Table
5M5.
Distortion Test.
FREQUENCY FREQUENCY
DISTORTION
RANGE
DIAL
Part A
XIO
1
less than 1 %
X 100
1
less than 1 %
XIK
1
less than 1%
XIOK
1
less than 1%
XIOOK
I
less than 1%
XIOOK
5
less than 1 %
Part B
XIM
2
less than 1 %
XIM
5
less than 2%
XIM
10
less than 4%
2 + . . .
2 + E3
% distortion
=
E,
El
=
rms voltage of fundamental frequency;
E2
rms voltage of second harmonic;
E3
fillS
voltage of third harmonic;
etc
• . . • .
g. Perform Minimum Distortion AdjusL'11ent, Paragraph
5·39, if tolerances are not met.
5- 1 8. Hum and Noise Test (Optional).
a. Connect ac voltmeter to 50 ohm output of 652A as
shown
in
Figure 5·2.
b. Set 652A controls as follows :
FREQUENCY RANGE
. • . . . . . . . . . . .
X l OO
FREQUENCY dial . .
. . •
.
. . . . . . . . . . • • •
10
OUTPUT ATTENUATOR
. . . . . . • • • •
3.0 V
OUTPUT MONITOR
. . . . . . . • • . • •
NORMAL
TEST OSCI LLATOR
hP652A
@
$@ @I:��
50 OHM
FEED THRU
hPI I048C
652A"S··IIS2
c. Adjust 652A OUTPUT AMPLITUDE and VERNIER
controls for a reading of 0 dB on 3 V range of ac voltmeter.
d. Remove top cover of 652A and short out tuner by
clipping a lead from fbe solder lug on tuner frame to
chassis.
Lead dress is critical to frequency accuracy
and flatness.
Residual hum and noise should read greater fban · 66 dB
from 0 dB reference set on rms voltmeter in Step c.
e. Remove clip lead and replace 652A top cover.
5-19. Amplitude Stability Test (Optional).
a. Connect ac differential voltmeter and strip chart
recorder to 652A as shown in Figure 5·6.
NOTE
Float ac differential voltmeter by using an
isolation transformer to isolate chassis ground
from ac power line ground.
o.
Set 652A controls as follows :
FREQUENCY RANGE . . . . . . . . . . . . . . XI K
FREQUENCY dial . .
•
.
• . . . . •
.
. • . . •
.
. • •
1
OUTPUT ATTENUATOR
.
. . . . . . • . •
3.0 V
OUTPUT MONITOR
. . . • . . . • . • . .
NORMAL
c. Adjust 652A OUTPUT AMPLfl"UOE and VERNIER
controls for a 3.000 V indication on differential voltmeter.
d. Set recorder output adjustment of ac differential
voltmeter so that a
±
0.06 V variation of 652A output can
be easily recorded.
e. The output of 652A should not vary by more than
±
2% over a period of one month when temperature
remains between 200e and 30°C.
STRIP CHART
RECORDER
h P680
REAR PANEL
AC-DC DIFFERENTI A L
VOLTMETER IDC STANDARD
hp 74 1B
@ @
oLSJ
0
@
0
@ @ @ @ @ @ @@
@ @
Figure
5-6.
Amplitude Stability Test.
5·7
Model 652A
Sect.ion V