For example for a pancake detector that should read in uGy h determine the CPS uGy h which is 3 5 CPS uGy h If this number is below 0 01 CPS prefix units timebase or above 1000 CPM prefix units timebase then think about changing the prefix up or down to compensate Take the reciprocal of the number and convert to scientific notation For example 1 2100 0 000476 4 76 x 10 The formula is l sensitivity in prefix units timebase This is the calibration number In the example 4 76 is the Calibration Factor and 4 is the Exponent The range of the Exponent is from 10 to 10 If itis beyond this range change the prefix and recalculate the Calibration Factor and Exponent Note these values in the worksheet 5 Calculating the Maximum Level The Maximum Range is calculated from the maximum level that can be displayed with the detector which is determined by its deadtime 1 Calculate the maximum level CPM or CPS that can be used for the detector If the deadtime correction is turned on the instrument can be operated at a higher rate than if it is turned off The instrument will count up to 1 million CPM or 16 666 CPS with dead
44. hange the batteries remove the bottom ofthe enclosure by twisting the twist lock connectors on each end ofthe instrument counter clockwise This should release the bottom of the instrument Remove it and turn the instrument over There are the 6 AA cells Remove the existing batteries and replace them with new ones Replace the bottom of the enclosure If the batteries have leaked into the bottom of the instrument wash the case bottom thoroughly with soapy water then with clear water Dry it and replace it on the instrument Do not wash the circuit board The battery holders may need to be cleaned with a dampened cloth or sponge D DEADTIME CORRECTION The Factory settings turn on the deadtime correction in the Rate Mode and the Integrate Mode MODEL 5085 MERIDIAN Health Physics Instruments OPERATION OF THE RS232 OPTION The RS232 Option sends the current display data out the serial connector for viewing terminal or computer running a terminal program A OPERATION The Meridian with RS232 Option is supplied with a cable with a small round connector on one end and a rectangular 9 connector on the other end To hook up the cable 1 Connect the small round connector into the jack on the right of the front panel of the Meridian It pushes in place To remove it push on the black bump on the connector 2 Connect the other end to com port in your computer This is usually com 1 or 2 3 Using the Terminal or
45. he Calibrate mode as discussed above in Changing The Display To The Calibrate Mode 2 Change to the Rate Mode If the Rate Mode is not displayed then push MODE Repeatedly push the MOD softbutton until RTE is displayed above MOD Then push the NXT softbutton twice The Rate Units should now be in the display 3 Expose the detector to a radiation field that is at the lower end of the sensitivity of the detector With a Bf3 Detector Normal 5085 this is 10 to 50 mRem h Change the Calibration Factor and Exponent until the reading is correct 4 Expose the detector to field that is at the upper end of the sensitivity of the detector With a Bf3 Detector Normal 5085 this is 5085 to 10 000 mRem h Adjust the Deadtime until the reading is correct 5 Repeat steps 3 and 4 until both settings are correct 6 Expose each range decade at 20 and 80 of full scale Note the readings on the calibration report 7 the instrument off by pushing the POWER button when finished INTEGRATE MODE CALIBRATION 1 Enter into the Calibrate mode as discussed above in Changing The Display To Calibrate Mode 2 Change to the Integrate Mode If the integrate Mode is not displayed then push MODE Repeatedly push the MODE softbutton until INT is displayed above MODE Then push the NEXT softbutton twice The Integrate range should now be in the display Read section E below to determine if you wantto use the Rate Range Calibration Factor to setth
46. he display Look atthe numbers in locations 18 through 26 using the Custom Settings Menu The selections should be in the range from 0 to 12 Q I want to use 2 detectors but I can t figure out how to change to the second detector A If you can t change the detectors this means that you don t have the DET function in the Function Menu You will need to add it by changing one ofthe selections in location 18 through 26 in the Custom Settings Menu These locations correspond to the left center and right buttons of the first second and third Function Menus To see what the current choices are look them up in the chart of Function Menu Definitions chart and then change one ofthe locations You will change itto an 8 which is the detector selector Incidentally you probably are not using all three Function Menus and your choice will be either to change one of the existing softbuttons to this function orto add itto a new Function Menu by adding a Function Menu to location 24 25 or 26 Q Is the Meridian available in different languages A It currently is available only in English However if you write the words and abbreviations that you want we will change the program There is a fee for this service Q need 2 different scales for the bargraph How do do it A The bargraph can be on the top orthe bottom line Use one range with the top line and one with the bottom line You will find it under Display Configuration Make sure the scale
