HP 608E Operating And Service Manual page 14

Section III
To obtain higher accuracy, a crystal-controlled cali-
brator has been included
to
provide a means of cali-
brating the instrument at any multiple of 1 MHz
between 10 and 270 MHz, or any multiple of 5 MHz
acr088 the frequency range of the instrument. Pl'oce-
dures to crystal-calibrAte the instrument are as
follows:
a. Conduct turn-on procedure8listed in paragraph
3-9.
b. Connect headphone8 (not supplied) to the XTAL
CAL OUTPUT connector (item 26).
c.
Set XTAL CAL switch (item 24)
to
1 MC or 5MC
as applicable.
d. Rotate frequency control (item 18) until MEGA-
CYCLES dial (item 16) is set on the 1 MHz or 5 MHz
checkpoint nearest the frequency to be used.
e. Adjust XTAL CAL GAIN control (item 21) for a
comfortable audio level in headphones.
NOTE
Extraneous beat notes generated by RF
harmonics may be eliminated by properly
setting the RF OUTPUT control (paragraph
3-10, 8tepd) and the XTALCALGAIN control
(paragraph 3-13, step e).
f. Slowly rotate frequency control around the
selected checkpoint until a null (zero beat) is reached.
g. Rotate Cursor Knob (item 3) until cursor is
aligned on MEGACYCLES dial with zero-beat point
achieved in step f.
h. Rotate frequency control until 8elected fre-
quency on MEGACYCLES dial appear8 di-re.:t!y
..;.::::.~.;=
cursor.
i. Set XTALCALswitch to OFF.
3.14. A FINE FREQ control (item 7) is located on the
instrument front panel for making minor frequency
adju8tments. During normal operation no adjustment
of the FINE FREQ control i8 required, and the knob
arrow should be aligned with the front-panel marker.
For a preci8ion frequency selection u8ing a frequency
counter, the FINE FREQ control is used after the fre-
quency has been selected by U8e of the frequency con-
trol. Tuning the knob arrow counterclockwise from
the panel marker lowers the frequency, while a clock-
wise rotation rai8es the frequency.
3-15. POWER OUTPUT CAUBRATION. The RF
leveling circuit in the in8trument maintains a flat RF
output over wide frequency range, with proper initial
adju8tments. The8e adjustments are conducted using
the RF OUTPUT and AMPL TRIMMER controls in
conjunction with the RFOUTPUTmeter. The take-off
point for the detected RF signal displayed on the RF
OUTPUT meter is at the input circuit of the attenua·
tor. Therefore, calibrating the RF output into the at·
tenuator ensures that subsequent operation of the at-
tenuator control will produce an accurate calibrated
RF output from the attenuator. RF output calibration
procedure8 are a8 follows:
3-4
Model 608E/F
a. Conduct turn·on procedures listed in paragraph
3-9.
b. Set the MODULATION 8witch (item 20) to the
CW position.
NOTE
For maximum aCi:uracy, power output cali-
bration8 should be conducted with the in-
8trument 8et in the CW mode.
c. Set the FREQUENCY RANGE switch (item
8)
to
the desired range.
d. Tune the frequency control (item 18) five turn,
in from the low end ofthe selected frequency range as
indicated on the MEGACYCLES dial (item 16).
e. Adjust the RF OUTPUT control (item 5) for an
indication on the RF OUTPUT meter (item 17).
f. Depre88 the AMPL TRIMMER control (item 19)
and tune for a peak RF indication on the RFOUTPUT
meter.
g. Readjust the RF OUTPUT control until the RF
OUTPUT meter pointer ie aligned with the +7 dBm
(ATIENUATOR CAUBRATED) mark.
NOTES
To calibrate range "E" tune to top of band
and repeat step8 e through g, before proceed-
ing on to step h.
The RF OUTPUT control may be adjusted to
a value >+7 dBm (RF OUTPUT meter read-
ing); however, for maximum tube life it is
recommended that the level be reduced when
the higher level is not needed.
h. Tune the frequency control across the selected
frequency range. The RF OUTPUT meter pointer
8hould remain aligned with the ATTENUATOR CAL-
IBRATED mark.
NOTE
If the pointer does not remain aligned with
the ATIENUATOR CALIBRATED mark, the
leveling circuit is not functioning properly.
Stop tuning and readjust the AMPL TRIM-
MER control to restore leveling. The latter
adjustment is made without depressing the
control.
i.
Proceed with operating adjustments listed in
paragraphs 3-18 and 3-20.
3-16. MODE OPERATING PROCEDURES.
3-17. The signal generator8 have four operating
modes identified as CW operation, internal sine-wave
modulation, external sine-wave modulation, and ex-
ternal pulse modulation. In addition, the RF output level
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