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RAM 100
Surface Contamination Meter
Operating Manual
DPM / CPM
Version 3.0 - November 2000
Document # PRIR75R0.DOC
R TEM INDUSTRIES LTD. ROTEM Industrial Park, 5000 Highlands Parkway,
P.O.Box 9046, Beer-Sheva 84190, ISRAEL Suite 150 Smyrna, Georgia 30082, USA
Tel: 972-8-6571312/6568652 Tel: (770) 432-2744,
Fax: 972-8-6555984/6568005 Fax: (770) 432-9179
E-Mail: sales@rotemi.co.il
Web Site: http://www.rotemi.co.il
RAM 100 / Operating Manual Page 2
Version / Revision Log: RAM 100 / Operating Manual
Ver./Rev.# Date Revised Pages Comments
2ed
edition July 1993 DPM version, Doc. # BM9304.WP
CPM version, Doc. # BM9307.WP
3.0 November 2000 1-3 Doc. # PRIR75R0.DOC
DPM + CPM updated WORD version
Updated ROTEM address, table of contents,
addition of this log, letter size pages
13 Err. value corrected
WARNING:
For air delivery, the detector should be placed in a sealed container to ensure gradual changes
in pressure, which otherwise may cause irreparable damage to the GM tube.
ROTEM Industries Ltd. reserves the right to change specifications without advance notice.
Ref. PRIR75R0.DOC
RAM 100 / Operating Manual Page 3
Table of Contents
1. The RAM 100 ............................................................................................................................... 4
1.1. General Description.................................................................................................................. 4
1.2. Ordering Information................................................................................................................ 5
2. Specifications................................................................................................................................ 6
3. Operating Instructions ................................................................................................................ 8
3.1. Preparation for Use................................................................................................................... 8
3.2. Starting-up ................................................................................................................................ 8
3.3. General Functions..................................................................................................................... 8
3.4. Special Functions...................................................................................................................... 8
3.5. Alarms .................................................................................................................................... 11
3.6. Push-buttons Function ............................................................................................................ 12
3.7. Battery Replacement............................................................................................................... 12
4. Calibration ................................................................................................................................. 13
4.1. General Description................................................................................................................ 13
4.2. Calibration Procedure............................................................................................................. 13
4.3. Base Unit Fixed “Calibration”................................................................................................ 14
4.4. Pulser Adapter – Model A-0270............................................................................................. 15
RAM 100 / Operating Manual Page 4
1. The RAM 100
1.1. General Description
The RAM 100 radiation contamination meter is a state-of-the-art microprocessor-based
instrument, designed to detect very low levels of alpha, beta and gamma surface radiation
contamination. Two versions are available: RAM 100 DPM and RAM 100 CPM.
RAM 100 DPM version reads directly in disintegration units. The user should select the
efficiency factor. This value can be selected from the following values: 8, 9, 10, 11, 12,
13, 14, 15, 16, 17, 18 and 100 (%). When 100 (%) is selected the RAM 100 actually
displays the cpm value. After the efficiency factor is selected, the RAM 100 can be
calibrated to give the exact dpm reading that fits to a specific isotope.
The dpm calculation is:
cpm x 100
EFF.
When: EFF. = Efficiency factor
In RAM 100 CPM version, the efficiency factor value equals 100 and it cannot be
changed by the user.
The RAM 100 meter is built of two parts:
a. detector, amplifier and HV assembly.
b. base unit including rate-meter and display.
The RAM 100 detached detector is a GM
pancake tube of 1.75" effective diameter,
with a thin mica window covered by a
protective copper beryllium screen. The
detachable detector offers extra flexibility
for getting at underneath surfaces and
hard-to-reach places.
The meter is a one-hand-operation
instrument, portable, lightweight and
compact. Only three push-buttons are
needed for operation: ON/OFF, RESET/
MODE and SPEAKER/→→→→.
Three ways of indications enable the RAM 100 user to monitor and survey surface
contamination rapidly and accurately: a large four 7-segment LCD, an audible click
whose rate varies directly with count rate, and a LED indicator RESPONSE that flashes
with each incident radiation pulse.
RAM 100 / Operating Manual Page 5
The sophisticated software offers special features and optimal performance. A wide
dynamic range of up to 999,000 disintegration per minute, is obtained by the automatic
dead time correction, according to the preset calibration. A special averaging function
“smoothes” the readout and maintains fast response time, while keeping the standard
deviation at a minimum.
An automatic self-diagnostic procedure continuously checks both counter and detector,
and reports any case of detector failure. The meter also alarms in any case of reading
exceeding threshold value, reading overflow or low battery. Threshold can be selected
from a range of 9 preset threshold values. When the meter is turned off, the last threshold
value is kept in memory.