47. ied by the bargraph on the bottom line The top line shows the digital level and the full scale of the bargraph The bargraph is on the bottom line and below that is the printed scale for the bargraph The bargraph pointer is updated ten times a second This makes it smooth continuous The numeric display is updated every second The instrument autoranges when it goes past full scale it will range up and when it gets to 80 of the lower scale it will range down The numeric display shows a maximum of 3 Significant figures The bargraph full scale figure on the top right indicates the full scale of the bargraph If it displays 1000 and the units are mRem h then full scale is 1000 mRem h The minor divisions would then be 800 600 400 and 200 mRem nh If the battery is low the word LBAT will flash on the top right of the display every 12 seconds men h 1000 RATE RANGE 1 Overrange If the rate value is too high it will show gt gt gt in the display It will show dashes if the rate display is over its range and waiting to change ranges The bargraph will also show gt when it reaches the right hand end of the display OVERRANGE INDICATION INTEGRATE The integrate display shows the numeric level and current status of the instrument on the top line On the bottom line it shows the time and the function of the two right hand keys The TIME softbutton will set the time and the Speaker button controls the status Re
48. in to reset You change the time by pushing the softbutton TIME The lt and T softbuttons change the time the RST softbutton resets the time to zero Push the OK softbutton when the time is what you want The Function Menus offers other choices besides changing the Mode Pushing MODE shows the Function Menu The choices are LCD for changing the LCD contrast and TC or Time Constantfor setting the speed of the bargraph This concludes the section on Quick Start See the sections that follow for a detailed description on all the functions available on the Meridian IV Operation Digital Display A TURN ON AND OFF Units The Meridian is easy to turn on just push the POWER button Pushing it once will turn the instrument on and pushing it again will turn the instrument off The first display will show the version number of the software 4 places of user text and the hours remaining on the battery Then the instrument will go into normal operation If the batteries are too weak it will not turn on If it tries to turn on and immediately turns off it may also be due to weak batteries The instrument will automatically turn off whenever the batteries are too weak to power the instrument If the instrument detects a fault the memory it will show FAILURE 1 in the display If this occurs see the section on Maintenance POWER MODE Printed The turn off display shows the hours remaining on the batteries If the instrument Bargraph Scal
49. its that you wantthe instrument to operate in The choices are cnt REM rad R Sv Bq Gy dis CPM CPS or User programmed This is the basic unit and does not include the prefix such as m or u For example the basic unit of a pancake GM detector is R and not mR It could also be in rad 16 Note the units in the space provided the worksheet and also the corresponding number from the table on the worksheet 2 Prefix Determine the prefix for the main rate range of the instrument If you want the instrument to work in uR h then the basic units would be p This assumes that the detector works in that range Don t try to set the instrument to read in when the basic units should be wR h For example the Pancake GM detector would want to read in mR h uR h would result in the display being too large a number and R would result in it being too small a number Note the prefix and the corresponding number from the table in the worksheet 3 Timebase Select the timebase of h m or s If you need another timebase use the User setting under Units Note the timebase and the corresponding number from the table in the worksheet 4 Calibration Factor and Exponent If the internal time base is set to CPM then determine the CPM prefix units timebase For example for a pancake detector that should read in mR h determine the CPM mR h This is 2100 CPM mR h If this number is below 1 CPM prefix units timebase or above 10 000 CPM pre
50. m the new value into that location using the Custom Settings Menu NOTE Some ofthe variables are only for the instrument some are for the detector and some are for the detector and each mode One is for the instrument and the mode 1 Disconnect the current detector during this operation if you are changing the high voltage and the new voltage may damage the detector 2 on the instrument with the MODE button pushed down If this does not result in the words Calibration 1 in the display then the Front Panel Calibration Adjust has been disabled and it is necessary to use the internal one The internal Calibration Adjust button is located through a small hole between the two battery holders in the battery compartment Push on this button while turning the instrument on The words Calibration 1 should be on the display 3 Using the 4 or T softbuttons repeatedly push them until Custom Settings 5 is visible Push the ok softbutton 4 The display will now show Loc Data on the top line and numbers on the bottom line These stand for location and data The location is the place in EEPROM memory that holds the data The data is the value that is stored in thatlocation Data and location have values from 0 to 255 The 3 digit number under Loc is the current location The 3 digit number under Data is the data for that location The right hand softbuttons change the numeric value of the data or location The lt softbutton will move the
51. meter and Integrator Setable integration time e Active calibration e Averaged reading with dynamically set time constant e Sealed metal case e Detector separates from readout e Cord wrap for detector cable MODEL 5085 MERIDIAN Health Physics Instruments lll Quick Start This section is a quick review of how to operate the instrument and how to change to the menu mode and functions Each one is discussed in detail in the individual sections Tum the instrument on and off by pushing the POWER button The normal operation starts after the battery check display The light button turns the light on and off The speaker button turns the beeper on and off Try both of them You will have to shield the display from room light to see the backlight but it is very visible in the dark If the display does not have a bargraph on the bottom line push MODE to display the Function Menu Then push the MODE softbutton the button with the speaker above it until RTE is on the line above MODE Then push the NEXT softbutton The display should now show mRem h or uSv h if in SI units on the top line and have a bargraph on the bottom line Next switch to the Integrate Mode to see what it will look like Push MODE to display the Function Menu Then push the MODE softbutton until INTG is on the line above MODE Then push the NEXT softbutton This is the Integrate Mode Push the INT softbutton to start running Push it again to stop and aga
