HP (Hewlett-Packard) HP 85660B ユーザーズマニュアル
The Al6 Scan Generator provides tuning voltage ramps to the IF-Display Section (SCAN
OUT and AUX OUT) and scaled ramps to the
OUT and AUX OUT) and scaled ramps to the
Discriminator and A19 DAC.
The SCAN OUT ramp to the IF-Display Section is used for the horizontal sweep signal for
the CRT display update, and the AUX OUT ramp is used by the
the CRT display update, and the AUX OUT ramp is used by the
Video Processor to
maintain video information in proper correlation with the horizontal sweep and frequency
tuning.
tuning.
The scaled ramp to the
PLL2 Discriminator is used to scale the tuning current ramp
(VCO TUNE) used to tune the VCO on the
PLL2 VCO.
Scan time information is placed in the scan time registers U26, U27, and U29. This
information comes from the front panel via the Instrument Bus. Processing of this
information is done on the Al2 Front-Panel Interface and Al5 Controller. The information is
clocked into the Scan Time Register by control signal LSTS (Low = Scan Time Strobe). This
control signal becomes active (low) whenever the selected scan time is changed. A positive dc
voltage is developed by U8 corresponding to the programmed sweep time information applied
to the DAC U28. This voltage is between
information is done on the Al2 Front-Panel Interface and Al5 Controller. The information is
clocked into the Scan Time Register by control signal LSTS (Low = Scan Time Strobe). This
control signal becomes active (low) whenever the selected scan time is changed. A positive dc
voltage is developed by U8 corresponding to the programmed sweep time information applied
to the DAC U28. This voltage is between
V and
V.
The dc voltage level provided by U8 causes a constant current to flow through the proper
scaling resistor, through Virtual Ground and Q5 to the Ramp Capacitor Cl. The scaling
resistor is selected by the programmed sweep information from the front panel the same as is
the sweep time. This information turns on one of the switch drivers
scaling resistor, through Virtual Ground and Q5 to the Ramp Capacitor Cl. The scaling
resistor is selected by the programmed sweep information from the front panel the same as is
the sweep time. This information turns on one of the switch drivers
through
which turns on one and only one of the scaling resistor switches
Q2, Q3, or Q4, to place
the proper scaling resistors in the charging current path for Cl. If the selected sweep time
is slower than 200 seconds, none of the scaling resistors are switched in. For 0.0 to 2.5
frequency span, the waveform on Ramp Capacitor Cl is a positive going ramp from -5.0 Vdc
to -2.0 Vdc with a 3 ms reset time. Ramp Buffer U3 amplifies and shifts the level of the
ramp so that the SCAN OUT is a 0.0 to
frequency span, the waveform on Ramp Capacitor Cl is a positive going ramp from -5.0 Vdc
to -2.0 Vdc with a 3 ms reset time. Ramp Buffer U3 amplifies and shifts the level of the
ramp so that the SCAN OUT is a 0.0 to
V dc ramp.
Al6 1