Tektronix 485 User Manual

Calibration—485/R485 Service
h. Check all attenuator positions without 20 pF stand
ardizes
68. ADJUST 1 M ft AMPLIFIER HIGH FRE
QUENCY TRANSIENT RESPONSE
a. Set Type 106 to 100 kHz; TD Pulser 2X attenuator
and 50 SI termination. Set CH 1 and CH 2 VOLTS/DIV
to 20 mV.
b. TIME/DIV to 20 ns/div; adjust C55 and R55 for
optimum front corner, C70 for best level behind leading
edge.
69. CHECK COMMON MODE REJECTION 50 S I
and 1 Mft
a. Connect Type 191 Signal Generator to 50 J2 input
CH 1 and CH 2 thru the 10X attenuator and dual BNC
input cable (067-0525-001.
b. CH 1 and CH 2 inputs 50 SI. DC; VOLTS/DIV to
20 mV; VERT MODE to C H I. Apply 8 divisions of
50 kHz.
c. Set VERT MODE to ADD; CH 2 INVERTED. Push
to release CH 2 VARIABLE GAIN and adjust for minimum
deflection; position to center of graticule with CH 2
POSITION control.
d. Set Type 191 to 50 MHz and check for 0.8 div or less
of vertical deflection.
e. Set generator to 50 kHz; inputs to 1 M£2; add 50 SI
BNC terminations at inputs.
f. Readjust CH 2 GAIN for minimum deflection.
g. Set Type 191 to 50 MHz and check for 0.8 div or less
of vertical deflection.
h. Push CH 2 VARIABLE GAIN to CAL.
70. CHECK BANDWIDTH 50 S I and 1 M ft, CH 1
and CH 2
NOTE
Use 6 div o f 3 MHz from the High-Frequency
Constant-Amplitude Signal Generator (067-0532-01)
as reference.
a. Check for minimum of 4.4 div of signal at 350 MHz
in the 50 SI mode.
b. Check 5, 10, 20, 50 mV, and 0.1 V.
c. Check for minimum of 4.4 div of signal at 250 MHz
in the 1 MJ2 mode.
d. Check 5,10, 20, 50 mV, and 0.1 V.
e. Repeat check for 1 V using 4 divisions as reference
and 2.9 divisions the minimum deflection.
71. O P T IO N A L -C H EC K VSWR
NOTE
TEKTRONIX supplies this procedure fo r a 5000-
hour, or as needed, verification o f VSWR. Equip
ment: VSWR AUTOTESTER and Graticule; 56TB/
3A9/2B67; High-Frequency Constant-Amplitude Sig
nal Generator (067-0532-01).
a. Ground 3A9 CH 2 input; connect VSWR Autotester,
VSWR OUT to 3A9 CH 1 input; 3A9 to 20pV/div; DC
coupled; adjust 3A9 DC offset for VSWR = 1.00 on VSWR
graticule.
b. Connect Signal Generator to VSWR Autotester RF
IN through 10X and 5X attenuators. Set generator fre
quency to 100 MHz and adjust amplitude for VSWR =
1.22.
c. Disconnect the Signal Generator and recheck VSWR
= 1.00.
d. Connect VSWR Autotester to 485 CH 1 input; set
485 input to 50 £2, DC coupled.
e. Remove the 10X attenuator and reconnect the
generator to VSWR Autotester RF IN.
f. Sweep the generator frequency from 100 MHz to
350 MHz. VSWR should be less than 1.25 for deflection
factors of 5 mV and 10 mV/div. VSWR should be less than
1.15 for deflection factors of 20 mV/div through 5 V/div.
5-20
REV. C, MAR. 1976

Tektronix 485 Specifications

General

Brand	Tektronix
Model	485
Category	Test Equipment
Language	English