52. n MODEL 5085 MERIDIAN Health Physics Instruments DETECTOR PLATEAU The High voltage is usually set by either using the recommended voltage from the manufacturer or by plotting the plateau All new instruments have been adjusted for operation on the plateau The voltage is supplied on the calibration sheet To plotthe plateau 1 Tum on the instrument with the MODE button pushed down If this does not result the words Calibration 1 in the display then the Front Panel Calibration Adjust has been disabled and it is necessary to use the internal one The internal Calibration Adjust button is located through a small hole between the two battery holders Push it while turning the instrument on The words Calibration 1 should be on the display 2 Pushthe softbutton until Det Setup 2 is in the display Then push the OK softbutton and the Meridian will resume normal operation with the radiation value on the top line and the calibration factor on the bottom line 3 Push the MODE button and then use J or softbuttons until the words High Voltage shows in the display Then push the OK softbutton The instrument will resume normal operation with the High Voltage on the bottom line 4 Exposethe detector in a fixed geometry to a medium intensity radiation source 5 instrumentis reading a value other than zero slowly lower the high voltage using the J or T softbuttons until the instrument reads zero If the instrument is r
53. n contains the values that are used in the Detector Setup Menu These correspond to the values in the 3rd and 4th column that show the range ofthe instrument The 5th column is the change in prefix up or down from the selected nominal value MODEL 5085 MERIDIAN Health Physics Instruments c Integrate Range The setup of the integrate range is similar to the rate range There are fewer choices in this mode 1 Calibration Factor and Exponent using Rate Range If the integrate range is in the same prefix units as the rate range then the same Calibration Factor can be used in calculating the integrate range Calibration Factor If the rate range is in mR h and the integrate range in mR then they are considered to have the same units Divide the Calibration Factor with Exponent by 60 if the internal timebase is in CPM and by 3600 if the internal timebase is in CPS This is the new calibration Factor and Exponent for the integrate range Mark the Units Prefix Calibration Factor and Exponent on the worksheet 2 Calculating the Calibration Factor and Exponent If the integrate range is not in the same prefix units as the rate range then you need to determined the basic units and prefix that you will want to use Calculate the basic prefix unit per counts For example if the GM pancake detector is to read in mR then do this in 2 steps First calculate the counts mR 2100 Counts Min mR h x 60 min hr 126 000 counts mR Then calc
54. ns on and off the Front Panel Calibrate Set to No if you want to have to open the instrument to change the calibration Set it to yes if you want access to the calibration adjustments through the front panel This can also be set by the menu Front Panel 7 of the Setup Menus CHECK TABLE Setting Adjust Adjust All Auto Power Front Panel Scaler modes 2 He Yes Yes No Yes Yes No MODEL 5085 Physics Instruments CHECK TABLE Setting Adjust Adjust All Auto Power Front Panel Scaler modes Calibrate 154 170 186 202 250 h Contrast Sets the contrast of the instrument This is normally set with the Contrast adjustment LCD softbutton It is preset to 160 in the Factory Setting If this is incorrectly set it may be impossible to read the LCD If that is the case use the Emergency Contrast Adjustment i CPM CPS Intemal Timebase This selects the internal timebase of the instrument There are 2 choices CPM Counts per minute or CPS Counts per second If this is set to CPM and then programmed with the Instrument Setup Detector Setup or Factory Setup menus the instrument will be in conventional units and the rate range will probably read in mR h If itis setto CPS and then programmed with one ofthe 3 Setup menus the instrument will be in SI units Setthis to 0 for Conventional Units and 1 for SI units or use one of the choices in the Setup Menus There is another re
55. nt it to range down during a momentary dip in radiation In this case increasing the Range Down Time would be useful Set both of these in the Custom Setting Menu 3 Modes The modes can be turned on or off This allows the instrument to function in whatever capacity you want If you do not need a scaler or an integrate range turn them off using the Mode Lockout in the Custom Settings There is also a User Mode that can be programmed in any rate units you want Use the Mode Lockout in the Custom Settings Mode to tum on this mode Then program it in the Setting Up a New Detector section for the units prefix etc just the same as the rate range The CPM S range can also be changed into any units It does not have to be used for CPM S 4 Internal Time Base The internal timebase of the Meridian can be in Counts per Minute or in Counts per Second In general CPM is used with conventional units and CPS is used with SI units See the section on Programming Internal Timebase for more information 5 Detector There are a maximum of 3 detectors that can be used with the Meridian if each needs its own set of settings Of course any number can be used with the same settings For example many GM detectors use the same high voltage and all should be used on the CPM S range However all would not read correctly with the Rate Range To add detectors you will need to either make a DET Function Menu or Soft Button In addition you will need to set