The RAM 100 meter can be placed in a holder. The detector surface is covered with a cap
for protection against mechanical damage.
1.2. Ordering Information
Item description Model No.
RAM 100 (incl. counter, detector, holder, cover cap, tel. connector) <dpm> RTM 9025
RAM 100 (same as RTM 9025 with threaded head) <dpm> RTM 9022
RAM 100 (incl. counter, detector, holder, cover cap, tel. connector) <cpm> RTM 9009
RAM 100 (same as RTM 9009 with threaded head) <cpm> RTM9024
RAM 100 detector (GM-10) with telephone connector 3-0020-01
RAM 100 detector (GM-10) with threaded head 3-0020-05
RAM 100 detector (GM-10) threaded head with telephone connector 3-0020-06
RAM 100 holder A-0110
Detector tester A-0070
Telephone cable A-0120
Belt hanger A-0130
Pancake hexagonal protective screen A-0141
Pulser adapter A-0270
RAM 100 / Operating Manual Page 6
2. Specifications
Display LCD readout showing:
- four digits for accurate and easy readout
- detector failure
- low battery
- overflow
- threshold
LED Count rate indication
Audio Internally mounted piezo-electric element
Measuring unit dpm - disintegration per minute
cpm - counts per minute
Controls - ON/OFF push-button
- RESET/MODE push-button for accurate measurement of
low level contamination and mode selection
- SPEAKER/→→→→ push-button to control audible indicator
volume and threshold and efficiency values
Power source One 9-Volt cell battery
- 50 hours minimum continuous operation, using an alkaline
battery (speaker off)
- Automatic battery check under full load
Detector Pancake GM tube (LND 73118 or equivalent)
Effective diameter 1.75”
Window thickness Mica, 1.5 to 2 mg/cm² protected by a copper beryllium screen
Background reading Approx. 500 dpm when 10% efficiency factor is selected
Sensitivity (137
Cs) Approx. 35000 dpm/mR/h when 10% efficiency factor is
selected
Count rate range 0 to 999,000 dpm
Accuracy ±15% of reading
Temperature range Operation: -10°C to +50°C (15°F to 122°F)
Storage: -20°C to + 60°C (-5°F to 140°F)
Humidity range 40% to 95% RH (non condensing)
RAM 100 / Operating Manual Page 7
Casing High impact plastic
Dimensions Counter Detector
Width: 6.7 cm (2.6") 7.1 cm (2.8")
Length: 11.0 cm (4.3") 27.0 cm (10.6")
Height: 4.6 cm (1.8") 8.9 cm (3.5")
Weight 780 g (1.7 lb)
Surface sensitivity (in contact), when efficiency value = 10%, using a hexagonal
cooper beryllium screen
Minimum
Detectable Level*
Isotope Energy
E or Emax
keV
Sensitivity
Kdpm/µµµµCi
Surface Sensitivity
__dpm__ __dpm__
pCi/cm² Bq/cm² pCi/cm² Bq/cm²
14C (β) 156 900 13 350 500 20 147
Pm (β) 224 4300 67 1800 108 3.8 99
Tc (β) 290 5150 76 2060 91 3.4 90
Sr+90
Y(β) 580+2280 14400 217 5880 16 0.6 36
Cl (β) 714 6850 98 2640 79 2.7 210
Pb (β) 1160 7950 120 3240 64 2.1
MDL - Minimum Detectable Level calculations are based on background reading of 500
dpm, and the confidence level is 99%.
Surface sensitivity (in contact) in cpm units when using a hexagonal cooper beryllium
screen
Minimum
Detectable Level*
Isotope Energy
E or Emax
keV
Sensitivity
Kcpm/µµµµCi
Surface Sensitivity
__cpm__ __cpm__
pCi/cm² Bq/cm² pCi/cm² Bq/cm²
14C (β) 156 93 1.3 34.8 50 2
147Pm (β) 224 432 6.7 180 10.8 0.38
99Tc (β) 290 516 7.6 206.4 9.1 0.34 90
Sr+90
Y(β) 580+2280 1446 21.7 588 1.57 0.06 36Cl (β) 714 686 9.8 264 7.9 0.27 210
Pb (β) 1160 796 12 324 6.42 0.21
* Minimum Detectable Level calculations are based on background reading of 50 cpm, and
the confidence level is 99%.
RAM 100 / Operating Manual Page 8
3. Operating Instructions
3.1. Preparation for Use
Remove the instrument from the shipping container and check for physical damage.
In case of damage, report it immediately to the carrier.
