Eberline E-520 - SECTION I GENERAL; A. PURPOSE AND DESCRIPTION; B. SPECIFICATIONS

MODEL E-520
SECTION !
GENERAL
A. PURPOSE AND DESCRIPTION
The Model E-520 Portable Geiger Counter combines the
reliability of geiger detectors with new electronic circuits
to provide an instrument with outstanding operational
characteristics in a small, lightweight package at an econ-
omical price. The large, ruggedized meter provides excep-
tional readability and linearity with a variable response
time. Special circuitry yields detector saturation greater
than 1000 R/hr. Calibration stability results from tem-
perature compensation and battery voltage regulation.
High efficiency circuits extend the life of the two D cell
batteries. A rotary switch combines the functions of
power switch, battery check and selection of one of the
five sensitivity ranges. The amplifier driven phone output
may be used with headset, Speaker Assembly (SK-1)
or external pulse counter.
To obtain 5 ranges ( 0-0.2, 0-2, 0-20, 0-200, and 0-2000
mR/hr) two different detector tubes are utilized, one
being located within the case itself for detection of high
level gamma radiation in a range of 0 to 2000 mR/hr. A
tube sensitive to lower level gamma and beta radiation is
located
in
the
hand
probe
used
on
the
four
lower
ranges.
Discrimination
between
beta
and
gamma
radiation
is
made
by
means
of
a
rotary
shield
on
the
probe.
Both
mR/hr
(closed
shield)
and
CPM
(open
shield)
are
presented
on
the meter scale.
Design
features
include:
Pulse
amplifier,
monolithic
integrated
circuit
trigger,
meter
driver
with
variable
response
time,
phone
driver,
regulated
and
feedback
controlled
high
voltage
supply,
and
individual
calibration
controls
for
each
range.
A
single
printed
circuit
board
holds
and
interconnects
all
components
resulting
in
a
minimum
number
of
solder
joints
which
enhances
reli-
ability.
The
printed
circuit
board
connects
to
the
die
cast
cover,
forming
a
completely
operational
instrument
with
controls
and
test
points
exposed
for
ease
of
cali-
bration
or
maintenance.
The
instrument
is
splash
proof
and
dust
proof
and,
with
its
temperature
stability,
can
be
used
under
almost
any
weather
conditions.
B. SPECIFICATIONS
1.
FRONT
PANEL
CONTROLS
AND
CONNECTIONS
a.
RANGE
switch:
Seven
positions;
OFF,
BATT.
CHECK,
X.01,
X.1,
XI,
X10
and
X100.
ORIGINAL
b. Meter:
amperes.
Ruggedized, waterproof, 0-20 micro-
c. RESPONSE control.
d. RESET switch
e. PHONE connector.
f. DETECTOR connector.
2. READOUT
a. Range: 5 linear ranges, switch controlled: 0.2,
2.0, 20, 200 and 2000 mR/hr full scale.
b. Meter Scale: 0-20 mR/hr shield closed and
0-28K
CPM
shield
open.
BATT.
OK
limits
marked
on
meter face.
c. Linearity: 0-0.2, 0-2, 0-20 mR/hr ranges, +8%
of full scale nominal. 0-200 mR/hr range +15% of full
scale
nominal.
0-2000
mR/hr
+10%
of
full
scale
nominal.
d. Response Time: Variable by panel control from
10 seconds to 2 seconds to 90% of final value.
e. Phone: One pulse for each event counted.
Negative pulse approximately 2.5 volts in amplitude,
pulse width determined by range switch position.
f. Saturation Level: Meter will remain at full scale
on all ranges in a field of 1000 R/hr.
g. Voltage Coefficient: Reading changes less than
10% with battery voltage from 3.0 to 2.0 volts (new
batteries to end point).
3. DETECTORS
a. Internal: Small, rugged, halogen quenched.
Cadmium shield surrounding tube for low energy com-
pensation. Sensitivity approximately 100 CPM per mR/hr
for 137Cs.
b. External Probe: (Model HP-177B)
(1)
GM
Tube:
Thin
wall
(30
mg/cm2)
halogen
quenched.