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[ALT] (HP-IB:
ALIn, n = 1-9 turns on the function. ALO turns off the function) causes the instrument
state to alternate on successive sweeps between the current front panel setting and the setting stored
in memory location 1-9. Press [ALT], which will cause "ALT WITH REGISTER: ?" (? is the last used
memory register) to appear in the ENTRY DISPLAY, then press a digit 1-9 to select the desired
memory register. Although the HP 8340B/41B is in the alternate mode, the panel displays will only
show the current front panel state. The power level of the two alternated functions must have the
same attenuator setting,or the attenuator must be decoupled from the ALC (automatic leveling control
circuit) which will allow up to 40 dB of power level difference. This restriction is necessary to prevent
rapid cycling, and subsequent wear, on the mechanical attentuator. See [PWR SWP] in Figure 3-17 for
an explanation of the attenuator and ALC relationship. Press [ALT] again to cancel the alternate
function.
[SHIFT] [ALT] saves the current frequency display multiplication factor as the instrument's default
value. In this mode, pressing [INSTR PRESET] or turning power off and on will not affect the user-
defined frequency display multiplication factor. Refer to the [SHIFT] [START FREQ] command in
Figure 3-7 for more information. This feature can be disabled by pressing [SHIFT] [INSTR PRESET],
which sets the default muliplication factor to 1 and presets the instrument.
[INSTR PRESET] (HP-IB:
IP) causes an internal self-test of the HP 8340B/41B, and initializes the
instrument to a standard starting configuration:
1.
Start sweep at 10 MHz, stop sweep at 26.5 GHz (20 GHz with HP 8341B).
2.
Power level set to 0.0 dBm; however, this level can be reset by changing the calibration constants
(as described in Section VIII).
3. Sweep time to AUTO (44.15 msec) (33.32 msec on HP 8341B).
4. CONT sweep, FREE RUN trigger.
5. All markers set to 13.255 GHz on the HP 8340B and 9.995 GHz on the HP 8341B (center frequency
of the sweep).
6. The checksum of the calibration data is calculated, and if an error is detected then the calibration
data in protected memory is used. If the checksum of the protected data is not correct then default
values are used, and the FAULT annunciator lights in the ENTRY DISPLAY to indicate a calibra¬
tion constant error (press [SHIFT] [MANUAL] when the FAULT annunciator lights, as described in
Figure 3-11).
7. All function values stored in memory registers 1-9 remain in their previous states.
8. A self test is performed, and check LEDs are lighted.
Press [INSTR PRESET] at any time to test the instrument and restore the standard starting condition.
If either of the two red LEDs that are adjacent to [INSTR PRESET] (labeled "INSTR CHECK I/ll")
remain lighted after a preset, the HP 8340B/41B failed the self-test; refer to Section VIII (Service) for
further instructions.
[SHIFT] [INSTR PRESET]: disables the [SHIFT] [ALT] function. This command sets the default fre¬
quency display multiplication factor to 1 and presets the instrument.
Figure 3-12.
Instrument State Keys (2 of 3)
3-32
Operating Information
HP 8340B/41B
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