Do not attempt to install or operate damaged equipment since safety and performance
may be affected
3.2. Starting-up
Press the ON/OFF push-button. When the meter is turned on, it carries out a short self-
test procedure and the following sequence is displayed:
- all the segments + a short beep
- thr. LCDs
- last threshold value
- EFF. LCDs (only in DPM version)
- last efficiency value (only in DPM version)
After this sequence the actual reading is displayed and the meter is ready for use.
3.3. General Functions
a. Readout: The measuring units are disintegration per minute. Values through 9999
dpm are expressed in 1 to 4 digits. For higher values, up to 999,000 dpm, a factor of
1000 will be indicated by displaying E.
For example: 10,400 = 10.4E
127,000 = 127E
b. LED: The LED indicator RESPONSE located above the LCD, blinks with each
incident radiation pulse.
c. Reading reset: To reset the reading press the RESET push-button. The reset function
provides a rapid means of discharging the display reading and enables accurate
measurement of low level contamination.
d. Audible indication: When the meter is turned on, the audible indication is activated
at its high volume, so that the rate and trend of measurement are noticed. To decrease
speaker volume, press SPEAKER push-button once, to turn it off press once again. This
volume control effect is specially activated at low rates of measurement.
3.4. Special Functions
Definitions:
Short press - RESET push-button, press and release it before 2 seconds are elapsed.
Long press – MODE push-button, press and hold at least for 2 seconds.
RAM 100 / Operating Manual Page 9
Special Functions enable to carry out threshold setting, efficiency factor (dpm version) and
calibration (through a sequential procedure).
RAM 100 DPM Special Functions Block Diagram
RAM 100 CPM Special Functions Block Diagram
RAM 100 / Operating Manual Page 10
3.4.1. Threshold setting
The first press on the MODE push-button activates special functions. The thr. LCDs will
be displayed.
Advance to the chosen value by pressing the SPEAKER/→→→→ push-button. The following
threshold values may be selected:
2000, 2500, 3000, 3500, 4000, 10.0E, 50.0E, 100E, 200E, 999E.
Pressing the RESET push-button activates the calibration mode.
Pressing the MODE push-button returns to normal operation.
3.4.2. Efficiency factor setting – only in DPM version
When entering the efficiency factor setting, the EFF. LCDs will be displayed.
Advance to the chosen efficiency value by pressing the SPEAKER/→→→→ push-button.
The following efficiency values may be selected:
8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, and 100%.
Pressing the RESET push-button activates the efficiency factor.
Pressing the MODE push-button returns to normal operation.
3.4.3. Calibration mode (see chapter 4)
The CAL. LCDs will be displayed.
Press the SPEAKER/→→→→ push-button to perform the calibration procedure, according to
section 4.2. The actual reading will blink on the display. Press the RESET/MODE push-
button to go into normal operation.
Note: When the thr., EFF. or CAL. LCDs are displayed you don't have to enter these
modes, just press the MODE push-button instead of the SPEAKER/→→→→ push-button to
advance to the next function. To exit special functions mode, either complete the
sequence or press the RESET push-button. The selected values of the alarm threshold
and the efficiency factor are stored in a non-volatile memory, and are also retained after
the instrument is turned off.
The first value to be displayed when entering a special function is the last selected
value.
RAM 100 / Operating Manual Page 11
3.5. Alarms
a. Detector alarm: If the detector is defective or disconnected, the Err. LCDs blink on
the display
b. Battery alarm: If battery voltage decreases below 6.2V, the bAt. LCDs blink on the
display, and an interrupted audible alarm is activated.
To display the measured readings and mute the audible alarm, press the SPEAKER/→→→→
push-button. After the SPEAKER push-button is pressed, the bAt. LCDs will reappear
every 5 minutes for 2 seconds, and every 30 minutes accompanied by an audible beep to
remind of low battery condition.
c. Overflow alarm: If the displayed count rate is over 999E (999,000 dpm), the OFLO
LCDs blink on the display.
d. Threshold alarm: If the reading exceeds threshold value, the ALr. LCDs and the
reading are displayed alternately, accompanied by an audible beep.
Pressing the SPEAKER/→→→→ push-button mutes the audible alarm, but the ALr. LCDs and
the reading are continuing to be displayed alternately, until the reading decreases to 0.75
from threshold value.
In case the reading exceeds threshold value and then decreases below 0.75 of threshold
value, the ALr. LCDs and the beep sound are automatically cancelled, even though the
SPEAKER/→→→→ push-button has not been pressed.
