Tektronix TYPE L, Instruction Manual, Page: 22 / 46

o r two ranges, check the compensation of the
input attenuators. If the distortion occurs on
all ranges, firs t check the compensation of
the probe used. In signal tracing for high-
frequency distortion, consider the loading effect
o f the probe.
Distortion can be divided into two categories:
(1) low-frequency distortion, illustrated in Fig.
4-2 and (2) high-frequency distortion, illustrated
in Fig. 4-3.
(1 ) Any low-frequency distortion in the wave­
form w ill be produced by the X10 am plifier.
(The main am plifier is dc-coupled, and its
response is therefore flat down to dc.)
Low-frequency attenuation w ill produce the
type of distortion illustrated in Fig. 4-2(a). This
type of distortion can be caused by cathode
and screen-bypass capacitors, and by coupling
capacitors. B efore attempting any component
replacement, however, be sure to check the
adjustment of the Lpw Freq. Adj. control
(R6182), as explained in the Calibration
Procedure.
Over-compensation of low frequencies is
illustrated in Fig. 4-2(b). This condition is pro-
m
a
b
F ig. 4-2. (a) Low-frequency distortion caused by attenuation in X 10-am plifier, (b) Waveform distortion
from low-frequency overcompensation in X10-amplifier.
duced by excessive low-frequency " b o o s t".
R efer to the Circuit Description fo r an
explanation of this circuit.
(2 ) Insufficient high-frequency peaking,which
lim its the risetim e and consequently the band­
width, w ill produce the rounded-corner type
F ig. 4-3. (a) Waveform showing insufficient high-frequency peaking, (b) Spiking caused by excessive
high-frequency peaking.
4-6 Maintenance - Type L Plug-In AA