Sect. I1 Page 2
d. Place signal under test across the INPUT con- duces the severityof the off-scale meter pointer
nector. pinning when an expanded scale is selected.
Four things must be remembered when the ex- 3
e. Step the RANGE switch down from the 100 KC panded scales are used:
position as necessary until the meter pointer rests
1. The setting of the OFFSET controls is arbi-
in the top 2/3 of the meter scale. Decrease the
trary! Any segment may be chosen. However,
SENSITIVITY control and watch for a change in the
only segments which include the input signal are
reading. The reading should remain constant over
useful.
a plateau of control to assure you that noise modu-
lation is not being measured as part of the signal 2. The letter system is a guide to help find the
under test. segment which includes the input signal. It is not
exact. The actual setting may be as much as two
letters away from the indicated setting; especially
It is necessary with unknown input frequencies to
on the X3 scale. This is normal. It does not affect
start the RANGE switch at 100 KC and step down,
instrument accuracy.
because inputs in excess of values on RANGE switch
can overdrive the instrument to display erroneous
readings, i.e.: 2 KC will be erroneously displayed 3. The numbers on the meter scales do in-
on the 1 KC range, but not on 3 KC range and above. dicate specific frequencies because the segment
can be set anywhere along the basic range. How-
ever, if the selected segment includes the input
2B-3 EXPANDED SCALE, GENERAL signal, the pointer indicates the relative position
of the input signal within the segment. If the
The expanded scale feature allows increased accur- segment does not include the input signal, the
acy in the measurement of changes in frequency pointer will be off scale.
by magnifying pointer action. The pointer action is
magnified by expanding to full scale a 30 percent 4. Calibration of the meter scales is determined
segment (X3 setting of the EXPAND switch) or a by the position of the pointer, the basic range
10 percent segment (X10 setting of the EXPAND selected, and the degree of expansion. For ex-
switch) of the range selected by the RANGE ample, if the 1 KC range is expanded X3, the
switch. The particular expanded segment repre- 0-3 scale becomes a 300 cps segment of the
sented by the meter scale is determined by the 1 KC range. If the pointer is placed over the 2.8
concentric OFFSET controls, which move the marker by the OFFSET controls, and it subse-
segment between zero and full scale of the basic quently moves to the 1.3 marker, a 150 cps de-
range. Since the segment selection is arbitrary crease in the input signal is indicated.
and the meter pointer always indicates the value
of the input signal, the meter pointer will be on
scale only if the selected segment includes the
frequency of the input signal. The number of cycles READ BASIC RANGE
FOR INPUT FREQUENCY
in the segment is indicated by the X3 or X10 EXPAND SWITCH 04
READ NUMBER OF CYCLES
on the skirt of the RANGE switch (see Figure REPRESENTED BY METER
2B-2). SCALE WITH EXPAND SWITCH
IN X3 POSITION
A letter system helps find the segment which in-
cludes the input signal; the letters are marked
both on the meter face and around the OFFSET 30 KC
controls. When an unexpanded measurement is
made, the meter pointer indicates a point on the SCALE WITH EXPAND SWITCH
IN XI0 POSITION 100 KC
letter system as well as the value of the input
signal, and the coarse OFFSET control should be
set near that point of the letter system before the
EXPAND switch is actuated. When the EXPAND
XID AND x3 INDEXES REFERENCE
switch is actuated, the meter pointer will be on EXPAND SWITCH POSITION. THEY
ARE NOT MULTIPLYING FACTORS
scale or not far off scale, and slight adjustment LD-Y-33
of the OFFSET controls will set the meter pointer
to the desired place on the scale. Presetting the
OFFSET controls makes it easier to find the Figure 2B-2. Skirt Markings on Range
segment which includes the input signal and re- Switch Dial
00022 -2 |