Tektronix 511 Instruction Manual page 15

In the 2 STAGES position a wide band pre­
amplifier stage is inserted between the INPUT
ATTENUATOR and cathode follower. Since the
bandwidth and transient response of the two
stage amplifier are inferior to a single stage
amplifier, this position should not be used unless
it is necessary, in order to obtain a sufficiently
large image. Risetime is .05 microseconds.
The gain of the two stage amplifier is about
100 (S/N5100 and up, 200) making the maximum
deflection sensitivity approximately .27 vper cm
(.13 v per cm, S/N5100 and up) peak-to-peak.
The deflection polarity is inverted when the
2 STAGES position is used, resulting in down­
ward deflection on the CRT for positive input
polarity.
In instruments S/N845 and up, a three position
lever type switch is mounted at the rear of the
Type 511A Oscilloscope. This switch changes
the operating bias on grid No. 1 of VI9 and the
screen voltage on VI8 and VI9 . With the switch
set at the center (normal) position, the bias
applied to V19 is equal to the bias of V18,
resulting in balanced operation and equal upward
and downward undistorted deflection of the trace.
For normal operation, the DEFLECTION PO­
LARITY switch should be in this position.
While the cathode-ray oscilloscope is usually
employed only as a qualitative rather than a
quantitative device, it is the only instrument
capable of making many types of voltage and
current measurements on non-sinusoidal wave
shapes. To aid in this work the Type 511A
incorporates an internal clipped (unclipped,
below S/N 2406) sine wave voltage calibrator and
associated SIGNAL-CAL IB RATE switch, allow­
ing the operator to select either the internal
calibrating voltage or a suitable external source
of calibrating voltage to substitute for the signal
being measured.
Signal Calibrate Switch
This switch permits the vertical deflection
system of the oscilloscope to be conveniently
changed from the SIGNAL INPUT connector to
two different sources of calibrating voltages.
CALIBRATION
T Y P E 5 1 I - O P E R A T I N G
If it is desired to observe pulses, the switch
should be set in either the upward or downward
position, corresponding to the deflection of the
image on the cathode-ray tube. In the upward
position, the bias of V19 is decreased,resulting
in increased output of VI9 and decreased output
of VI8, thus permitting greater undistorted
upward deflection. These conditions are re ­
versed when the deflection polarity switch is in
the downward position.
Direct Connection to Deflection Plates
To allow direct connection to the deflection
plates with the lowest capacity, banana jacks
(S/N101-454, screw terminals) are provided on
a panel accessible through an opening in the
left side of the case. By removing the jumpers
the interval circuits may be disconnected. The
terminal marked Y1 is the top plate and the one
marked X2 is the right plate. Deflection sen si­
tivity is approximately 27 v DC per cm ( S/N
5100 and up, 13 v DC per cm) on the vertical
plates and 32 v per cm (S/N 5100 and up, 18 v
per cm) on the horizontal.
If positioning control is desired, the jumpers
should be replaced with 1 megohm resistors
and a series coupling capacitor employed. Un­
less balanced input is desired, the unused de­
flection plate should be bypassed to ground.
In the EXT. CAL. position it is connected to
the binding post marked CAL. INPUT, which
in turn may be connected to a source of known
voltage. In the remaining six positions (S/N
2406 and up) it is connected to the center arm of
the CAL. VOLTAGE potentiometer making avail­
able the internal clipped sine wave source of
voltage at power line frequency in six continuous -
ly variable ranges. These six ranges furnish the
following peak-to-peak voltages: 0-.3, 0-1,0-3,
0-10, 0-30, 0-100 V j and are accurate with + or-5
% of full scale for line voltages from 105 to 125v.
For oscilloscopes below S/N 2406 in the re ­
maining three positions the vertical deflection
system is connected to the arm of the CAL.
VOLTAGE potentiometer making available the
internal sine wave source of voltage at power
line frequency in three continuously variable
ranges. These three ranges furnish the following
I N S T R U C T I O N S
P A G E 2 - 5