Tektronix 7B70 Time Base Instruction Manual page 8

7B70 (SN B205000 and Up)
SECTION 1
Change information, if any, affecting this section will be found at the rear of the manual.
Introduction
the EXT VOLTS I N connector. The sweep free-runs t o pro-
vide a bright base line in the absence of adequate triggering
The 7870 Time Base Unit is designed specifically for use
signal in P-P AUTO and AUTO triggering modes.
with Tektronix 7700-series oscilloscopes. However,
it
is
compatible with all 7000-series oscilloscopes. The 7870
provides calibrated sweeps from 5 secondsldivision to 0.02
microsecond/division. The X I 0 MAGN l F l ER extends the
The Performance Check Procedure given in Section 5
calibrated Sweep t o 2 nanoseconds/division. Sweep rates
provides a convenient method of checking performance of
may be varied continuously (uncalibrated) between calibra- this instrument. The following electrical characteristics
ted steps. Sweep triggering is t o 200 megahertz or vertical apply at an ambient temperature of O' C to +50°c, unless
amplifier bandwidth, whichever is less. The 7B70 features otherwise noted. Warmup time for given accuracy is 20
an external horizontal amplifier t o display signals applied to minutes.
TABLE 1-1
ELECTRICAL CHARACTERISTICS
Performance
Start of Sweep; 12 ns in 7900
Characteristic
S w e e ~ Rate
~
~.
Calibrated Range
Time Interval
1
+ 1 5 ~ ~ t 0 + 3 5 ~ ~ O ~ C ~ O + ~ O ~ C
Performance Characteristic
Excluded Divi-
sions
of
Mag-
I
series, 20 ns in 7704A, 50 ns in
5 secondsldivision to 0.02 micro-
nified Sweep
other 7000 series mainframes.
secondldivision in a 1-2-5 sequence.
End of Sweep; beyond the 90th
X I 0 magnifier extends sweep rate
division
t o 2 nanosecondsldivision.
VARIABLE Range
(uncalibrated)
Sweep Accuracy
Over Center 8
1
Unmag Mag Unmag
I
Mag
Continuously variable between cali-
Sweep Hold-0ff Time
brated sweep rates. Extends uncali-
5 sldiv to 5 psldiv
1.5 times the TIME/DIVISION set-
brated sweep rate to at least 12.5 ting or less.
seconds/division.
0.02 psldiv
Measured in 7000 series mainframe.
External Horizontal
Amplifier
5 sldiv to 0.1
1
sldiv and 0.2
,
3% 3.5% 4%
1
5%
psldiv to 0.02
psldiv
Sweep Length
50 msldiv
1
2%
1
2.5%
3%
1
4%
0.5 psldiv
10.0 divisions to 13 divisions.
Over any 2 div
interval within
center 8 div
Deflection Factor
EXT
VARIABLE
Fully Clock-
wise
25 millivoltsldivision within 5 milli-
volts/division.
VARIABLE
Fully Clock-
I
5%
Scans by ArfekMedia O 2006
250 rnillivoltsldivision within 50
millivolts/division.
1
7%
VARIABLE
Range
wise
A t least 10: 1
1-1