Shift M4; Shift M5; Shift Rf; Shift Meter - HP 8340B Manual

SHIFT M4
(HP-IB:
SHM4)
SHIFT M4 activates 32 service diagnostic routines that test some of the DACs and much of the control
circuits on the
A27
level control,
A28 SYTM
driver,
A57 marker bandcross, and ASS
sweep generator
assemblies. This diagnostic also allows the results of the self test, run at power on and after
instru¬
ment preset, to be displayed
in the front panel ENTRY DISPLAY.
The DAC
tests are not
exhaustive
(a small error does not
generate a
failure indication), but
if
a
test
fails,
the indication should direct you to
a
specific device or circuit path.
While the tests are running, the
DIAGNOSTIC TEST IN
PROGRESS
appears
in the front panel
ENTRY
DISPLAY. When the
tests finish,
TEST:? FULL DIAGNOSTIC
and then
PASS or FAIL appear. Pass
indicates
that all tests related to this diagnostic
passed.
Fail indicates that one
or more
tests failed.
See
the controller section functional group for details on the
SHIFT
M4
diagnostics.
SHIFT M5
(HP-IB:
SHM5)
SHIFT M5
turns
off
any of the above diagnostic routines, and restores the
displays to their
previous
condition.
SHIFT
RF (HP-IB:
SHRF)
SHIFT RF disables the ALC (automatic leveling control) to allow direct control of the linear modulator
circuit.
When
SHIFT RF
is engaged, there is no limit on the minimum pulse repetition
frequency
1.
Press [SHIFT] [RF]
POWER SEARCH:X.XXdB appears
in the entry display (X.XX is the last-entered value).
2.
Place the instrument in
CW, or
in
pulse modulation mode with pulses wider than
2
(AS.
3.
Using the step keys, the data entry keyboard, or the front panel knob, set the desired power level.
The POWER
dBm display shows
the actual
power when
the
instrument
is in the
CW
or pulse
modulation mode.
SHIFT RF
can also be
used as
a
diagnostic function of the ALC
circuits.
SHIFT METER
(HP-IB:
SHA3)
This function bypasses the ALC
to allow direct control of the linear modulator
circuit. In this
mode,
there
is
no
limit on the minimum pulse repetition
frequency.
1.
Press
[SHIFT] [METER].
ATN: X-xx
dB,
MOD; x.x dB appears
in the
ENTRY DISPLAY
(x is the last-entered value).
2.
Place the instrument in
CW, or
in
pulse modulation mode with pulses wider than
2
ps.
HP 8340B/41B
Assembly-Level Service Front Panel Diagnostics A-29