Fluke 945A User Manual

Installation, Operation, and
Maintenance
Instruction Manual

Wide-Range Area Monitoring
System

Model 945A

April, 2006, P/N 945A-1, Rev. 13
©2006 Fluke Corporation, All rights reserved. Printed in U.S.A.
All product names are trademarks of their respective companies

Fluke Biomedical

Radiation Management Services

6045 Cochran Road
Cleveland, Ohio 44139

440.498.2564

www.flukebiomedical.com/rms

ii

PROCEDURES, WARNINGS, AND CAUTIONS

The equipment described in this manual is intended to be used for the detection and measurement of
ionizing radiation. It should be used only by persons who have been trained in the proper interpretation of
its readings and the appropriate safety procedures to be followed in the presence of radiation.

Although the equipment described in this manual is designed and manufactured in compliance with all
applicable safety standards, certain hazards are inherent in the use of electronic and radiometric
equipment.

WARNINGS and CAUTIONS are presented throughout this document to alert the user to potentially
hazardous situations. A WARNING is a precautionary message preceding an operation which has the
potential to cause personal injury or death. A CAUTION is a precautionary message preceding an
operation which has the potential to cause permanent damage to the equipment and/or loss of data.
Failure to comply with WARNINGS and CAUTIONS is at the user's own risk and is sufficient cause to
terminate the warranty agreement between Fluke Biomedical RMS and the customer.

Adequate warnings are included in this manual and on the product itself to cover hazards that may be
encountered in normal use and servicing of this equipment. No other procedures are warranted by Fluke
Biomedical RMS. It shall be the owner's or user's responsibility to see to it that the procedures described
here are meticulously followed, and especially that WARNINGS and CAUTIONS are heeded. Failure on
the part of the owner or user in any way to follow the prescribed procedures shall absolve Fluke
Biomedical RMS and its agents from any resulting liability.

Indicated battery and other operational tests must be performed prior to each use to assure that the
instrument is functioning properly. If applicable, failure to conduct periodic performance tests in
accordance with ANSI N323-1978 (R1983) Radiation Protection Instrumentation Test and
Calibration, paragraphs 4.6 and 5.4, and to keep records thereof in accordance with paragraph 4.5 of
the same standard, could result in erroneous readings or potential danger. ANSI N323-1978 becomes,
by this reference, a part of this operating procedure.

READ YOUR INSTRUCTION MANUAL

iii

iv

Table of Contents

Page

SECTION 1 - INTRODUCTION........................................................................................................................... 1-1

G

ENERAL DESCRIPTION....................................................................................................................................... 1-1

Ion Chamber Detector/Preamplifier, Model 977-210....................................................................................... 1-1

Specifications, Ion Chamber Detector............................................................................................................... 1-2

Specifications, Preamplifier, Model 977-210-95 ............................................................................................... 1-2

Universal Digital Ratemeter, Model 946A-200................................................................................................. 1-4

Application ..........................................................................................................................................................................1-5

Specifications .......................................................................................................................................................................1-5

Auxiliary Equipment........................................................................................................................................... 1-6

SECTION 2 - RECEIVING INSPECTION AND STORAGE............................................................................ 2-1

R

ECEIVING INSPECTION....................................................................................................................................... 2-1

S

TORAGE ................................................................................................................................................................. 2-1

SECTION 3 - INSTALLATION............................................................................................................................ 3-1

I

NSTALLATION ....................................................................................................................................................... 3-1

Detector Mounting............................................................................................................................................... 3-1

UDR Mounting .................................................................................................................................................... 3-1

E

LECTRICAL INTERFACE..................................................................................................................................... 3-2

S

ET-UP...................................................................................................................................................................... 3-6

SECTION 4 - OPERATION/FUNCTIONAL DESCRIPTION.......................................................................... 4-1

O

PERATION............................................................................................................................................................. 4-1

D

ETECTOR OPERATION........................................................................................................................................ 4-1

UDR O

PERATION / FUNCTIONS........................................................................................................................... 4-3

Normal Operation ............................................................................................................................................... 4-3

WARN/HIGH Alarms......................................................................................................................................... 4-3

Range Alarm........................................................................................................................................................ 4-3

Fail Alarm ............................................................................................................................................................ 4-4

Check Source ....................................................................................................................................................... 4-4

F

IRMWARE VERSION............................................................................................................................................. 4-4

O

PERATIONAL MODES.......................................................................................................................................... 4-5

Rate Mode (Normal Operation)......................................................................................................................... 4-5

Data Entry Mode................................................................................................................................................. 4-5

Alarm Inhibit....................................................................................................................................................... 4-5

Check Source ....................................................................................................................................................... 4-5

Maintenance Mode.............................................................................................................................................. 4-6

Auto Zero Mode................................................................................................................................................... 4-7

Loop Test Mode................................................................................................................................................... 4-7

A

LARMS................................................................................................................................................................... 4-7

Alarm Logic ......................................................................................................................................................... 4-7

Manual Reset....................................................................................................................................................................... 4-8

Auto Reset............................................................................................................................................................................4-8

HIGH Alarm........................................................................................................................................................ 4-8

WARN Alarm ...................................................................................................................................................... 4-8

RANGE Alarm..................................................................................................................................................... 4-9

v

Table of Contents

Page

FAIL Alarms........................................................................................................................................................ 4-9

Low Signal Failure..............................................................................................................................................................4-9

Auto Zero Failure .............................................................................................................................................................4-10

High Voltage Failure.........................................................................................................................................................4-10

Loop Failure......................................................................................................................................................................4-10

Power Failure.................................................................................................................................................................... 4-10

MPU Failure ......................................................................................................................................................................4-10

