Tektronix 1S1 Instruction Manual page 94

g. Adjust the Type 1S1 mVolts/Cm VARIABLE control for
a display amplitude of 5cm on the fast-rise portion of the
waveform.
h. Pull out on the MAGNIFIER knob and turn the TIME
/CM switch to .1 nSEC.
i. With the TIME POSITION and FINE controls, position
the pulse rise on the graticule as indicated in Fig. 5-35B.
j. Check the risetime of the Type 1S1 as indicated in the
display. Risetime should be 350 psec or less (but not less
than 330 psec). Since the risetime of the tunnel diode pulse
generator output is less than 1/10th the risetime of the
Type 1S1, the pulse generator risetime may be considered
neglible.
k. If risetime was found to be greater than 350psec:
1. Adjust R85 (SNAP-OFF CURRENT) for a risetime of
340psec. (Turn the control counterclockwise to decrease
risetime.) Do not decrease risetime below 330psec, since
this will adversely affect the transient response of the
system. See Fig. 5-33 for the location of R85.
2. Remove the pulse generator from the Type 1S1
SIGNAL IN connector.
3. Reset the following Type 1S1 controls:
TIME/CM
TRIGGER SOURCE
mVolts/Cm VARIABLE
4. Readjust loop gain as described in steps 18 j
through 18 v. (Use a 5X attenuator and the variable
attenuator.)
If risetime cannot
psec range with R85, it may be necessary to read-
just R22 (BRIDGE VOLTS). (See step 19.) Set R22
for a slightly higher voltage (clockwise) to de-
crease risetime, then readjust R85 and R135 as
described previously. Keep in mind, however, the
noise limitations caused by increasing the bridge
voltage.
l. Disconnect the input signal from the Type 1S1 SIGNAL
IN connector.
m. Turn off the tunnel diode pulse generator.
NOTES
Calibration – Type 1S1
5 nSEC
INT +
CAL
NOTE
be adjusted to the 330-350
5-31