gamma scientific G-3 User manual

INSTRUCTION MANUAL FOR
MODEL G-3
PHOTOMULTIPLIER PHOTOMETER
Gamma Scientific, Incorporated
3777 Ruffin Road
San Diego, California 92123
REVISED:
May, 1972
Date

CERTIFICATION
Gamma Scientific Incorporated certifies that this instrument was thoroughly
tested, inspected, and found to meet its published specifications when it was
shipped from the factory.
WARRANTY AND CUSTOMER SERVICE
Gamma Scientific's products are warranted to be free from defects in material or
workmanship ... subject to the following terms and conditions:
(a)
PERIOD OF WARRANTY: This warranty shall ... terminate one year ...
after the date of acceptance.
(b)
REPAIR OR REPLACEMENT: Seller's obligations under this clause shall be
limited to repair or correction of any defect of material or workmanship ... in
any such product or to replacement of any defective product or part or unit
thereof, notice of which shall have been given to Seller within the warranty period
specified in subdivision (a) above.
(c)
LIMITATION AS TO REPLACEABLE COMPONENTS WHOSE LIFE IS A
FUNCTION OF USAGE TIME: Since the life of such components is a f unction of
the customer's usage of them, all electron tubes and photomultiplier tubes are
warranted only to the extent that the original manufacturer's warranty applies.
Claims are ... limited to those presented within ... 30 days after occurence pf
any failure.
(d)
CANCELLATION OF WARRANTY: This warranty shall not apply if modi-
fications not authorized by Seller are made.
(e) NO LIABILITY FOR ... OTHER DAMAGES: In no event will Seller be liable
for any incidental, consequential or other damages, and liability is restricted to
the matters and extent herein set forth.
The warranties set forth in this clause are in lieu of any other warranties, ex-
pressed or implied, which the purchaser or others might have under or arising -
from this agreement, by statute, at law, in equity or otherwise, INCLUDING ANY
WARRANTY OR MERCHANTABILITY OR FITNESS. Goods sold subject to above
warranty only, and Seller expressly denies any other warranties or representations,
statutory, legal, or equitable, expressed or implied.
Gamma Scientific Incorporated provides repair services for all Gamma products.
A complete, modern Service Department, Stock Room and Calibration Facility is
employed at the factory.
In the event the G-3 and/or the fiber optic probe does not function properly or is
damaged, Gamma Scientific Incorporated should be contacted with regard to the
I.

specific symptoms of the problem. Note: For all service requirements, please
ask for the customer Service Department.
Gamma Scientific must be contacted prior to any return shipment of equipment.
Failure to do so will result in delayed return to the customer.
Warning:
The circuitry of the G-3 utilizes highly specialized semi-conductor
devices. Trouble shooting by a person not familiar with the circuits may result
in extensive damage to these components
and should not be attempted.

TABLE OF CONTENTS
SUBJECT
PAGE
1.
INTRODUCTION
1
Description
1
Specifications
1
Accessories Supplied
1
II.
INCOMING INSPECTION AND PERFORMANCE CHECK
2
Incoming Inspection
2
Performance Check 2
ILLUSTRATIONS
FIGURE
PAGE
1
Model G-3 Photometer with probe
IV

I. INTRODUCTION
Description
The Gamma Scientific Model G-3 Photometer is a self-contained high sensitivity
laboratory instrument. Its detector is a photomultiplier with an S4 photosurface.
The adjustable high voltage power supply and a sensitive FET electrometer am-
plifier in conjunction with a variable neutral density shutter and 5 to 1 scale
expansion provide for maximum range. The G-3 is supplied with a detachable
high spatial resolution flexible fiber optic probe. Other features include rugged
design, ease of operation and a built-in shutter for zeroing. State-of-the-art
solid state components are used throughout the unit. The "Se nsitivity Control"
and "Zero Control" are both 10-turn potentiometers for fine vernier adjustment.
The instrument is housed in a fully isolated and insulated shock-proof and shatter-
proof case. There is a 1/4-20 thread connection on the bottom of the case for
tripod or optical bench mounting.
Specifications:
Sensitivity:
Presentation:
Scale Expansion:
High Voltage:
Detector:
Zeroing:
Power:
5 x 10 -3
footcandles with a probe diameter of 0.5".
A.
Taut band meter (scale 0-100 and 0-20)
B.
Output jack for external meter.
5 to 1
Adjustable 200 to 900 volts.
S4 photosurface.
Built-in shutter, adjustable from closed (decreasing in
density) to open.
105-125VAC, 50-60Hz.
Accessories Supplied:
Detachable fiber optic probe.
External output cable with plug.
Instruction manual.