POWER UP PROCEDURE ..................................................................................................................................... 4-11

H

OW TO ENTER SETPOINTS............................................................................................................................... 4-11

S

ETPOINT DESCRIPTIONS................................................................................................................................... 4-12

HIGH Alarm Limit............................................................................................................................................ 4-12

WARN Alarm Limit.......................................................................................................................................... 4-12

Overrange Limit................................................................................................................................................ 4-12

Underrange Limit.............................................................................................................................................. 4-13

Analog Full Scale............................................................................................................................................... 4-13

Calibration Factor............................................................................................................................................. 4-13

Analog Low Scale .............................................................................................................................................. 4-13

S

ET POINT ERROR CODES.................................................................................................................................. 4-13

A

NALOG OUTPUT................................................................................................................................................. 4-14

V

ICTOREEN COMMUNICATIONS LOOP............................................................................................................ 4-15

(P

REAMPLIFIER SWITCH & JUMPER SETTINGS) ........................................................................................... 4-15

D

IGITAL RATEMETER CONFIGURATION OPTIONS ....................................................................................... 4-16

UDR S

WITCH AND TABLE SETTINGS................................................................................................................ 4-16

Jumper Selectable Options............................................................................................................................... 4-16

UDR Function Switch / Function..................................................................................................................... 4-17

E

RROR CODES ...................................................................................................................................................... 4-17

P

REAMPLIFIER/UDR DIAGNOSTIC LED INDICATORS.................................................................................. 4-18

977-210 Detector/Preamplifier ......................................................................................................................... 4-18

946A-200 UDR................................................................................................................................................... 4-18

F

UNCTIONAL DESCRIPTION............................................................................................................................... 4-19

Detector and Preamplifier ................................................................................................................................ 4-19

Universal Digital Ratemeter (UDR), Model 946A-200................................................................................... 4-23

Main Circuit Board...........................................................................................................................................................4-23

Microprocessor............................................................................................................................................................. 4-23

Reset Circuitry.............................................................................................................................................................. 4-28

Clocks ............................................................................................................................................................................4-28

NMI Clock..................................................................................................................................................................... 4-28

Write Cycle Clock.........................................................................................................................................................4-28

Address Drivers............................................................................................................................................................ 4-28

Data Transceivers.........................................................................................................................................................4-29

Control Signal Buffer................................................................................................................................................... 4-29

Address Decoding.........................................................................................................................................................4-29

PROM............................................................................................................................................................................ 4-30

RAM ..............................................................................................................................................................................4-30

E2............................................................................................................................. ...................................................... 4-30

Read - Write Cycles..................................................................................................................................................... 4-31

Write Register Decoding..............................................................................................................................................4-31

Counter Control (Write Only)................................................................................................................................ 4-31

Relay Control Register (Write Only)......................................................................................................................4-32

Bargraph (Write Only)............................................................................................................................................4-32

Status Indicators (Write Only)................................................................................................................................4-33

Display Control (Write Only)..................................................................................................................................4-34

Digital to Analog Converter and Output Circuitry (Write Only)............................................................................4-35

vi

Read Register Decoding...............................................................................................................................................4-35

Data Entry (Read Only)...........................................................................................................................................4-36

Sensitivity Select (Read Only).................................................................................................................................4-36

Switch Inputs............................................................................................................................................................ 4-37

Option Board Bus.........................................................................................................................................................4-38

Relay Circuit Board.......................................................................................................................................................... 4-38

Front Panel Circuit Board ...............................................................................................................................................4-38

Circuit Description (Front Panel Circuit Board).......................................................................................................4-38

Power Supply.....................................................................................................................................................................4-40

Optional Circuit Boards...................................................................................................................................................4-40

SECTION 5 - MAINTENANCE............................................................................................................................ 5-1

M

AINTENANCE 946A-200...................................................................................................................................... 5-1

R

EPLACEMENT PARTS ...................................................................................................................................... 5-1

M

AINTENANCE 977-210......................................................................................................................................... 5-1

R

EPLACEMENT PARTS ...................................................................................................................................... 5-1

SECTION 6 - CALIBRATION.............................................................................................................................. 6-1

C

ALIBRATION (INCLUDES FACTORY CAL., TEST, & TERMINATION PROCEDURES) ........................................... 6-1

SECTION 7 - TROUBLESHOOTING.................................................................................................................. 7-1

T

ROUBLESHOOTING.............................................................................................................................................. 7-1

Troubleshooting / Adjustments.......................................................................................................................... 7-2

Error Codes E0011 & E0012.............................................................................................................................. 7-2

Auto-Zero Adjustment Procedure..................................................................................................................... 7-3

Analog Output Adjustments (946A UDR) ........................................................................................................ 7-5

0 to 10 Volt, zero, and span adjust..................................................................................................................... 7-5

4 - 20 mA Analog Output Adjustment............................................................................................................... 7-6

977-210 Detector Analog Output Adjustments................................................................................................. 7-6

APPENDIX A. - CONNECTOR DESIGNATIONS ......................................................................................... 8-1

APPENDIX B. - APPLICABLE DRAWINGS.................................................................................................. 9-1

APPENDIX C. - BILL OF MATERIALS........................................................................................................ 10-1

APPENDIX D. - COAXIAL CABLE TERMINATION INSTRUCTIONS.................................................. 11-1

APPENDIX E. - COMMUNICATIONS OPTION BOARD MANUAL....................................................... 12-1

APPENDIX F. - SUPPLEMENTAL DATA (CUSTOMER SPECIFIC)...................................................... 13-1

vii

List of Figures

Page

Figure 1-1. Detector Energy Response........................................................................................... .............................. 1-3

Figure 1-2. Front Panel, Model 946A-200 Universal Digital Ratemeter......................................................................1-6

