Tektronix TU-7, Инструкция по эксплуатации

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Circuit Description— Type TU-7
Fig. 3-4 . Tim ing re la tio n sh ip o f w aveform s d u rin g aite rn a te -sw e e p s la vin g o p e ra tio n o f oscilloscopes cap able o f a lte rnate-sw ee p sw itch­
ing. Sweep rate o f Time Base B is set twice as fa st as Time Base A a n d b o th tim e bases are trig g e re d ( p lu g - in ) .
is catenated by the circuit. Thus the slave pulse signal at the
cathode of V102A consists primarily of negative spikes
occurring at the end of each Time Base A sweep.
When V102A and V95A are conducting, the switching
multivibrator is set to display the upper trace. In this state,
the negative slave pulse has no effect on the multivibrator,
since the pulse cannot pass through D102 and does not
affect V102A while it is conducting. However, when V102A
and V95A are cut off, the multivibrator is not set to display
the upper trace. In this case, if a slave pulse arrives, it will
turn on V102A and reset the multivibrator to be ready to
display the upper trace. Thus the upper trace always occurs
immediately following the negative slave pulse and is locked
to the Time Base B sweep.
When the TEST FUNCTION switch is set to the CHOPPED
position, the voltage in the grid circuit of the switching
multivibrator sets the circuit for astable operation. See Fig.
3-5. The switching action begins as soon as supply voltages
are connected, due to slight characteristic differences be­
tween the A and B sections of the tube. The repetition rate
of the multivibrator in the Chopped mode is approximately
100 kc, set by the supply voltages and the resistor-capacitor
combinations in the grid and plate circuits.
As the multivibrator switches from one state to the other,
one output signal is generated in the same manner as the
vertical switching signal in the Alternate mode as D89 turns
on and off. Each time V95A conducts, D89 and D90 are for­
ward biased and D89 shunts to ground any signal applied to
the EXT INPUT connector during the time that the upper trace
segment apears on the crt. Then when V95A cuts off, D89
stops conducting and the lower trace appears on the crt. If
a signal is applied to the input at this time, it will be dis­
played by the lower trace for the duration of the trace seg­
ment. Refer to the discussion of Alternate operation for a
more detailed description of this switching signal.
3-5