56. nts MODEL 5085 MERIDIAN Specifications MECHANICAL E Size overall 8 55 in 22 cm W x 9 5 in 24 L 17 5 in 45 cm Gasketed splashproof aluminum enclosure Top panel is milled and anodized with nonerasable nomenclature Bottom painted LCD window is acrylic Weight 20 5 Ib 9 3 kg with batteries External controls 4 pushbuttons Power Mode Speaker and Light Power button when held down for 5 seconds resets the microprocessor Internal controls 1 push button for entry into calibrate mode Internal construction Circuit board hinges for easy access Batteries are mounted on an aluminum panel in nylon holders ICs are socketed All components are standard types ELECTRICAL Detectors Bf3 Standard He3 available Display 2 line x 20 character alphanumeric supertwist LCD with backlight Contrast adjustable from front panel Audio Built in piezo beeper at 2 4 kHz High voltage Adjustable from 300 to 2000 Volts Batteries 6 AA cells for 100 hour life Battery condition displayed at tum on and turn off Low battery warning during operation Instrument will automatically turn off when batteries are too low for proper operation May be set for auto turn off Calibration and parameter storage Data stored in permanent memory for minimum of 40 years Batteries not required for storage OPERATIONAL Modes 2 modes available Rate and Integrate others programmable Calibration setup and maintenance mod
57. o the instrument revolve around the buttons This includes both the Quick keys and the Function Menus They both can be modified to meet your needs The Quick keys are the buttons that are on the right hand side of the panel and are active during CPM S Rate and User Modes These are also referred to as the and A Quick keys In the Meridian the quickeys are predefined as the light and speaker buttons and they are factory set to Beeper and Light which are probably the most generic uses of the controls on a survey meter There are 7 other choices that are available If you do not need the light or beeper then you may consider using either button for either the Range Hold Hold or contrast The other options are listed under the or A Buttons in Custom Settings There is 1 Function Menus with the factory settings If you need more capability such as range hold you could change up to 3 Function Menus The location of the functions within the Function Menu can also be changed Each of the three locations above the three right hand buttons is available for any of the functions If you are left handed and use the MODE button frequently consider moving it to the left hand side of the instrument Changing location 18 from 5 to 10 and location 20 from 10 to 5 in the Custom Menu will swap the MOD and We usually put the most used functions on the first menu 2 Display The display is the other part of the instrument that can be customiz
58. of the CPM or CPS range can be changed but it may be confusing to a user and difficult in calibration However it may be changed if necessary The scaler does not have a calibration In the following descriptions we will use a GM Pancake Detector as an example even if itis not the same detector as supplied with the instrument a Basic Detector Information 1 Detector 1 2 or 3 The Meridian can change between detector 1 2 or 3 This is done using the Function Menus The Detector that is in use or selected is the detector whose variables will be changed If there is no DET function in the Function Menus then there is only one detector detector 1 2 CPM or CPS Internal Timebase Turn the instrument on and look at the first word on the display If itis HPI then the instrument has the internal timebase set to CPM If itis HPls then the internal timebase is in CPS To change the timebase see the section on Programming Internal Timebase When shipped from the factory the internal timebase is in CPM for conventional units and the CPS for SI units 3 Detector Sensitivity Obtain the sensitivity of the detector from the specification sheet The example detector has a sensitivity of 2100 CPM mR h 4 Deadtime The Deadtime value should be listed in the detector specification sheet Note this value on the worksheet The Example GM detector has a deadtime of 100 uSec or 100 x 105 Sec b Rate Ranges 1 Units Determine the rate un
59. op scale it may be better to limit use of that top scale Likewise at very low count rates if the bottom scale will be at nearly full scale from background then that scale is useless This setting helps to determine the minimum and maximum scales to use For defaults the Range Low Limit can be setto 0 and the Range Hi Limit can be set to 5 This can be corrected interactively in actual use in the Detector Setup Menu To understand the table below imagine that the basic units and prefix which have been set from the above steps are in the three places marked 0 in the column marked Range With Prefix Units The three spaces marked 1 in Range with units would have the next lower prefix and the 3 spaces marked 1 would have the next higher prefix The Meridian will automatically select the higher and lower prefix but you have already setthe starting point from the prefix units timebase settings made in the above steps There are 2 reasons for setting an upper range The firstis that when the instrument detects saturation or too many counts it will make the Range Hi Limit the range that is shown with the overrange indicators The other reason is to keep from switching to a high range if only a small portion of it can be used because of saturation or deadtime losses The maximum level has been calculated above Find which range would be the maximum range based on the above calculations Setthe Range Hi Limitto the next higher range Note the valu