Figure 4-1. Detector Electronics Block Diagram........................................................................................................4-22

Figure 4-2. Page 1 of 3. Block Diagram - Main Circuit Board .................................................................................. 4-24

Figure 4-3. Read / Write Timing Diagram..................................................................................................................4-27

Figure 4-4. Write Cycle Clock Timing Diagram........................................................................................................ 4-28

Figure 4-5. Front Panel, Model 946A-200.................................................................................................................. 4-39

List of Tables

Page

Table 3-1. Rear Panel Connections .............................................................................................................................3-2

Table 3-2. Connector P1 - Input/Output......................................................................................... ............................. 3-3

Table 3-3. Connector P2 - Detector Connector ........................................................................................................... 3-4

Table 3-4. Connector P3 - Power Input.......................................................................................................................3-4

Table 3-5. Connector P6 - Auxiliary I/O..................................................................................................................... 3-5

Table 3-6. Connector P7 - RS232C .............................................................................................................................3-5

Table 4-1. Response Time........................................................................................................................................... 4-2

Table 4-2. Setpoints...................................................................................................................................................4-12

Table 4-3. Preamplifier Interface Board 977-210-10 Switch Settings.......................................................................4-15

Table 4-4. Jumper Positions for Preamplifier Interface Board 977-210-10...............................................................4-15

Table 4-5. Jumper Positions for Preamplifier Electrometer Board 977-200-15 ........................................................4-15

Table 4-6. Model 946A-200 Option Jumpers............................................................................................................ 4-16

Table 4-7. UDR Function Switch Positions/Function ............................................................................................... 4-17

Table 4-8. Model 946A-200 Error Codes.................................................................................................................. 4-17

Table 4-9. Preamplifier Register Addresses ..............................................................................................................4-19

Table 4-10. Electrometer Control Bit Assignments.....................................................................................................4-20

Table 4-11. Output Signals (U14) ...............................................................................................................................4-29

Table 4-12. U1 Outputs............................................................................................................................................... 4-30

Table 4-13. Write Register Functions.......................................................................................................................... 4-31

Table 4-14. Counter Control Register Write Functions............................................................................................... 4-31

Table 4-15. Relay Control Register Write Functions..................................................................................................4-32

Table 4-16. Bargraph Write Address........................................................................................................................... 4-32

Table 4-17. Status Indicator Write Functions.............................................................................................................. 4-33

Table 4-18. Hex Data (Written to Address 4008).................................................................................

Table 4-19. Control Signal Address Decoding (U34)..................................................................................................4-35

Table 4-20. Data Entry Read Functions ...................................................................................................................... 4-36

Table 4-21. Function Switch Logic.............................................................................................................................4-36

Table 4-22. Sensitivity Select Read Functions............................................................................................................ 4-37

Table 4-23. Switch Input Bit Assignments (U62) ....................................................................................................... 4-37

Table 6-1. Electronic Adjustments ..............................................................................................................................6-1

.......................4-34

viii

Section 1 - Introduction

General Description

The Victoreen Model 945A is a wide-range area monitoring system with a detectable range of 10-1 to 107
mR/h. The system is comprised of the Model 977-210 Ion Chamber Detector, with local preamplifier, and
a Model 946A-200 Universal Digital Ratemeter (UDR). The detector and preamplifier are connected by
two five foot cables, encased in a flexible conduit. Other cable lengths, of up to 100 feet between
preamplifier and detector, are available. Both the detector and preamplifier are wall mounted in an area
designated by the customer. The 946A-200 Universal Digital Ratemeter is mounted in a rack in the
control room. A more detailed description of each piece of equipment can be found in the following
paragraphs.

Ion Chamber Detector/Preamplifier, Model 977-210
Ion chamber detectors are similar to capacitors, with two electrodes separated by a volume of air. In

order to operate, an electrical potential is applied between the electrodes. Thus, one electrode will have
a positive charge and the other a negative charge (relative to each other). Incident ionizing radiation will
cause the air in the volume between the electrodes to dissociate into positive and negative ions. Each
ion will be attracted to the electrode of opposite polarity. Ions that reach the electrode result in charge
transfer. The charge transfer causes a current to flow in the connecting wiring, representing the
measured amount of radiation intensity experienced by the ion chamber.

The Model 977-210 Wide-Range Ion Chamber Detector is a gamma sensitive radiation detection device,
which measures radiation in the range of 1 x 10-1 mR/h to 1 x 107 mR/h with an energy dependence of

less than ± 10% from 60 keV to 3 MeV. The pre-amp is housed in a gasket sealed enclosure.
Interconnection between the detector and pre-amplifier is accomplished via two five foot cables, encased
in a flexible conduit.

The wide range ion chamber detector design includes a single ion chamber with a volume of
approximately 1000 cc. The chamber walls are made of tissue equivalent plastic. An outer wall, made of
aluminum, is provided to protect the ion chamber and to mechanically interface with Victoreen’s Model
848-8 Field Test Source. The ion chamber is biased at a nominal 500 volts and produces an output

current proportional to radiation absorbed in the chamber. The current is approximately 8 x 10
The ion chamber assembly makes use of a double seal design, where the actual ion chamber is back

filled with nitrogen at atmospheric pressure. The connector area is sealed against moisture and
particulate through the use of a sealed, liquid tight flexible conduit between the detector and preamplifier
electronics.

The preamplifier contains a microprocessor controlled, auto-zeroing, integrating electrometer, a
programmable gain amplifier, an analog - to - digital converter, an asynchronous serial communications
interface, an electronic check source, and the detector high voltage power supply. Communications with
the UDR is accomplished via the optically isolated Victoreen Serial Communication Loop driver/receiver
circuitry.

