TM
11A625-255-14/TO
33A1-13-170-1
Section Il. OPERATION UNDER USUAL CONDITIONS
3-3. Types of Operation
position which includes the fundamental fre-
a. Spectrum Analyzer TS-723(*)/U acts as
quency of the signal source.
either a spectrum analyzer or a vtvm. It may be
g. Turn the function switch to DISTORTION.
used to make distortion measurements in percent-
h. Adjust the coarse FREQUENCY tuning
age or dB, to search for an unknown input signal
control (upper) until the meter pointer drops
frequency, or, when used as a vtvm, to measure
sharply. If the dip cannot be found, or is not pro-
signals in rfm values or dBm values.
nounced, refer to paragraph 3-7 for instructions.
b. For any type of operation, perform the fol-
lowing procedures:
trol (lower) for a maximum dip of the meter point-
(1) Starting procedure (para 3-4).
er. The tuning becomes sharp as the meter indica-
(2) Procedure for the desired type of opera-
tion decreases.
tion (para 3-5 through 3-11).
j. Adjust the BALANCE control for a mini-
(3) Stopping procedure (para 3-12).
mum meter indication. T h e tuning becomes
sharper as the meter indication decreases.
3-4. Starting Procedure
NOTE
NOTE
The source must put out a stable signal
Check to see that the initial controls
to maintain a steady balance.
settings (para 3-1) have been made be-
fore this procedure is started.
k. Readjust the controls until no further reduc-
a. Preliminary. Set front panel controls as fol-
tion in meter indication can be obtained. As ad-
lows:
justment progresses, decrease the setting of the
(1.) Set the ON/OFF power switch to OFF.
meter range switch to maintain midscale meter
(2) Set the meter range switch to the ap-
deflections.
l. Distortion measurements are read on the
proximate level to be measured. Leave at +50 DB
if level is unknown.
meter in conjunction with the meter range switch.
NOTE
36. Distortion Measurements in Decibels
To obtain accurate results during opera-
tion, ground the spectrum analyzer as
3-5 a through f.
instructed in paragraph 2-5 a .
b. Set the meter range switch to +20 DB.
c. Slowly rotate signal INPUT control clock-
b. Starting.
w i s e until the meter pointer r e s t s a t 0
(1) Throw the ON-OFF power switch to ON;
DECIBELS.
the tuning dial indicator should glow. Allow the
equipment to warmup for at least five minutes.
3-5 g through k.
(2) Check to see that the meter pointer is at 0
e. Distortion measurements are obtained as
on the R.M.S. VOLTS scale.
follows:
NOTE
(1) When the meter range switch is set to
If, during the starting procedure, an ab-
+20 DB, dB distortion measurements can be read
normal result is obtained, refer to table
directly on the meter.
(2) When the switch is set in any other posi-
tion, dB distortion measurements are obtained by
3 5 . Distortion Measurements in Percent-
algebraically adding minus 20 dB and the DB
age
range setting to the value indicated on the meter.
a. Connect test leads from signal source to be
measured to the AF INPUT binding posts.
NOTE
b. Set the AF/RF selector switch to AF
DB measurements for the +20 DB posi-
(TS-723A/U).
tion can also be obtained by the method
c. Set the meter range switch to 100%.
given in (2) above.
d. Set the function switch to SET LEVEL.
e. Slowly rotate the signal INPUT control
(3) Examples of typical dB distortion meas-
urements are shown in table 3-2.
clockwise until the meter pointer reaches a full-
scale deflection of 1.0.
(4) The dB range of each position of the
meter range switch is shown in table 3-3.
f. Set the frequency RANGE switch to the
3-4