II. INCOMING INSPECTION AND PERFORMANCE CHECK
Incoming_Inspection
Physical and Mechanical Check: If damage to the shipping cartons is evident, re-
quest that the carrier's agent be present when the instrument is unpacked. Inspect
the unit for scratches, dents, cracked lenses, broken knobs, etc., and also for
mechanical damage.
Performance Check
The electrical and mechanical performance check should be verified as soon as
possible upon receipt.
1.
Initial Control Setting
s(before AC_power is
qp
.
plieci).
Shutter - Full ccw (closed.
"Zero Control" - Centered (10-turn control, turn 10 turns in one direction than
back 5.
"Range" - "0-100".
"Sensitivity Control" - Full ccw (10-turn control).
2.
Plug the G-3 primary power cord into a 105-125 VAC, 50-60Hz line. Scale
should now be illuminated. (Meter reading may or may not be on scale.) •/
3.
Adjust "Zero Control" cw and ccw. Meter reading should increase and decrease
respectively. Leave with a meter reading of "20" on the 0-100 scale.
4.
Turn "Range" switch to "0-20". Meter reading should increase to "20" on the
0-20 scale.
5.
Turn "Range" switch to "0-100".
•
6. Insert fiber optic probe into the optical input and secure with retaining ring.
7.
Turn shutter slowly from full ccw to full cw. Meter reading should
gradually
increase. If the meter goes off scale, decrease the light input entering the fiber
optic probe. Turn shutter ccw until a mid-scale reading is obtained.
8.
Turn "Sensitivity Control" slow cw. Meter reading should increase. Leave
adjusted for a full scale ("100") reading.
9.
Insert the supplied cable into the external output jack.
10.
Connect opposite end of cable to high impedance external meter. With a full

scale reading on the G-3, the external output should be 150mv.
11. Turn shutter full ccw.
12. Remove primary power plug from the AC line.

OPERATING PROCEDURE AND USE
Operating Procedure
1. Initial control settings (before AC power is applied).
A.
Shutter Closed (full ccw, white line indicator away from probe receptacle).
B.
"Range" control to "0-20" position.
C.
"Sensitivity Control" to minimum (approximately 10 turns in a ccw direction.
Note: This control has a "slip type" stop at each end of travel, therefore, it is
difficult to feel when the control is at either extreme. By turning approximately
10 turns, you are assured of being at the minimum or full ccw end of travel.
D.
"Zero Control" to mid-range of travel. Turn approximately 10 turns in
a ccw direction and then 5 turns in a cw direction.
E.
If desired, mount the G-3 on a tripod or an optical bench by means of the
1/4-20 threaded receptacle in the bottom of the G-3 case. The G-3 has been
designed so that when mounted on an optical bench, the energy from a source will
be in proper alignment (through the fiber optic probe receptacle - with fiber optic
probe disconnected) with the photocathode of the photomultiplier detector. The
meter face and operating controls are easily accessible but don't interfere with
the incident rays reaching the detector.
F.
If the fiber optic probe is to be utilized, insert the probe connector into
the G-3 optical input (probe) receptacle and tighten the probe connector retaining
ring.
-
2. Plug the G-3 power cord into the 105-125 VAC, 50-60Hz line. The photometer
is very well isolated from the AC line power. In addition, the case is isolated
from the internal circuitry. Note: When the power cord is plugged into the AC
line, the G-3 is turned on. For this reason, make sure the power cord is un-
plugged when the photometer is not being used.
3. Adjust the "Zero Control" for a 0 (zero) meter reading. Note: If the meter
pointer is above 0 (zero), turn the control ccw until the proper reading is obtained.
If the meter pointer is below 0 (zero), turn the control cw.
4. Turn the "Range" control to "0-100" (the meter pointer will remain at 0 (zero).
5. Aim the fiber optic probe tip or the optical input receptacle toward the source
or surface to be measured.
6. Turn the shutter control to open cw with white line indicator in direction of
fiber optic probe (optical input receptacle).

7.
If the meter pointer is not within the 0-100 range on the scale, the intensity
of the input is too high. To bring the pointer between 0-100, attenuate the in-
put by means of the neutral density filter in the shutter (full cw - open, increasing
to closed - full ccw).
8.
Adjust, as necessary, the "Sensitivity Control" in a cw direction (increasing
the high voltage applied to the photomultiplier) to obtain the desired reading, for
instance, 100.
9.
Turn shutter to closed (full ccw).
10.
Adjust the "Zero Control" for 0 (zero) on the meter. NOTE: Each time the
"Sensitivity Control" is adjusted (either cw or ccw), the zero should be checked
and adjusted if necessary. Remember, by turning the "Range" control to "0-20",
a more sensitive 0 (zero) adjustment can be made. When the unit is adjusted
for 0 (zero) on the "0-20" range, it will also be adjusted on the "0-100" range.
When 0 (zero) is adjusted on the "0-100" range, it may or may not be exactly 0
(zero) on the "0-20" range. Hence it is always the best procedure to adjust zero
in the 0-20 position of the meter range switch.
11.
Turn shutter to open (full ccw) or to desired attenuation position (see Step
7).
12. Readjust, if necessary, the "Sensitivity Control" for the desired reading,
i. e., 100.
13.
Repeat Steps 9, 10, 11 and 12 as necessary to obtain the desired "Relative
Intensity" reading and proper 0 (zero) reading.
Use
The G-3 Photometer is now ready to be used to measure the relative intensity of
the unknown source or surface. Allow 15 minutes warm-up time (to stabilize the
electrometer amplifier) before taking any measurement data. When the meter
pointer is reading 20 or below on the 0-100 scale ("Range" control in "0-100"),
the "Range" control may be turned to the "0-20" range, thus producing a full scale
reading of 20 decreasing down to 0.
NOTE: As the "Sensitivity Control" is turned cw (increasing high voltage), the
noise, inherent in the photomultiplier tube, will become evident and show as
minor fluctuation on the meter pointer. This fluctuation is normal operation of
the G-3 when operated near its maximum sensitivity.
External Output Jack
The external output jack has an impedance of 1.5K ohms. The output circuit is
capable of driving any high impedance accessory instrumentation.
-5-