60. or each mode 8 DET Detector The instrument will accept 3 detectors This controls which set of detector constants are in effect This effects the calibration high voltage deadtime display etc The choices are 1 Use the constants for Detector 1 2 Use the constants for Detector 2 3 Use the constants for Detector 3 The instrument will prompt the user to remove the old detector and to install the new detector 9 HLD Hold This puts the instrument on hold HOLD is displayed on the top right hand corner of the display The numeric number is held but the bargraph continues to function The choices are ON Freezes the numeric display OFF Normal operation 10 DIV Divider for Beeper The counts from the detector can be divided by 1 8 64 or 2048 before they are sent to the beeper This is useful where the beeper may otherwise be saturated or sound like it is on continuously The choices are 1 Counts 8 Counts 64 Counts 2K Counts 13 11 CAL Calibrate Mode This mode is used to putthe instrument into the Calibrate Mode See the section on Calibrate Mode for more information The choices are OFF Normal operation ON Instrument in Calibrate Mode PROGRAMMING The following sections discuss programming the instrument It is important to understand the setup ofthe instrument before actually performing it T Instrument and Detector Settings There are 2 basic kinds of settings in the Meridian The first is the Instrument
61. ormat down 1 decade so that a prefix change will not occur when the value goes below 100 For example instead of going from 1 00 mR h to 999 uR h the display would go from 1 00 mR h to 999 mR h On the next lower decade the display would change the prefix 4 This is a combination of 2 and 3 where the span of one prefix will be extended up and down 1 decade This is usually the recommended setting DISPLAY TYPE Engineering format Down 1 decade MODEL 5085 MERIDIAN Health Physics Instruments q Dt On Off Use the same table as in Mode Lockout This controls if the deadtime is turned on or off for each Mode If itis set to ON then the deadtime is turned on The common setting is 10 which turns the deadtime correction on only for the Rate and Integrate modes r Exponent This is the value of the Exponent in the instrument It is a positive and negative number that rolls negative at 255 Thus 0 is zero 5 is 5 and 252 is 4 Itis best set in the Calibrate or Detector Setup Menu o0 3 1 0 48 7 9 o s Front Panel Calibrate See Check t Function Menus There are 12 different possibilities for the Function Menus These are the softbuttons 1L refers to the 1st Function Menu after you push the MODE button and the L refers to the left hand softbutton really the MODE button C is the center softbutton really the button and R is the right softbutton really the A button There are therefore 3 pos
62. out This determines which modes can be displayed Set it to off if itis a mode you do not want Setit to on if itis a mode you want to be able to choose with the MOD softbutton A common setting is 27 which turns on all the Modes except the User Mode The Current Mode should be set to one of the modes that is on MODE LOCKOUT AND DT ON OFF TABLE CPM S RATE USER INTEGRATE SCALER off 0 fof MODEL 5085 MERIDIAN Health Physics Instruments x Power Off See Check y Power Time This is the timer for the automatic tum off Itsets in increments of 25 5 seconds and can be set from 0 to 255 Itis preset to 255 which is 108 minutes This means that the instrument will automatically turn off in 108 minutes after the last button has been pushed z Power User 1 Thru 3 This allows any 3 characters to be displayed on the right hand side of the LCD at turn on See the ASCII table under User below for the setting of the character Power User 1 is the left hand character aa Prefix The prefix is the starting point for all the modes except the Scaler PREFIX TABLE fo ass Oooo prew M mes p pk 9 6 s mmi i s me bb Range Hi Lo Limits This sets the limits of the display both upper and lower limits It has the value from 119 to 136 with 128 in the center Set this to keep the detector from being too sensitive and to keep it from going into a high s
63. peatedly pushing the Speaker button will cycle through integrate INT stop STP and reset RST When the instrument is running the numeric value and the time will update every second When itis stopped the display is frozen When it is reset the integrated value is reset and the time is preset Health Physics Instruments The time can work both as a timer or as an integration timer If the time is set to 0 then the timer will count up If itis set to some value other than zero then it will count down when it gets to zero it will stop the instrument and beep if the beeper is turned on If the battery is low the word LBAT will flash on the top right of the display every 12 seconds 0 nRem RESET 00 01 00 TME INT INTEGRATE RANGE SETTING THE TIME The time can be set in the integrate mode Push the TIME softbutton when in this mode to access the Time Setting Mode The left side of the display shows the time in HOURS MINUTES SECONDS The right hand top shows the word SETTIME to let you know that this is the Set Time Mode The bottom left softbutton is RST This resets the time to 00 00 00 The lt softbutton moves the cursor one digit to the left The T softbutton increments the digit that has the cursor under it Move the cursor to the digit you want and increment it to the number you want When the time is set to the correct value push the OK softbutton to get back to the mode If the time is set to a number other than zero then the