-11

A/R/h.

1-1

Specifications, Ion Chamber Detector

Detector Type
Detector Volume
Detector Constant

Detector Capacitance
Inner Chamber Gas
Radiation Detected
Detectable Range

Energy Dependence
Accuracy
Power Requirement

Check Source
Dimensions (H x W x D)

Housing
Weight

Operating Temperature
Storage Temperature
Relative Humidity

Max. External Pressure

Ionization chamber
Approximately 1000 cc

Approximately 8 x 10
30 Picofarads nominal
Dry nitrogen @ atmospheric pressure
Gamma and X-Ray

1 x 10-1 to 1 x 107 mR/h
± 10% from 60 keV to 3 MeV (Refer to Figure 1-1)
± 15% of true dose for Cs-137
Approximately 500 VDC; high voltage level verified
through auto-check routine
Electronic check source actuated from UDR front panel

10.31 in. x 10.5 in. x 10.5 in.
(26.19 cm x 26.67 cm x 26.67 cm)
Outer chamber protective cover is aluminum. Inner
chambers are conductive, tissue equivalent, plastic
11 lb. (5 kg)

0o to 130o F (-16o to 54o C)
0o to 132o F (-16o to 56o C)

0 to 95% non-condensing
15 psig

Specifications, Preamplifier, Model 977-210-95

Housing
Interface to detector

Interface to Readout

Interface Cable Requirement

Power Requirement
Auxiliary Alarm Output

Auxiliary Analog Output
Dimensions (H x W x L)

Weight
Operating Temperature

Storage Temperature
Relative Humidity

Electronics Life Expectancy

Steel, NEMA 4 type
Approximately 5 feet of signal cable and high voltage

cable contained within a flexible conduit. (Other lengths
available).
Victoreen Comm Loop interface to 942A UDR through
Model 942-200-80 Communications Board. Capable of
driving up to 3000 feet of cable at 4800 Baud.
Seven (7) conductors, 16 AWG for maximum
preamplifier/readout distance, excluding local alarm
requirements
+15 Vdc @ 250 mA

-15 Vdc @ 50 mA

- 12 Vdc @ 150 mA (maximum)
0 - 10 Vdc, 2 k? min.

11.5 in. x 8.94 in. x 4.20 in.
(29.21 cm x 22.71 cm x 10.67 cm)
12 lb. (5.4 kg)

0o to 130o F (-16o to 54o C)
0o to 132o F (-16o to 56o C)

0 to 95% non-condensing
Approximately 104 rads

-11

A/R/h

1-2

30

20

10

CALCULATED VALUEACTUAL VALUE

0

-10

-20

-30

-40
2 3 4 5 6 8

0.01 0.1 1.0 10

Energy in MeV

2 3 4 5 6 82 3 4 5 6 8

Figure 1-1. Detector Energy Response

1-3

Universal Digital Ratemeter, Model 946A-200
The Victoreen Model 946A-200 Universal Digital Ratemeter (UDR), when connected to a Model 977-210

Ion Chamber Detector, comprises a monitoring system which operates in the range of 10-1 to 107 mR/h.
The UDR provides display, control, and annunciation functions for the monitoring system. Refer to Figure
1-2 for view of the 946A-200 front panel.

Standard features for the instrument consist of a three digit display of the radiation value and a multi­colored bargraph indicator which covers the entire range of the detector. The bargraph will change color
in the event of an alarm condition. Front panel alarm indicators and rear panel output relays for alarm
annunciation are also included. Front panel pushbuttons are provided to apply power, display alarm limit
set points, for alarm acknowledgment, and the activation of a check source function.

Analog outputs of 0 to 10 VDC and 4 to 20 mA (2) are provided for recording and computer monitoring.
The 0 to 10 VDC output may also be used to drive a remote meter or a local (i.e. near the detector)
indicator.

All electronics required to interface to the VICTOREEN 977-210 series detector/preamplifier are included
within the 946A-200 UDR. These electronics consist of a low voltage power supply, and the
hardware/software required for UDR operation. The system also includes a positive overrange indication

on the display when radiation intensity exceeds the full scale value of 10

7

mR/h.

The following paragraphs describe the available options. A separate manual, for each option board, is
available with more detailed information. Listed below are the option boards currently available.

1. 942-200-75: ANALOG OPTION INPUT BOARD - (Generally not used for normal operation with the 946A-200
UDR, however, it is used if the UDR is part of a simulator) Contains four separate channels for analog input. A 0
to 10 VDC input or 4 to 20 mA input can be selected independently for each channel using the jumpers and
switches provided on the board. Possible inputs to the board include: temperature, pressure, flow, or simulated
radiation.

2. 942-200-80: COMMUNICATIONS LOOP OPTION BOARD - Designed to enable a EIA RS232C serial
communications link between VICTOREEN's ratemeter and a user computer system or CRT terminal, with baud
rates ranging from 50 baud to 19200 baud. An asynchronous communication interface adapter is utilized to
format the data and control the interface.

The Communication Loop Option Board also provides an isolated multi-drop, serial communications port for

interface with a supervisory computer system. The serial data is in a modified RS232 format, and utilizes
Victoreen’s proprietary VICO loop protocol. For maximum electrical noise protection, a six conductor
communication cable is used.

The 946A-200 UDR has one standard 942-200-80 Communications Board to support communications between

the preamplifier and the 977-210 Detector/Preamplifier.

3. 942-200-95: ANALOG OUTPUT BOARD - Designed to provide a user selectable single output voltage of: 0 - 10
Vdc, 0 - 5 Vdc, 0 - 1 Vdc, 0 - 500 mVdc, 0 - 100 mVdc, 0 - 50 mVdc, or 0 - 10 mVdc.