RAM 100 / Operating Manual Page 12
3.6. Push-buttons Function
Push-button Pressing Mode Function
ON / OFF meter on / off
RESET momentary reading reset
SPEAKER speaker volume modification
MODE long press enter /exit special mode
RESET short press step to next mode (in special
functions)
(exit special functions mode after the
sequence is completed)
SPEAKER/→→→→ Change alarm and/or efficiency value
Enter into calibration mode
(when CAL. LCDs are displayed)
3.7. Battery Replacement
The battery compartment is located at the back of the instrument. To replace the battery,
slide out the battery compartment cover carefully. Use one 9-Volt alkaline battery; ensure
to connect it with the right polarity.
Figure 3-1. RAM 100 Battery Compartment
External Power Supply
The RAM 100 is equipped with external DC input. It can be operated either with a 9V
battery or an external 9V DC power supply. The battery can be used in conjunction with the
external power supply. In case of external power failure the battery supplies the current. The
DC voltage should be 10 to 12 Volts, to avoid drain current from the battery.
RAM 100 / Operating Manual Page 13
4. Calibration
4.1. General Description
The RAM 100 is built of two parts:
a. detector, amplifier and HV assembly.
b. base unit including rate-meter and display.
The amplifier assembly receives 5 Volts from the base unit, to generate high voltage for
the GM pancake tube. The GM pancake tube pulses are amplified in the amplifier
assembly, and sent to the base unit for processing and displaying.
A calibration factor circuitry is built into the amplifier assembly. The calibration factor
adjustment is used to compensate for the GM pancake tube efficiency changes. This
factor usually changes to less than 15% on GM pancake tube replacement, so it can be
ignored when replacement is performed in the field. Nevertheless, when the unit is back
in the lab it should be rechecked and re-calibrated. The replaced GM tube has to be
calibrated (see section 4.2). When the meter is turned ON, the calibration factor value
should be between the ranges of 0.60 to 1.40. In case the factor value deviates from these
ranges, the Err. LCDs blink on the display.
4.2. Calibration Procedure
Note: Calibration should be performed by an authorized technician.
Necessary equipment:
- DVM, adequate HV probe (1:1000)
- Calibration jig or reference source such as 90
Sr/90
Y, 137
Cs, 99
Tc or mix 60
Co/137
Cs
-. DRW #10723-2, PC #1541
a) Open the detector housing by untightening the 3 Philips screws.
b) Connect the detector to the meter.
c) Connect the HV probe to the D1 cathode, see figure 4-2.
d) Turn the meter on. Caution! High Voltage on circuit.
e) Turn R14 to obtain 875 ±5V, see figure 4-2.
f) Place the detector on the calibration jig in its right position, or use a known calibrated
source.
g) Enter calibration mode, see section 3.4 Special Functions. A blinking display
indicates calibration mode.
h) Turn R12 (factor adj.) gradually to obtain on the meter an identical average reading
to that indicated on the jig. The source has to placed against the detector, and the
calibration potentiometer in the detector should be adjusted to obtain the expected
result.
i) Turn the meter off.
j) Put the detector back into its housing. Tighten the 3 Philips screws. The detector is
calibrated and ready for operation.
RAM 100 / Operating Manual Page 14
Figure 4-1. The Amplifier Assembly Electronic Board
HV Measure R14 HV Adjust R12 Factor Adjust
Figure 4-2. The Amplifier Assembly Component Location
4.3. Base Unit Fixed “Calibration”
The base unit counts the input pulses, calculates dead time, averages results and displays
the reading. To check the base unit "calibration" perform the following procedure:
a. Disconnect the detector from the base unit.
b. Adjust the pulser output to obtain a 5 Volts amplitude and 10 µsec width pulse., or use
a standard mini pulser with the pulser adapter.
c. Connect the pulser output to the pulser adapter via a BNC to BNC cable.
Connect the pulser adapter to the base unit via a telephone cable.
d. First turn the meter on, and then turn the pulser on. Set the base unit efficiency to 100.
Obtain the base unit reading (±10%) according to the following Table 1:
RAM 100 / Operating Manual Page 15
Input Frequency
<Hz>
Display (±10%)
<cpm>
50 3000
100 6000
500 30.0E
2764 172E
3176 207E
3960 274E
5063 378E
7650 692E
10692 OFLO
Table 1
4.4. Pulser Adapter – Model A-0270
The pulser adapter converts the "mini pulser" pulses into standard TTL level pulses.
The adapter can be used either with positive or negative pulses. Positive pulses amplitude
should be higher than 0.6 Volts. Negative pulses amplitude should be higher than
1.7 Volts.
The mini pulser can be connected in parallel, either to BNC or MHV input connectors.
The pulser adapter output is connected to the meter’s input.
Figure 4-3. Pulser Adapter Connection Diagram
RAM SURF
Telephone cable
Pulser adapter Pulser
Model A-0270
RAM 100 / Operating Manual Page 16
RAM 100 / Operating Manual
Notes:
Recommended