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INT/EXT SWITCH & BNC CONNECTORS select either the internal (INT) 10 MHz crystal oscillator
frequency standard, or an external (EXT) frequency standard to be used as the master timebase for
the HP 8340B/41B. To select the internal standard, place the switch in the INT position and connect a
jumper cable between the INT and EXT BNC connectors (the INT BNC is now outputting 10 MHz at +3
dBm). To use an external standard, disconnect the jumper, change the switch to EXT, and connect the
external source to the EXT BNC connector. The external source must be either 5 MHz ±50 Hz or 10
MHz ±100 Hz, and provide 0 to +10 dBm into the 50Q BNC connector. When the switch is in the EXT
position the amber EXT REF annunciator lights in the ENTRY DISPLAY.
EXT TRIGGER INPUT triggers the start of a sweep. Trigger signal must be >2 volts (10 V maximum),
and wider than 0.5 psec. Nominal input impedance is 2 K£1 Figure 3-11 describes the front panel
procedures that are involved in sweep operations.
MUTE OUTPUT causes the servo motor of an X-Y recorder to pause while the HP 8340B/41B crosses
a frequency band switchpoint. The X-Y recorder Operating Guide, located at the end of Section III,
explains the interaction of recorders with the HP 8340B/41B.
PENLIFT OUTPUT. For operation with X-Y recorders. PENLIFT disables an X-Y recorder's ability to
lower its pen during sweep retrace. If [SHIFT] [LINE] is pressed on the front panel, PENLIFT will also
disable the pen during forward sweep band switchpoints. Because of X-Y recorder limitations PEN¬
LIFT will always disable the X-Y recorder's pen at sweep times under 5 seconds.
PENLIFT enables pen operation by providing a current path to ground for the X-Y recorder's pen
solenoid. The voltage at the PENLIFT output in this state will be approximately 0 Vdc. Circuit imped¬
ance in this state is approximately .5 Ohms.
PENLIFT disables pen operation by not providing a current path to ground for the X-Y recorder's pen
solenoid. The voltage on the PENLIFT output will be equal to the X-Y recorder's pen solenoid supply
voltage. Circuit impedance in this state is very high.
NEG BLANKING provides a negative rectangular pulse (approximately —5 volts into 2 K£2) during
retrace and band switchpoints when the HP 8340B/41B is sweeping.
Z-AXIS BLANK/MKRS supplies a positive rectangular pulse (approximately +5 volts into 2 K£2) dur¬
ing the retrace and switchpoints when the HP 8340B/41B is sweeping. This output also supplies a -5
volt pulse when the RF output is coincident with a marker frequency (intensity markers only, as
explained in Figure 3-9).
STOP SWP IN/OUT abruptly stops a sweep when this input is grounded. Retrace does not occur, and
the sweep will resume when this input is ungrounded. The open circuit voltage at this connector is TTL
High, and is internally pulled low when the HP 8340B/41B stops its sweep. Externally forcing this input
High will neither cause damage nor disrupt normal HP 8340B/41B operation.
Figure 3-18.
Rear Panel BNC Connectors (2 of 2)
HP 8340B/41B
Operating Information
3-43
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