4. 942-200-95M1: DUAL ANALOG OUTPUT BOARD - Designed to provide two user selectable output voltages.
Output #1 is either 0 - 5 Vdc, or 0 - 10 Vdc, while output #2 is either 0 - 10 mV dc, 0 - 50 mVdc, 0 - 100 mVdc, 0 ­500 mVdc, or 0 - 1 Vdc.

1-4

Application
The Model 946A-200 UDR may be used with all VICTOREEN 977 series Ion Chamber Detectors. The

detector/preamplifier, when connected to the UDR, will comprise a single channel digital area monitoring
system. For additional information on various applications, please contact VICTOREEN, Inc.,
Applications Engineering Group.

Specifications

General specifications for the 946A-200 UDR are listed below. The 946A-200 is rated for nuclear
applications, and

any repairs to it by personnel not qualified to ANSI 45.2.6, 1978, Skill Level II will void

the nuclear rating.

Main Display
Bargraph Display

(Dynamic Range)
Alarm Indicators

Alarm Delay
Display Selection

(Momentary Pushbuttons)

Check Source
Alarm Ack.

Power ON/OFF
Relay Outputs

(Failsafe operation)

Analog Outputs
Alarm Ack Input

UDR Electronic Accuracy
Dimensions

(H x W x D)
Weight
Power
Operating Temperature

Relative Humidity
Compatible Detector

Three digits with backlighted radiation units display and floating
decimal point. Three digits plus exponent for data entry/display

Three segments per decade, 10-1 to 107 mR/h (24 segments), tri­color, indicating channel status.
HIGH Alarm (Red LED) - Flashing until acknowledged
WARN Alarm (Amber LED) - Flashing until acknowledged
FAIL Alarm (Red LED) - Does not flash, is not manually acknowledged
RANGE Alarm (Red LED), overrange/underrange - Does not flash,
automatically acknowledges
3 minute alarm mute on channel power-up

HIGH, High Alarm limit
WARN, Warn Alarm limit
Activates electronic Check Source and associated green LED
indicator. “Latching pushbutton operation”
Alarm acknowledgment: causes alarm indicators to go to a steady on
state after acknowledgment, relays will reset when radiation level
drops below setpoint. Internal jumper causes alarms to be reset
automatically when radiation level drops below set point (no operator
input required).
Alternate action push-button for AC power to the unit

HIGH Alarm - 1 set. DPDT rated 5 A @ 120 Vac (one set 120 Vac
powered for use with optional local alarm)
WARN Alarm - 2 sets. DPDT rated 5 A @ 120 Vac
FAIL Alarm - 2 sets. DPDT rated 5 A @ 120 Vac
DC contact rating for all relays is 5 A @ 29 VDC
4 to 20 mA (2) and 0 to 10 Vdc, logarithmic and may be scaled for any
one decade (minimum) to the full range of the unit (maximum)

Optically isolated DC input
± 1% digit (± 1% of the displayed value), exclusive of the detector

energy response

3.5 in. x 5.6 in. x 13.5 in.
(8.9 cm x 14.2 cm x 34.3 cm)

Approximately 3.7 lb. (1.67 kg)
120 Vac ±10%, 50/60 Hz, 28 watts (240 Vac optional)

32° F to 122° F ( 0° C to + 50° C )
0 to 95% non-condensing
977 Series, Ion Chamber

1-5

Auxiliary Equipment

Support/Test Equipment Model 848-8: Field Calibrator
Model 942TS: UDR Test Set
Model 948-1: Rack Chassis
Model 948A-4: Remote Alarm
Model 948-3: Table Top

Enclosure
Model 948-10: Panel Adapter
Model 50-150: Cable
Remote Indicator Model 948A-4: Remote Alarm
Model 948A-5: Remote

Alarm/Meter

kR/h

00.NNN

mR/h
R/h

CHECK
SOURCE

HIGH WARN

ON

1.1

OFF

Figure 1-2. Front Panel, Model 946A-200 Universal Digital Ratemeter

10 10 10 10 10 10 10

23 45 67

ALARMS

HIGH WARN FAIL RANGE

ALARM
ACK.

mR/h

MODEL 946A

VICTOREEN

1-6

(BLANK PAGE)

1-7

Section 2 - Receiving Inspection and Storage

Receiving Inspection

Upon receipt of the unit:

1. Inspect the carton(s) and contents for damage. If damage is evident, file a claim with the carrier and
notify the Victoreen Customer Service Department.

Fluke Biomedical RMS

6045 Cochran Rd.

Cleveland. Ohio 44139

Phone: [phone]

Fax: [phone]

2. Remove the contents from the packing material.

3. Verify that all items listed on the packing list have been received and are in good condition.

NOTE
If any of the listed items are missing or damaged, notify the Fluke
Biomedical RMS Customer Service Department.

Storage

Storage of Fluke Biomedical RMS instruments must comply with Level B storage requirements as
outlined in ANSI N45.2.2 (1972) Section 6.1.2(.2). The storage area shall comply with ANSI N45.2.2
(1972) Section 6.2 Storage Area, Paragraphs 6.2.1 through 6.2.5. Housekeeping shall conform to ANSI
N45.2.3 (1972).

Level B components shall be stored within a fire resistant, tear resistant, weather tight enclosure, in a well
ventilated building or equivalent.

Storage of Fluke Biomedical RMS instruments must comply with the following:

1. Inspection and examination of items in storage must be in accordance with ANSI N45.2.2 (1972)
Section 6.4.1.

2. Requirements for proper storage must be documented and written procedures or instructions
must be established.

3. In the event of fire, post-fire evaluation must be in accordance with ANSI N45.2.2 (1972),Section

6.4.3.

