SPECIFICATIONS
TYPE
1231-B AMPLIFIER
AND
NULL DETECTOR
Input Impedance: 1 megohm
in
parallel with
20J.Lj.Lf;
alternate
10-megohm input
available.
Maximum Gain: Greater than 83
db
at
1
kc
with 1-megohm load.
Meter
Scales:
NORM
scale,
calibrated
in
volts
with
accuracy
of ±5%
of
full
scale;
SENS
scale,
calibrated
in
db
with arbitrary zero.
DB
ratios
accurate
within
30%
of
correct
value
in
db, if one reading is above holf
scale.
Null-Detector
Sensitivity:
Less
than
25J.Lv
input
gives
1%
indication
on
meter
at
1 kc.
Amplifier
Sensitivity:
Less
than
8j.Lv
input
at
1 kc for
1%
indication on SENS range
of
meter.
Output Impedance: Approximately 50,000 ohms.
Maximum Output Voltage: 5
volts
into 20,000 ohms; 20
volts
into one megohm.
Open-Circuit Noise and
Hum
Level:
Less
than
0.5
volt
at
full gain, battery operated;
less
than
one
volt, a-c operated with
Type
1261-A Power Supply.
Battery
Life: 200 to 250 hours
at
8 hours a day.
Dimensions: Height, 8 in.; width,
12-1/4
in.; depth,
10-3/4
in.; over-all.
Weight:
23-3/4
pounds, including
batteries,
{cabinet model).
TYPES
1231·P2
AND
-P3
TUNED CIRCUITS
Tuning
Accuracy:
±2%
at
normal
voltage
levels.
Attenuation: At
least
25 db to second harmonic.
Dimensions: Height,
4-1/8
in.; width,
3-9/16
in.; depth, 4 in.; over-all.
Weight:
3-7/8
pounds.
TYPE
1231-P4 ADJUSTABLE ATTENUATOR
Source Impedance: 30 kfl, about equal
to
output impedance of
crystal
detector
in
slotted
line.
Lood Impedance: At
least
1 megohm.
Insertion
Loss:
3 db.
Attenuation Range: 80 db,
readable
to
nearest
tenth db.
Attenuation
Accuracy:
±0.3
db when
operated
between
rated
source
and load impedances.
Additional
errors
caused
by
source
between
14
kfl and
60
kfl
are
less
than
±0.3
db.
Frequency
Error: Negligible below 2 kc.
Maximum Input Power:
1/2
watt.
Terminals:
Input,
Type
938-W
Binding
Posts;
output,
shielded
cable
with
Type
274-NK
shielded
plug to fit
Type
1231-B input terminals.
Accessories
Required: One
Type
874-R34
Patch
Cord for
connections
between
slotted
Iine and attenuator.
Dimensions: Height,
4-1/2
in.; width,
5-1/2
in.; depth,
5-1/2
in.; over-all.
Weight: 2 pounds,
11
ounces.
