Trigger Level; Selecting Sweep Rates - Tektronix 7B53A Instruction Manual

-
_moll
SWI'
tAl
At • •
u
[~
..
{ij
VARIABLE - I'IU , . . _ . . ,
TlME/ DIV OR DLY TIME
Operating Instructions-7853At7853AN Operators
TIME/ DIV DR OL V T IME switch
BrllCkeu enclose main swee p rllte or de-
lay time {depending on Display Model
OL V'O T ime/ Division
swi tch
Selects MA.IN SWP, INTEN , and DLV ' D
.o--ll~-----
SWP Dlspl,ly Modes
DU'D TtlIS
III
Dot indicues delByed sweep rate
VA RIABLE cont rol
Varies main sweep
rate~,
de{ayed sweep
r.tes, or main sweep holdoff; dependi"9
on th e connection of P140 linternall
SelecH MI XED ~ispl ay Mode
Fig , 1-7 . Composi" T ime/Division switch ,
Trigger Level
The MAIN TR IGGER LEVE L control determines the
voltage level o n the trigger signal at which the sweep is
triggered . When the l EVE L control is set in the
+
region ,
the trigger circu it responds at a more positive point on the
trigger signal. When the LEVEL control is set in the
- region, the trigger circu it responds at a more negative
point on the trigger signal. Fig. 1-6 illustrates this effect
with different sett ings of the SLOPE switch.
Before setting the MA IN TR IGGER ING LEVEL, set the
desired SLOPE, MODE, COUPLING, and SOURCE. Set the
LEVEL control fully counterclockwise and then rotate
clockwise until the display starts at the desired point.
Selecti ng Sweep Rates
The T IME / DIV OR DL Y TIME switch selects calibrated
sweep rates for the main sweep generator and the Dl Y'D
Time/Division switch selects calibrated sweep rates for the
delayed sweep generator. The sweep rate of the main sweep
generator is bracketed by the b lack lines on the clear plastic
flange of th e TlME/ DIV OR Dl Y T IME switch (see Fig.
1·7). The SlNeep rate of the delayed sweep generator is
indicated by the white line on the DLY'D Time/ Division
knob . When the Tl ME/ DIV OR Dl Y TI ME switch and the
Dl Y'D Time/Division switch are set to the same sweep
rate, the switches lock together and the sweep rate of both
generators are changed at the same time. However, when
the Dl Y'D T ime/ Division knob is pulled outward, the clear
plastic flange is disengaged and on ly the delayed sweep
generator S1Neep rate is changed. This allows changing the
delayed sweep rate with out chang ing the delay time
determined by the main sweep generator. The Dl Y'D
Time/ Division SlNitch also selects Display Modes. See
Display Mode d iscussion in this section for further informa·
tion .
A VAR IABLE control is provided concentric with the
TIME/ DIV OR DlY TIME and the DLY'D Time/ Division
switches (see Fig . 1-7). When the VAR IABLE control is
rotated clockwise to the CAL position (into switch detent)
the variable function is inoperative and the VAR IABLE
knob can be used only to select the MIXED Display Mode
(see Display Mode discussion in this section for more infor-
mation) . However, when rotated counterclockwise (out of
switch detent). the VARIABLE control is activated for
variable (uncalibrated) main sweep rates, delayed sweep
rates, or main sweep holdoff; depending upon the setting of
the Variable Selector multi-pin connector (see Fig. 1·3) .
The VAR IABlE control allows the sweep rate in each
Time/Division switch position (main or delayed) to be
red uced to at least the next adjacent switch position and
the holdoff time to be increased 2: 1.
®I
REV. APR
1974
' ·11