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Sect. IV: Page 4
6) Zero-beat
the frequency
of the Model 606A to
the WWV
signal during a time that WWV
has no
modulation.
Do not disturb the FREQUENCY dial
after this adjustment,
Set CALIBRATE adjustment
to align window.
7) Listen to 1 MC CALIBRATOR with headphones,
If beat-note
is a low audio
tone,
less
than 1 kc,
crystal calibrator is within specifications.
8) Repeat
step
7 using
100
KC
CALIBRATOR.
9) With the CALIBRATOR on 1 MC checkall mega-
cycle marks
on the dial on all bands.
Beat-note
should be within 1% of the dial reading.
606A
4108
Output Level Frequency
Response
Figure 4-5.
C.
OUTPUT
LEVEL
FREQUENCY
RESPONSE
1) Connect AC Probe of @ Model 410B High Fre-
quency
VITVM
to Output
Termination
as shown.
Solder tip of 410B ac probe to center conductor of
UG-290/U
connector.
Clip ground lead of probe
to skirt of connector.
Insert connector into OUT-
PUT connector of Output Termination.
2) Set the output to0.9 volts on the 530 KC-1800 KC
band
and
run the FREQUENCY
dial and RANGE
switch throughout all bands.
The voltage should
not vary more than+11% (1 db) at any output level
setting.
4-6
TROUBLE
SHOOTING
In general,
internal
controls
have
only a limited
range and are designed to compensate
for minor
variations in tubes and/or circuit components.
If
a major section or the complete instrument is in-
operative
adjustment
of
internal
controls
will
seldom,
if ever,
restore
operation.
To
avoid
complications
and reduce ''down time'' locate and
Model 606A
correct the cause of a dead instrument before you
make internal adjustments,
Refer to paragraph 4-1
before making internal adjustments.
A good starting point when repairing a dead instru-
ment is with the power supply.
Check line cord,
both fuses, and the power supply output voltages.
BE SURE TO CHECK THE B+ FUSE IN ADDITION
TO THE MAIN FUSE, ESPECIALLY IF THE OUT-
PUT METER
IS PINNED
TO THE
LEFT,
If you
find a dead power supply tube, tube replacement
will normally restore instrument operation without
any internal adjustments.
However, check the out-
put voltages of each supply to see if the output is
within limits,
Ifthe output is within the limits given
in the Power Supply section donot attempt to refine
the adjustments.
When a section shows up faulty in the above proce-
dure refer to the appropriate section of Table 4-2
and perform the recommended tests.
Ifthe trouble
is in the output termination or attenuator you may
return them separately to the factory for repair.
They are NOT field repairable.
Resistors R9 and R15 in early models were 1/2 watt
resistors which burned out when the variable tuning
capacitors were shorted with dust. If these resistors
burn out replace them with the 5 watt type specified
in the parts list. They are locatedon the turret sta-
tor contacts beneath the chassis and may be replaced
readily without removing the rf shield, IF THEIN-
STRUMENT IS INOPERATIVE, FIRST TRY BLOW-
ING OUT THE PLATES OF THE TUNING CAPACI-
TOR WITH A LOW VELOCITY AIR STREAMSUCH
AS THAT
FROM A VACUUM CLEANER,
Blow out
these plates every time you remove the instrument
from the cabinet for maintenance,
TROUBLESHOOTING CHART, TABLE 4-2
Since the operation of many sections in this gener-
ator is dependent upon the proper operation of other
sections, troubleshooting in this instrument must
be done
in proper sequence.
After determining in
which section the trouble lies, refer to the appropri-
ate
section
of this
chart and perform the tests
indicated.
Also,
if the trouble cannot be found by
any other means,
go through
this chart
from the
beginning. Once the trouble has been found and fixed
do not
continue
on with
the tests in this table,
If output is obtained, troubleshoot the particular
section giving difficulty by referring to the appro-
priate part of Table 4-2, Troubleshooting Chart.
If no output is obtained, the trouble may be amy-
where
in the feedback loop. Refer to Table 4-3,
Troubleshooting
the
Feedback
Loop,
for in-
structions.
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