64. ption of Custom Settings The following descriptions are in alphabetical order a Button This selects the function of the button AND A QUICK KEY BUTTON DEFINITIONS Buzzer Divider Sets buzzer divider Detector Set Chngs to det 1 2 or3 Mode Change changes the Mode b Button This selects the function of the A button and has the same choices as the button c Adjust See Check d Bargraph Type This is the full scale value of the bargraph It allows four choices for full scale on the bargraph This will not change the calibration of the instrument but will alter when the range change occurs The Digital display will change ranges to keep the bargraph on scale 10 Setting 1 is usually used for full scale however for different applications any of the others are equally applicable The 5 decade log display is a quasi log with linear values between the decades Each decade is represented and each decade is linear This mode will make the digital display change ranges the same as type 1 Change the bargraph scale inside the instrument located above the display under the window if you change this value The log bargraph is set with the Range Lo Limit as the beginning ofthe range BARGRAPH TYPE 21 1 10 100 1000 1K 25 2 5 25 250 2 5K 5 5 50 500 5085 5 109 Beeper Divider The beeper divider divides the pulses from the detector before sending them to the beeper This is useful with detec
65. r softbuttons the normal function menus will be displayed when you push the MODE button 5 Inthe Integrate Range the softbuttons are already in use Pushing MODE repeatedly will show the factor followed by the normal Function Menu The factors is adjusted just like the ones in the Rate Mode 6 There are 3 adjustments to be made the Calibration Factor the Exponent and the Deadtime The Calibration Factor and Exponent form a number that determines the value on the display They should be thought of as one number in exponential form Changing the Calibration Factor and Exponent changes the value on the display at all doserates Increasing the number will increase all the readings in that Mode Decreasing it will decrease the reading The Deadtime corrects for deadtime losses that occur in all pulsed detectors The Deadtime number will effect the readings at high count rates Atlow count rates the change is insignificant MODEL 5085 MERIDIAN Health Physics Instruments 0 mRem h 1000 FACTOR1 00E 04 7 CALIBRATE DISPLAY CALIBRATION EXPONENT AND DEADTIME FACTORS The Calibration Exponent and Deadtime Factors are all used in the Calibration of the instrument The Calibration and Exponent are in reality one number This number is used to increase and decrease the value of the calibration Ifthe Calibration is 10 too low then it is necessary to increase the Calibration Factor 10 The combination of Calibration Factor and Expon
66. rk To recover from this test push the power button down for 10 seconds to reset the instrument or on the RS232 connection type GO MODEL 5085 MERIDIAN Health Physics Instruments 2 High Voltage Calibration The high voltage displays on the Meridian are actually measured rather than just calculated This measurement system may need calibration Connect a high voltage high impedance meter with gt 10 000 megohm input resistance to the detector connector on the front panel The meter should be capable of measuring 2200 Volts DC 1 the instrument in the Setup Menu and change it to the HV Calibrate 6 Menu Press ok to change into the HV calibrate display 2 Measure the high voltage with the external voltmeter 3 Using the T and J softbuttons change the Cal number until the HV is as close as possible to the measured high voltage 4 Pushthe ok softbutton to save the value Push the POWER button if you do not want to change the calibration 3 Failure in Display If the display says FAILURE then the EEPROM has failed This may mean that is it corrupted or that it is not working In any case you should try to reprogram it which may preserve many ofthe settings 1 the instrument on after the display shows Failure 1 push the internal CAL button on the back of the main circuit board Itis accessable through a small hole between the battery holders The display will change to the Setup Menu 2 Advance the menu
67. s in the display then push the OK softbutton The Meridian will resume normal operation with the count rate value on the top line and the calibration factor on the bottom line 3 The softbuttons change the numeric value in the bottom line of the display The lt Softbutton will move the cursor over 1 place and the softbutton will increase the value of the number positioned over the cursor Using the two buttons you can change the value of the displayed item in the bottom line The value in the top line will change along with the new value in the bottom line 4 Rate and CPM modes the item on the bottom line can be changed by pushing MODE then the J or softbuttons until the item description is what you want to change or do Then push the MODE button to return to the MODEL 5085 MERIDIAN Health Physics Instruments calibration If you do not push the J or T softbuttons the normal function menus will be displayed when you push the MODE button In the Integrate Range pushing MODE repeatedly will show the factors followed by the normal Function Menus These factors are adjusted just like the ones in the CPM and Rate Modes After changing the items to the values that you want you can either turn the instrument off or select Norm Operation from the choice of setup menu items 15 SETTING UP A DIFFERENT DETECTOR The detector is changed to a different type than the Meridian was ordered with it is necessary to configure
68. s are in place on top of the LCD When use the highest range and the reading is about mid scale it then jumps off scale can t get it to read at the top end of the scale Why not A There are 2 reasons for jumping off scale If the instrument thinks that the detector is in saturation or if the instrument thinks that there are too many counts for the detector it will make it go off scale Check the saturation setting it may be too high The instrument uses the deadtime setting to calculate how high it should go before showing off scale It does this even though the deadtime is turned off To remove the limits set the saturation and deadtime to 0 This will turn them both off but it may change the calibration MODEL 5085 MERIDIAN Health Physics Instruments 27 l APPENDIX A WORKSHEET DETECTOR SETUP Detector Type laDetwilbe DET1 DET2 DET3 Detector Name Detector Serial Number 1b Internal Timebase 1 Sensitivity i e CPM mR h Use Tables below for determining the settings You will need both the setting and the value UNITS TABLE Units dis CPM CPS user 1 thru 5 O O CPs 1d deadtime RATE RANGE Units Setting 2b Prefix Setting 2c Timebase Setting 2d1 Calculate CPM S per prefix units timebase 2d2 Recriprocal of step 2d1 Calibration Factor Exponent EXT EDGE ing 0 mne 2e2 Max Level in display 2f Max Range Range Hi Limit
