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[LINE] (HP-IB:
T2) triggers the sweep functions in synchronization with the ac power line frequency,
which is typically 50 or 60 Hz.
[SHIFT] [LINE] (HP-IB:
SHT21 enables penlift, SHT20 disables penlift) generates a penlift signal at
each band crossing. When an HP 8340B/41B sweep crosses frequency bands, the RF is momentarily
turned off at each band crossing which can cause a negative spike on X-Y recorders. To prevent the
negative spike, [SHIFT] [LINE] activates a rear-panel PENLIFT OUTPUT connector that causes the X-
Y recorder's pen to lift at each band crossing. The PENLIFT function works only when the sweep time
is >5 seconds. See Figure 3-18 for information on the rear-panel connector, and the X-Y Recorder
Operating Guide (at the end of Section III) for specific information on X-Y recorder interconnections.
[EXT] (HP-IB:
T3) externally triggers the sweep function. Figure 3-18 explains the rear-panel EXT
TRIGGER INPUT connector and the trigger signal requirements.
[SHIFT] [EXT] (HP-IB:
SHT3) activates the oscillator function. When the red UNLK annunciator
appears in the ENTRY DISPLAY, press [SHIFT] [EXT], which will cause "OSC: REF M/N HET YO N2
NT' to appear in the ENTRY DISPLAY. The flashing cursor indicates which oscillator circuit is not
phase locked, with the remedy found in the appropriate part of Section VIII (Service). Press [SHIFT]
[M5] to cancel this diagnostic function and to return the displays to their previous condition.
INDICATORS
SWEEP green LED lights when the HP 8340B/41B is performing an analog sweep. The LED is off
during all of the following:
retrace, band crossings (band crossings occur at 2.3 GHz, 7.0 GHz, 13.5
GHz, and, in the case of the HP 8340A, 20.0 GHz), during the phase locking that occurs at the start
frequency of each new sweep and each new band, and during manual seeps (since manual sweeps
are synthesized).
RF ON DWELL is a time delay from when the instrument turns on its RF output to when the start of
sweep occurs. In CW mode, this delay determines how long the instrument will wait (after RF power is
activated) before allowing another change in CW frequency. This delay is set at the factor to 400us. If
the HP 8340B/41B is used with test equipment that requires a longer delay, perform the following
command:
Locally:
[SHIFT] [MHz] [1] [7] [Hz]
[SHIFT] [kHz] [#] [Hz]
Where # is an integer value from 5 to 128 (500us to 12.8ms). To determine what
value to enter for a given delay:
Value = Desired Delay (in microseconds)/100
or
Delay = lOOus per count (in the value entry)
Via HP-IB: ''SHMZ17HZ SHKZ#HZ"
Figure 3-11.
Sweep and Trigger Heps (3 of 3)
3-30
Operating Information
HP 8340B/41B
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