4. Removal of items from storage must be in accordance with ANSI N45.2.2 (1972), Sections 6.5
and 6.6.

2-1

(BLANK PAGE)

2-2

Installation

Section 3 - Installation

Installation consists of mounting the equipment, making the required electrical connections, and entering
the desired set points. Installation drawings are provided in Appendix B of this manual.

CAUTION

Remove all power prior to installing the UDR.

Detector Mounting

Refer to Engineering Drawing GEL 977-210, provided in Appendix B, for detector and preamplifier
mounting dimensions, weights and recommended fasteners.

UDR Mounting

The UDR is a self contained unit which can be mounted in four different ways.

CAUTION

When installing the UDR in enclosed panels or cabinets, ensure that the maximum
operating temperature (122° F) is not exceeded. The total heat load should be

calculated to determine whether cooling by natural convection or forced
ventilation (i.e. fans) is required. The heat load for a single UDR is approximately
96 BTU/hr.

When more than four units are to be mounted in a cabinet, it is recommended that
the center position in each chassis be left blank to facilitate the flow of cooling air
through the cabinet.

NOTE
For seismic applications, the rear of the chassis must be supported, or the sides of
the chassis must be fastened together. For further information, contact Fluke
Biomedical RMS.

1. The first mounting utilizes a 19 inch rack chassis adapter, Victoreen Model 948-1. This configuration
requires 3.5 inches of rack height and can be used to mount up to three UDRs side by side. A blank
filler panel, Victoreen Model 948-2, is available to cover unused mounting positions. In multiple UDR
installations, the center mounting bay should be fitted with a Model 948-2 blank panel to facilitate
cooling air flow.

2. The second mounting consists of a single channel table top enclosure, Victoreen Model 948-3.
Dimensions for the enclosure are 4.5 inches high by 6.8 inches wide by 14.9 inches deep. This
enclosure is used primarily in a laboratory environment. Refer to drawing 948-3-5 for mounting
dimensions.

3. The third mounting consists of a panel mount enclosure, Victoreen Model 948-9. Cutout dimensions
for this enclosure are 3.75 inches high by 6.45 inches wide, the outside dimensions for the enclosure
are 4.0 inches high by 6.7 inches wide by 13.7 inches deep. This mounting must also be rear
supported in seismic applications. Refer to drawing 948-9-5 for mounting dimensions.

3-1

4. The fourth mounting utilizes the Victoreen Model 948-10 Rack Chassis Adapter to mount a 946A-200
UDR into an existing Victoreen analog meter rack chassis, such as those used for the Victoreen 842
series of analog ratemeter.

The UDR is simply inserted into the selected mounting enclosure and secured using the front panel pawl
fastener.

WARNING

Ensure all power is off prior to connecting the field wiring.

Electrical Interface

Electrical connections at the preamplifier are made via the mating “MS” style connector supplied with the
detector. It is not necessary to open the preamplifier enclosure to complete the interconnection to the
ratemeter. The desiccant bags inside the preamplifier enclosure should be checked for moisture
absorbtion prior to placing into service. Each bag contains a color indicator that indicates when it should
be replaced.

NOTE
The electrometer circuitry in the preamplifier is highly sensitive to moisture and
physical damage. Use extreme care when the preamplifier case is opened as the
high impedance electrometer circuitry is easily damaged. Do not leave the
preamplifier enclosure in the open position for any extended period of time.

Electrical interconnections at the Model 946A-200 Readout are performed using the mating connector kit,
VICTOREEN part number 946A-100-4 (supplied with the Readout), by using the connector Input/Output
assignments provided in Tables 3-1 through 3-6, and the drawings provided in Appendix B. Refer to
drawing 945A-3, showing complete channel loop wiring, including remote alarms (if used)

Connector pins should be soldered to customer furnished cable, using 60/40 tin/lead resin core solder
with a soldering iron of 50 watts or less to avoid connector damage.

Table 3-1. Rear Panel Connections

Connector Contact Function

P1 Relay, Remote Alarm

Acknowledge

P2 Detector Connector, VICO

Loop Communications,

Remote Alarm Output
P3 AC Power Input
P6 Analog Outputs (4 - 20 mA, 0 -

10V)
P7 RS232C Communications

3-2

Table 3-2. Connector P1 - Input/Output

Pin Signal Internal Connection

1 Spare Not Used
2 Spare Not Used
3 Spare Not Used
4 Spare Not Used
5 Spare Not Used
6 Spare Not Used
7 Fail Relay, common Relay Board K3-A
8 Fail Relay, n.o. Relay Board K3-B

9 Fail Relay, n.c. Relay Board K3-C
10 Fail Relay, common Relay Board K3-D
11 Fail Relay, n.o. Relay Board K3-F
12 Fail Relay, n.c. Relay Board K3-E
13 Warn Relay, common Relay Board K4-A
14 Warn Relay, n.o. Relay Board K4-B
15 Warn Relay, n.c. Relay Board K4-C
16 Warn Relay, common Relay Board K4-D
17 Warn Relay, n.o. Relay Board K4-F
18 Warn Relay, n.c. Relay Board K4-E
19 Alarm Relay, common Relay Board K5-A
20 Alarm Relay, n.o. Relay Board K5-B
21 Alarm Relay, n.c. Relay Board K5-C
22 Spare Not Used
23 Spare Not Used
24 Spare Not Used
25 + Remote Acknowledge Main Circuit Board J9-1
26 - Remote Acknowledge Main Circuit Board J9-2
27 Spare Not Used
28 Spare Not Used
29 Spare Not Used
30 Spare Not Used
31 Spare Not Used
32 Spare Not Used
33 Spare Not Used
34 Spare Not Used
35 Spare Not Used
36 Spare Not Used
37 Spare Not Used

n.o. = normally open
n.c. = normally closed

Relay contacts listed are in the shelf or de-energized state. Relays are operated in the fail-safe mode,
de-energizing to indicate a tripped condition.

