Modulation Meter Calibration; Front Panel Operation Check; Preliminary Check; Frequency Calibration - HP 606A Operating And Service Manual

Model 606A Section IV
Paragraphs 4-11 to 4-18
4-11. FRONT PANEL OPERATION CHECK.
4-12. The following in- cabinet procedures are simple
checks to be performed first whenever difficulty is
encountered in operation of the signal generator.
These checks will isolate the trouble to either the
signal generator or associated equipment and if the
trouble is in the signal generator will isolate it to a
particular section.
4-13. PRELIMINARY CHECK.
4-14. Always perform these check before attempting
to isolate the trouble within the instrument.
a. Turn unit on with no load and allow to warm up
five minutes or more.
b. If output meter is off scale in the negative di-
rection, check for blown B+ fuse.
606A
10 MC CRO
TE Riî
Figure 4-2. Modulation Meter Calibration
4-15. MODULATION METER CALIBRATION.
a. Connect the unit to a 10 mc osilloscope as
shown in figure 4-2.
b. Set RANGE switch to 530-1800 kc band.
c. Set FREQUENCY control to 1000 kc.
d. Set MODULATION SELECTOR to CW.
e. Set ATTENUATOR to 1 VOLT.
f. Adjust vertical sensitivity of oscilloscope to
get 4 cm of deflection.
g. Set MODULATION SELECTOR switch to 1000 % .
Figure 4-3. Waveform for 50% Modulation
h. Adjust MODULATION SELECTOR control until
maximum deflection is exactly 6 cm high ( see figure
4-3). Modulation meter should be reading between
45 and 55%.
i. Check modulation meter calibration from 0 to
90%. It should be accurate within ± 5% of full scale.
4-16. FREQUENCY CALIBRATION.
4-17. The easiest way to check frequency calibration
is with a counter, such as the (9 Model 52-113/C/D
with a 525B plug-in converter. If a counter is not
available proceed as follows:
a. Allow both a receiver capable of receiving WWV
and the Model 606A to warm up for fifteen minutes.
b. Tune in WWV on 5,10, or 15 mc, whichever gives
best reception.
c. Lightly couple a single wire from the RF OUT
jack of the Model 606A to the antenna as shown in
figure 4-4.
606A
c
,
o.
WWV RCVR
LD-11-209
Figure 4-4. Frequency Calibration
d. Tune the RANGE and FREQUENCY controls of
the Model 606A to the frequency of the incoming WWV
signal. The MODULATION SELECTOR switch should
be on CW ( no modulation).
e. Adjust the output level to be about the same as
WWV ( use S meter on receiver if it has one). Too
much signal will block the receiver and obscure the
beat- note.
f. 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 adjust-
ment. Set CALIBRATE adjustment to align window.
g. Listen to 1 MC CALIBRATOR with headphones.
If beat- note is a low audio tone, less than 1 kc, crystal
calibrator is within specifications.
h. Repeat step g using 100 KC CALIBRATOR.
i. With the CALIBRATOR on 1 MC check all mega-
cycle marks on the diál on all bands. Beat- note should
be within 1% of the dial reading.
4-18. OUTPUT LEVEL FREQUENCY RESPONSE.
a. Connect ac probe of
e
Model 410B High Fre-
quency VTVM to output termination as shown in figure
4-5. Solder tip of Model 410B ac probe to center
conductor of UG-290/U connector. Clip ground lead