Sweep Input - Tektronix 511 Instruction Manual

External Sweep Input
Provision has been made for the connection
of external sweep generators to the Type 511 A.
This might be a sine wave oscillator for fre­
quency comparison, the sweep obtained from a
" Frequency sweep" signal generator, etc., or an
auxiliary slow sweep generator. The EXT.
The Type 511A is equipped with a very flex­
ible vertical deflection system capable of ampli­
fying or attenuating as necessary a wide range
of waveshapes. Since the best amplifiers and
attenuators have faults, it appeared undesirable
to first attenuate large signals and then amplify
them back to something like their original
size. It was therefore decided that the Type
511A should have a switching system so that
only as much amplification as needed to get a
reasonably sized image would be employed. This
switch called the INPUT CHAN. SEL. has four
positions, DC, VIA COND, 1 STAGE and 2
STAGES. In the DC position the SIGNAL INPUT
connector is connected via the INPUT AT­
TENUATOR to the upper deflection plate without
a coupling capacitor. The lower plate is con­
nected to the VERT. POSITION control and by­
passed for signals. The VIA COND. position is
similar to the DC except a ,1 |if capacitor is
in series with the deflection plate. On these
two positions the deflection sensitivity is ap­
proximately 27 v per cm (13v per cm, S/N
5100 and up) DC or peak-to-peak AC, with the
attenuator in the XI position.
Normally, connection to the SIGNAL INPUT
is accomplished by attaching the Binding Post
Adapter, which is supplied, and a single lead.
When reduced loading on the circuit under test
is desired, the Input Probe should be used.
CAUTION--THE PEAK POTENTIAL AP­
PLIED TO THE PROBE SHOULD NOT
EXCEED 600 VOLTS.
Since the probe introduces an attenuation of
10X, it will be advantageous to employ a com­
mon shielded lead (no attenuation) to prevent
pickup of stray fields when dealing with very
low signals, if the additional circuit loading is
permissible. A ground lead to the equipment un­
der observation should be provided, and often an
P A G E 2 - 4
VERTICAL DEFLECTION SYSTEM
T Y P E 51 1—O P E R A T I N G
SWEEP INPUT binding post is connected to
the horizontal deflection plates via, the EXT.
SWEEP ATTEN. and a one stage push-pull
amplifier. The entire system is DC coupled,
permitting the use of very slow sweeps. With
the EXT. SWEEP ATTEN. fully clockwise the
deflection sensitivity is approximately 1.5 volts
per cm, DC or peak-to-peak AC.
earth ground is desirable.
Vertical Amplifier
With the INPUT CHAN. SEL. switch in the 1
STAGE position the SIGNAL INPUT connector
is connected to the deflection plate via the IN­
PUT ATTENUATOR, a cathode follower, the
VERT. AMPL. ATTEN., and a one stage push-
pull amplifier. The VERT. AMPL. ATTEN. is
a 500 ohm potentiometer in the cathode of the
cathode follower, allowing the gain of the ampli­
fier to be continuously adjusted over a range of
two to one, thus filling in the INPUT ATTEN­
UATOR steps. Both low and high frequency com ­
pensation is employed to produce a wide band of
uniform amplification. Careful attention has
been paid to the transient response so that square
wave pulses, etc. will be faithfully reproduced.
The amplifiers are adjusted at the factory for
optimum transient response rather than flat
frequency response. A much flatter response is
obtainable if desired by increasing L6, and read­
justing L7, L8, L9, and L10, but overshoot will
occur on steep wave fronts. With optimum tran­
sient response, the risetime (10% to 90% of full
amplitude) is .04 microseconds or better. At the
low frequency end of the band, the top of a
10,000 microsecond square pulse will not depart
by more than 5% from flatness. The deflection
sensitivity is approximately 2.7 v per cm (1.3 v
per cm, S/N 5100 and up) peak-to peak maximum.
CAUTION--CARE MUST BE TAKEN TO
AVOID OVERLOADING THE AMPLIFI­
ERS. THIS WILL BE AVOIDED IF THE
IMAGE IS NOT ALLOWED TO EXCEED
THE RULED SECTION OF THE GRATI­
CULE, WITH THE VERT. POSITION CON­
TROL SET SO THAT WITH NO SIGNAL
APPLIED THE SWEEP LINE IS CEN­
TERED.
I N S T R U C T I O N S