3-3

Table 3-3. Connector P2 - Detector Connector

Pin Signal Internal Connection

1 +15 VDC Not used in most applications

2 -15 VDC Not used in most applications

3 Supply Ground Power Supply Ground

4 Transmit + Communication Board

5 Transmit - Communication Board

6 Receive + Communication Board

7 Receive - Communication Board

8 Loop Voltage +

Communication Board

Fused + 15 VDC

9 Loop Voltage -

Communication Board

Fused -15 VDC
10 0 - 10 Vdc* Main Circuit Board J5-10
11 Ground Main Circuit Board J5-9
12 Check Source Line Not used in most applications
13 Neutral Not used in most applications
14 Alarm Switched Line Not used in most applications

* 0 - 10 Vdc selected for customer use on P2 (10,11) or P6 (5, 6), not both.

Table 3-4. Connector P3 - Power Input

Pin Signal Internal Connection

1 120 Vac, Line Line fuse (F2)
2 120 Vac, Neutral Power Supply, 120 Vac (n)
3 Safety Ground Chassis

3-4

Table 3-5. Connector P6 - Auxiliary I/O

Pin Signal

1 4 - 20 mA Output # 1
2 Ground
3 4 - 20 mA Output # 2
4 Ground
5 0 - 10 V *
6 Ground
7 Analog Output Option

8 Ground
17 Not Used
18 Not Used
19 Not Used
20 Not Used
21 Not Used
22 Not Used
23 Not Used
24 Not Used

* 0 - 10 Vdc selected for customer use on P2 (10,11) or P6 (5, 6), not both.

Table 3-6. Connector P7 - RS232C

Pin Signal

1 Protective Ground

2 Transmit Data

3 Receive Data

4 Request to Send (RTS)

5 Clear to Send (CTS)

6 Data Set Ready (DSR)

7 Signal Ground

8 Receive Line Signal Detect
20 Data Terminal Ready

3-5

Set-up

To place the UDR in operation, the following steps should be performed:

NOTE

Ensure you have read and fully understand section 4, prior to continuing.

1. Verify jumpers and DIP switches on the preamplifier and ratemeter are set for the operational
features desired. Refer to Section 4 Tables 4-3 through 4-6 for additional information.

2. Apply power to the unit.

3. Enter detector dependent set points such as analog output, High/Low scale Value, and calibration
constant, using the procedure outlined in Section 4, and Tables 4-2 & 4-7.

4. Enter channel dependent setpoints such as Alarm Limits are to be entered using the procedure
described in Section 4, and Tables 4-2 & 4-7.

5. Electronic adjustments affecting calibration are factory set and should not be readjusted for initial
operation unless the UDR has been in storage for more than one year. If the Unit has been in
storage for more than one year, the electronic calibration described in Chapter 6 should be
performed.

3-6

Section 4 - Operation/Functional Description

Operation

This section describes the operation and set up of an area monitoring system consisting of a Model
946A-200 UDR and a Model 977-210 Detector/Preamplifier interconnected via a serial communications
interface. The detector preamplifier provides the electronics interface between the detector and the UDR.
It consists of a high voltage/communications interface printed circuit board and an electrometer printed
circuit board. The preamplifier measures the current output of the ion chamber, generates the high
voltage supply for the detector, performs periodic diagnostic checks, and performs an electronic check
source function on demand from the UDR. The current measurement is converted to a dose rate and
this, along with the operational status of the preamplifier and detector, are transmitted to the UDR.

The 946A-200 UDR uses this information to generate the dose rate display, error codes, alarms, and
analog outputs.

Operation of the 946A-200 UDR consists of operator functions and configuration functions. All operator
functions are performed using the front panel shown in Figure 4-1. Configuration functions are performed
using internal switches and/or jumpers, which are accessible with a partial removal of the UDR from the
mounting enclosure (refer to Table 4-6). Calibration involving trimpots are described in Section 6.

Detector Operation
The Model 977-210 wide range ion chamber detector is an eight decade, linear reading radiation monitor.

The chamber, cables, and preamplifier are sensitive to moisture; therefore, the detector and preamplifier
are sealed. The preamplifier box contains a desiccant package to remove moisture from the interior of
the preamplifier. The desiccant has a color indicator to show when it should be replaced.

The detector electrometer converts the current from the ion chamber to a voltage which is measured by
the analog to digital converter of the preamplifier. Under program control, this measurement is made
every 50 milliseconds on the first five decades and every 100 milliseconds on the upper three decades.

The electrometer is auto-ranging and auto-zeroing. An internal coarse zero control (factory adjusted) is
provided. The microprocessor in the preamplifier performs data collection, averaging, multiplication by a
stored calibration factor, range changing, high voltage check, detector cable integrity check, and
communication with the 946A-200 UDR.

The high voltage check and integrity check are run, under program control, every 256 seconds. The high
voltage check is a measurement of the high voltage to ensure that the value is sufficient for 100%
collection at full scale.

4-1

The detector cable integrity check is a pulse that is injected on the detector high voltage. The chamber
capacitance couples the pulse into the electrometer where it is seen as a high current. If either the high
voltage lead or signal lead are not connected to the chamber, the pulse does not appear on the
electrometer. The measurement cycle is interrupted for approximately one (1) second whenever the
integrity check is performed. The integrity check and high voltage check are not performed when the
instrument is reading on the three highest decades. A reading in these ranges serves as an indication of
the functioning of the instrument. The Maintenance mode operation also inhibits these checks from being
made.