69. s using the T or J softbutton until the displays shows the Custom Set 3 Then push OK Push the POWER button to change the cursor to the Data Use the and T softbuttons to change the Data to 26 Then push the POWER button then the MODE button twice 3 Ifthe display shows a normal turn on then the EEPROM was only corrupted a little and it would be wise to check the calibration and operation of the instrument If it shows a Failure 1 then the EEPROM is defective and should be replaced 4 Installing a New EEPROM When installing a new EEPROM itis necessary to program it to the default values It will show Failure 1 in the display until itis programmed 1 Turn the instrument on after the display shows Failure 1 push the internal CAL button on the back of the main circuit board Itis accessable through a small hole between the battery holders The display will change to the Setup Menu 2 Advance the menus using the T or J softbutton until the display shows the Factory Set 9 Then push OK answer the question CPM answer if you want CPS or SI units and then Yes to Are you sure It will take 30 seconds to program the entire EEPROM 3 After itis done programming push the Mode button to resume normal Operation 4 Check the new EEPROM by turning the instrument on and off If it turns on without the failure warning then it has been programmed 5 instrument will now need to be completely recalibrated 5
70. sible Function Menus each with 3 possibilities 23 If a complete function menu is programmed with 0 in all three locations then the previous Function Menu will be the last one displayed FUNCTION MENU SOFTBUTTON DEFINITIONS None Display will be blank and Softbutton will do nothing Light on off timed Buzzer on off soft ime Constant slow medium fast ontrast adjustment ange Hold which keeps the same range C 16 Hold Freezes the numeric display 8 9 O Beeper Divider Set to 1 8 64 or 2048 counts beep Detector number Changes the number of the current detector Deadtime in out Choose for each mode Mode selects from CPM S Rate User Intgrt Scaler Calibrate Changes to calibrate mode Window Turns window on or off 1 12 u High Voltage This is the actual high voltage setting Set it from 0 to 255 The value of the high voltage is 9 8 volts per unit This is an approximate setting Check the actual setting for each detector in the Calibration or Setup Menu HIGH VOLTAGE SETTINGS 9 8 Volts unit of setting This table has some common settings for high voltage Vols 4 7 1 eju High Voltage Cal This is a factor that calibrates the high voltage displays in the Meridian It does not change the value of the actual high voltage This is best set in the High voltage Calibrate Setup Menu Its nominal value is 90 See the Maintenance section for details on setting this variable w Mode Lock
71. time off The formula is below There are 4 possibilities with and without deadtime and CPM and CPS timebases Choose the correct one for your application The Deadtime is usually turned on for Rate Ranges Deadtime is in seconds MODEL 5085 MERIDIAN Health Physics Instruments 15 usec is 15 x 10 Sec Note the values on the worksheet For example with a CPM timebase and the deadtime of 100 uSec turned on the highest level for the GM pancake detector would be 204 100 x 109 2 040 000 CPM CPM Timebase Deadtime off Highest level CPM 46 3 deadtime Deadtime on Highest level in 204 deadtime CPS Timebase Deadtime off Highest level CPS 772 deadtime Deadtime on Highest level CPS 3 4 deadtime 2 Calculate the maximum level that can be displayed on the instrument by multiplying the maximum level times the Calibration Factor Note the value on the worksheet Max Level in Units Max Level in CPM CPS x Calibration Factor For the example this would be 2 040 000 x 4 76 x 1 971 mR h This figure can be helpful in determining the maximum range that can be used with the detector 6 Determining the Minimum and Maximum Ranges Now it is necessary to determine the minimum and maximum range The instrument will calculate and display the appropriate value Athigh doserates when the detector becomes saturated the display will instantaneously show full scale If the instrument can use only a small portion of the t
72. time will count down and stop at zero If the time is set to zero then it will start counting up and will continue up to 99 59 59 whereby it will roll over to 00 00 00 and continue counting up If you set 68 minutes in the display when you change back to the Integrate Mode the time will be recalculated to the correct hours minutes seconds In this case it would show 01 08 00 which is the same as 68 minutes This works for seconds also The cursor will be on minutes when entering the Time Setting Mode because most settings are in minutes VI Operational A DETECTOR CONNECTION The detector is connected to the instrument through the MHV located on the top panel B LOW BATTERY When the battery is low and has less than 8 hours remaining the word LBAT flashes in the upper right hand corner It flashes every 12 seconds Itdoes not flash in the Function Menus C BATTERY CHANGE When the batteries are too low as indicated on the tum on menu or the turn off menu then it is time to change them The instrument uses 6 type AA penlight ANSI L40 IEC LR6 cells These can be any type of battery except lithium If you want to use lithium use 3 ea 3 volt lithium AA cells and 3 dummy AA batteries The hours that are displayed at turn on and turn off are calculated for alkaline batteries Carbon zinc batteries will not give the correct time The batteries are located inside the instrument Access is by removing the bottom case To c
