they were formed. Feedback was employed to reduce the chamber voltage as the amount of
radiation increased. Even though the amplifier was linear, the combined effect was to produce
a nonlinear scale on the meter.
The componentsin the indicator unit included a transistor amplifier, a built-in alarm system,
batteries, a built-in calibration source, and a direct~reading meter.
The amplifier had a small current for an input. An output current of up to 1.0 ma operated
the indicator. One feedback potential was developed across the metering circuit and varied
—
TOT
\
5.0
1.0
\
QO
2.0}—
Jaa eee EXTRAPOLATED
\
‘
=
N
\
i
—~—
05
u
s
w
~
TTT
TOT
TT
Lt
°
+
wa
aa
.
—
_~y
S
-
of
4a
.
a oz
w
wn
9°
a
of
.
¥
0.08
—
7
a02-—
or t
Lt
2
tli
Lt tiie
5
10
20
DISTANCE FROM WINDOW INCHES
50
109
Figure 2.11 Calibration curve for 500-curie Co™ source.
from 0 to about 20 volts. Another feedback voltage to the chamber was applied to the positive
end of the chamber voltage battery.
A schematic diagram of the detector and indicator is shown
in Figure 2.14.
There was a built-in alarm system incorporated in the MG-3 unit. When the radiation level
reached approximately 0.5 r/hr, a relay was closed and an alarm buzzer was turned on.
Power for the unit was supplied by six batteries ranging from 1 to 21 volts. The normallife
of all the batteries was 6 months of continuous operation. The battery that operated the alarm
could operate continuously for 18 hours with the alarm turned on.
23