There is a hysteresis built into the range changing function of the electrometer. The range change-up
occurs at the decade points whereas the range change-down occurs at 80% of the decade points. This
hysteresis results in the display of only two significant digits when in the upper 20% of a decade.
Whether or not this occurs depends on which direction the radiation level is trending. An increasing trend
will result in three significant digits while a decreasing trend will result in two significant digits.

The response times for a change in reading within the same decade are listed in Table 4-1. If a change
of 100 to 1000 times the current reading occurs, the instrument will range change within a single 50
millisecond clock cycle.

Table 4-1. Response Time

DECADE RANGE RESPONSE TIME

1 0.1 to 1.0 mR/h 80 sec.
2 1.0 to 10 mR/h 32 sec.
3 10 to 100 mR/h 16 sec.
4 100 to 1000 mR/h 4 sec.
5 1.0 to 10 R/h 2 sec.
6 10 to 100 R/h 0.9 sec.
7 100 to 1000 R/h 0.2 sec.
8 1.0 k to 10 kR/h 0.2 sec.

A manual electronic check source may also be initiated from the UDR by the operator to check detector
operation. Upon removing the check source request, the UDR again displays the detector output

CAUTION

Do not actuate the check source when the reading is above 1 R/h.
The radiation measurement is additive to the check source signal
resulting in improper values from the check source. This may
result in the UDR indicating a failure when the instrument is
operating correctly.

The detector preamplifier contains a High Voltage/Communications Interface Board containing an RS232
driver, a Victoreen Communications Interface Driver, the detector high voltage power supply, a local 0 ­10 Vdc analog output, and a -12 Vdc open collector alarm output.

4-2

Operation / Functions

Operation of the 946A-200 UDR consists of operator functions and configuration functions. All operator
functions are performed using the front panel. Configuration functions are performed using internal
switches and/or jumpers which are accessible with a partial removal of the UDR from the mounting
enclosure.

Normal Operation

If the measured radiation field is within the range of the detector during power-up, the mR/h, R/h, or kR/h
value will be displayed as a three digit number with a floating decimal point (i.e. .XXX mR/h). The
bargraph will display the value of radiation, with a resolution of three segments per decade, over the
range of the detector or eight decades. The bargraph should be green, providing the operator with a
visual indication of normal operation. All other indicator LEDs should be off. In very low background
environments (< 0.1 mR/h), the range indicator LED may be illuminated.

WARN/HIGH Alarms

If the measured radiation field increases above the WARN alarm limit, the WARN alarm indicator will turn
on flashing (amber color), the bargraph will change color to amber, and the warn alarm relay will de­activate. If the measured radiation field increases above the HIGH alarm limit, the HIGH alarm indicator
will turn on flashing (red color), the bargraph will change color to red, and the high alarm relay will de­activate.

NOTE

Non-failsafe relay operation for the HIGH and WARN alarms is available as an option at time of purchase.

The UDR can be configured to automatically reset the alarm relays and alarm indicators by removing
JP3-3, or it can hold the alarm relays energized and flash the alarm indicators until the alarm
acknowledge (ALARM ACK) push-button is pressed. If the ALARM ACK push-button is pressed while the
alarm condition still exists, the indicators will go to a steady state, and the relays will remain energized
until the alarm condition returns to normal. Upon resumption of normal operation, the relays and alarm
indicators will de-energize. The bargraph color will always indicate the current status; green for normal,
amber for warn, and red for a high alarm.

Front panel pushbuttons labeled HIGH and WARN can be used to display the respective alarm set points.

Range Alarm

If the measured radiation field is below the Underrange setpoint, the front panel display will indicate 0.00
mR/h, and the RANGE alarm indicator will illuminate in red, the bargraph will indicate the actual radiation
value, and the analog output will be set to zero. The minimum range is an adjustable setpoint and is
defaulted to 1.00-1 mR/h. When the measured radiation field increases into the range of the detector, the
RANGE alarm indicator will extinguish and normal operation will continue.

If the measured radiation field goes above the overrange set point, the RANGE alarm indicator will
illuminate and the front panel display will indicate EEEEE, the bargraph will illuminated in RED, and the
analog output will be set to full scale. The maximum range of the detector is used is determine by the
overrange set point. When the measured radiation field returns within the maximum operating range of
the detector and the condition is acknowledged, the RANGE alarm indicator will extinguish and normal
operation will resume.

4-3

Fail Alarm

Detector failure, communication loss, or UDR microprocessor failure are some of the conditions which
can produce a FAIL alarm and in some cases an error display. The fail condition is true whenever an
equipment failure is detected and false when no equipment failures are detected. When a fail condition
occurs, other than power failure, the red FAIL alarm indicator illuminates and the fail relay coil de­energizes.

A FAIL alarm will clear automatically when the failure conditions are no longer present.

Check Source

The check source push-button and electronics are provided to verify detector operation. To operate the
check source, press the CHECK SOURCE push-button and hold it down for one second. The electronic
check source circuit will energize, the check source indicator will illuminate (green), and the check source
radiation value will be displayed on the front panel. Pressing the CHECK SOURCE push-button again will
cause the UDR to return to normal operation. Removing JP3-5 allows alarms to be activated if alarm
limits are exceeded by the check source radiation value. Installing JP3-5 allows alarms to be muted if
alarm limits are exceeded by the check source radiation value.

The analog outputs are set to zero during check source operation.
A built-in timer will turn the Check Source OFF after 10 minutes.
Firmware Version
Both detectors and UDR require a programmed PROM for operation. For the part number and the latest

revision of these PROMs, see the detector Calibration Data Sheet and/or Factory Test Data Sheet.

4-4