The output is 150mv when the G-3 meter is reading full scale. NOTE: The 5
to 1 range expansion ("Range" control is not functional with regard to external
output). The meter is isolated from the output jack, thus the meter may be
read simultaneously with external output instrumentation.
The output circuit has a 1.1 second response with a frequency cut-off of 0.32Hz.
The output circuit is isolated from the AC line by means of the AC power trans-
former.
Precautions
1. Do not apply any voltage to the external output jack.
2.
The instrument case is molded of a high temperature alloyed thermoplastic.
It is more resistant than most plastic materials to all chemicals. However, care
should be taken to avoid contact with alcohols, keytones, or other active organic
solvents.
3.
The meter cover is made of polycarbonate and is also solvent sensitive. Avoid
abrasive substances when cleaning the meter face. A simple moistened cloth is
better than cleaners of the "Windex" type.

R5
Fl
Pt
[ ZERO
SCHEMATIC DIAGRAM
MODEL G -3 PHOTOMETER
02 MA 1Z 72-

PARTS LIST FOR
.
G-3
DATE March 1972
BY ELLD
. , •••• Ir, r. ..
DESIGNATION
DESCRIPTION
I MANUFACTURER
Id 1 #7741393 Integrated Circuit Adv. Micro Devices
Q1 Transistor 2N5139
Fairchild
Q2
Transistor 2N5323
RCA
Q3
Transistor U235
Siliconix
Q4
Transistor 2N5486
Motorola
Q5 .
Transistor 2N3427
Motorola
,
D1,2
Diode #SD-1
Diodes Inc.
D3,4
Diode 1N5231
Motorola
D5
Diode HV-20
Semicon
R1
Resistor 47K 1 / 2
W 10%
Wescom
R2,3
Resistor 750 ohm 1/2W 10%
Wescom.
R4,8
Resistor 5.1K
1 / 2
W 10%
Wescom
R5
Resistor 51 ohm 1/2W 10%
Wescom
, R6,7, 9,10 Resistor 2.7K
1 / 2 W 10%
Wescam
R11 Resistor 100 ohm 1/2W 10%
Wescom
R12
Resistor 150 IC
1/2W 10%
Wescom
R13 s Resistor 1 Meg Reverse Log Pot. CTS .
R14,1,16,
20,21
22 Resistor 15 Meg 1/2W 10% Wescom
R17 Resistor 39 ohm 1 / 2 W 2%
Corning
R18 Resistor 1K 1/2W 2% .
Corning
R19
Resistor 150 ohm
1 / 2 W 2%
Corning
R23 - R32 Resistor 4.7 Meg 1 / 2 W 10%
Wescom
R33 Resistor 500 ohm linear pot.
CTS
R34
Resistor 1K
1/2W 10%
Wescom
C1,2
Capacitor 470-25V CE02W
Elna
i
C3,7 Capacitor 100-15V U15-100
Wescom
C4
Capacitor 2-15V T15-2
Wescom
C8
C5,6 Capacitor .1-100V EW-11
Wescom
Capacitor .33-12V AY-375
Sprague
C9
Capacitor .01-100V CDEW0010
Wescom.
C10
Capacitor .01-1600V DD16-103
CRL

DATE March 1972
BY
eELLD
PARTS LIST FOR G-3
C... ACUI T
DESIGNATION
DESCRIPTION
MANUFACTURER
Power Cord #17205 Belden
P1
Fuse #318001 1.0Amp Little Fuse
Neon Lamp #NE-2H
G. E.
Fl
L1
Transformer #TF121C
Wescom
Ti
Meter
- #841-16315 0-1 ma_
Phaostron
M1
Switch #1460
Centralab
Si .
Transformer #TY200X
Triad
T2
Jack #142A
Switchcraft
J1
Photomultiplier Tubt931A
R. C.A.
NT1