73. tors that have higher count rates such as scintillators Itis hard to distinguish changes in beep rate when the beeper is on almost all of the time Setting the divider to a higher number will reduce the number of beeps and make changes more apparent BEEPER DIVIDER 0 qm 10 Jpe4 O 1 h 298 f Cal High Low This is the value of the Calibration Factor all modes except the scaler It is set for each detector and each mode It is bestset in the Calibrate or Detector Setup Menu It is in reality a two byte HEX number The High byte and low byte make up the complete calibrate number It is set from 100 to 999 This is 100 times greater than the value in the display in the Calibrate Mode because the program takes care of the difference To set it to 1 00 in the Calibrate Display set Cal High to 0 and Cal Low to 100 To setit to 5 00 in the Calibrate Display set Cal High to 1 and Cal Low to 2440 g Check This location contains the settings for several variables ADJUST on and off for scaler and for other ranges No tums the adjust off and Yes turns it on This can also be set by the menu Front Panel 7 of the Setup Menu POWER OFF Tums the power off automatically after the time specified in Power Off Time Set to no to tum off the automatic power off If you want it to tum off automatically set it to yes This can also be set by the menu Front Panel 7 of the Setup Menus FRONT PANEL CALIBRATE Tur
74. turned on and off in the Setup Menu is under Front Panel 7 It has 2 choices the first is for all modes and the second is for just the scaler mode b Using Adjust The display has the function name in the upper left hand the value of the function in the center of the display and the count rate display in the upper right The Count rate display is the number of counts in 0 1 second The NXT softbutton changes to the next function and the 4 and T softbuttons will increment or decrement the value of the function Hold them down until the function is at the desired level The Mode button will return to normal operation HV or High voltage will change the High Voltage The display number will bounce about 30 volts Be careful not to increase the high voltage above the limit of the detector DISCR or Discriminator is the setting for the discriminator Itcan be set from 0 to 255 but is linear from 0 to 100 11 CUSTOMIZING THE MERIDIAN The Meridian may be customized by changing the variables The operation of the instrumentis very programmable and is based on the Cypher Survey Meter which is a very programmable instrument The section on the Custom Menu describes each of the variables The Description of Custom Setting Menu shows all the possible settings for the Meridian We offer the following tips and suggestions on how to change the instrument to meet your particular needs 1 Buttons Probably the most useful changes t
75. ulate the mR counts by taking the reciprocal 1 126 000 000 007 93 or 7 93 x 10 7 93 x 10 is the Calibration Factor and Exponent 7 93 is the Calibration Factor and 6 is the Exponent Mark the Units Prefix Calibration Factor and Exponent on the worksheet 3 Range High and Low Limits Set the Range High to 8 Set the Range Low to 4 This range will usually be low enough to change with the first few counts If you want itto be less sensitive then change to 3 or 2 d Detector Settings The Detector needs its own settings of High Voltage Discriminator Gain and Saturation to function 1 High Voltage The High voltage is usually set by either using the recommended voltage from the manufacturer or by plotting the plateau Either method will work To plotthe plateau 1 Expose the detector in a fixed geometry to a medium intensity radiation source 2 Slowly raise the high voltage until the detector begins to count You may need to adjustthe discriminator before this step 18 3 Raise the high voltage in uniform steps of 50 volts At each step note the f Programming the Setup Value radiation intensity on the CPM S range Do not go above the maximum The values on the worksheet may be programmed into the instrument in either of voltage for the detector 2 ways The first and easiest way is to use the Detector Setup Menu This is an interactive mode that shows the count rate as well as the settings for e
76. ype 2 Those that do not change with the Mode and are considered part of the detector Examples are the High Voltage The Discriminator and the Deadtime MODEL 5085 MERIDIAN Health Physics Instruments 4 Internal Timebase The Meridian has two choices for an internal timebase CPM Counts Per Minute or CPS Counts Per Second This changes the basic units that the instrument works in internally It actually calculates the values in 1 CPS or 01 If itis setto CPM in the Factory Setup menus the instrument will be in conventional units and the rate range will probably read in mRem h If itis set to CPS then the instrument will be in SI units The CPM or CPS ranges have their own calibration and can be programmed in any units desired It is designed to be used with or CPS and that is the nomenclature in the Function Menu If the instrument is in CPM and the Calibration Factor and Units for that range are changed to read in CPS instead of CPM then the reading will not be exactly correct The Calibration Factor has only 3 places of accuracy Thus 100 CPS may read only 99 CPS One ofthe choices with the MODE softbutton in the Function Menu during normal operation is CPM If you wantthis to be CPS then you must choose the CPS internal timebase If you want itto be CPM then you must choose the CPM internal timebase Changing this will also change the calibration of the Rate Range the Integrate Range and the User Range if used

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