Tektronix FG 5010 User Manual

Theory
of
Operation -
FG
5010
OUTPUT SECTION
INTRODUCTION
The Output Section is depicted on Diagrams 24 , 25 , 26 ,
and 27. The major circuits depicted are the Digital Control
circuits , the Level Control , the AM Circuit , the Output
Amplifier , the Step Attenuator , the Offset Generator , and
the Power Supplies . The Output Section amplifies ,
modulates , offsets , and attenuates the signal from the Sine
Shaper circuits . The Output Section also furnishes the
voltages
necessary to
operate
the Offset
Generator .
Since the Digital Control circuits are depicted on several
diagrams , the circuits are discussed here as one unit , rather
than being discussed with the various other circuits . Refer
to the Digital Control Circuit discussion following the Block
Diagram Description . In addition , although the Power
Supplies depicted on Diagram 27 are physically a part of the
Output Amplifier circuit board assembly , the description of
the supplies is grouped with the other power supply
descriptions , just following the Trigger , Phase Lock , and N
Burst Circuits discussion later in this section .
BLOCK DIAGRAM DESCRIPTION
Refer to
the
Output
Amplifier Block
Diagram just
preceding
Diagram 24.
From the
Function
Selector in the
Sine
Shaper
Section
, the
sine ,
square
,
or
triangle -
wave
signal is applied to the Level Control Circuit . Gain of the
circuit is
controlled
by the
CPU to
conform
to front -
panel or
remote requirements . This section of the circuitry and the
Step Attenuation circuits are the amplitude - setting elements
of the FG
5010. The AM
input signal from
the front -
panel
connector is applied to the AM circuit , which buffers the AM
signal , and sums it with the fine amplitude control voltage
that sets the gain of the Level Control circuit . If no AM signal
is applied , only the Fine Amplitude Control voltage is applied
to the Level
Control
. The
Level
Control also
complements
the
signal
upon CPU
command .
From the Level Control , the amplitude - controlled signal is
fed to the amplifier , which is a current - driven amplifier that
has a gain of approximately 3.3 V per milliampere . The +
and 16 V supplies furnish the power to drive this circuit .
The
output of the
amplifier
is
connected to a
three -
segment
step
attenuator
, again
controllable by the CPU
. The circuit
provides attenuation to the applied signal in 10 dB steps to
a maximum of 50 dB . The output of the Attenuator is
applied with the offset voltage to the Output Switch .
The Offset Generator produces the offset current of
either polarity that is applied with the output signal to the
Output Switch . Both polarity and amplitude of the offset is
4-32
controlled by the CPU through the latch . The Output Switch ,
upon CPU command , connects or disconnects the signal
and offset from the Output connector .
DIGITAL CONTROL
The Digital Control Circuits receive the data from the
CPU , store it , and upon command , apply the data to the
controlled circuits . The circuit consists of five latches , which
are
connected to
form
40 - bit serial - parallel shift register .
These are as follows : Latch U1642 controls eight of the ten
increments of DAC U1751 on Diagram 26. Latch U1542
controls the remaining two increments to U1751 , the offset
current polarity selection , and five of the relay drivers on
Diagram 25. Latch U1551 ( Diagram 25 ) uses only three of
the
eight
possible
output lines
. Two of
these control the
output disconnect relay ; the third controls the Amplitude
Modulation function . Latch U1451 ( Diagram 25 ) controls
part of the Step Attenuator on Diagram 25 , two increments
of the DAC on Diagram 24 , and the Complement Relay
Drivers on Diagram 24. Latch U1341 ( Diagram 24 ) controls
the
Multiplier
DAC .
In operation , the CPU presents serial data at input pin 2
of U1642 ( Diagram 26 ) , furnishing the SHIFT CLOCK signal
to the clock input of all five latches simultaneously .
Following a serial shifting of the forty bits through the
register ,
loading
stops . The
CPU then
transfers
the data
from
the register
to the output lines
by pulling the
STROBE
A
signal high , then
low . This signal
is applied
to the latches
in parallel , so the transfer of data to the output lines is
simultaneous
.
圖
MULTIPLIER
Introduction
The Multiplier consists of two major circuits , the Level
Control and the AM Circuit . The Level Control receives the
selected function from the Sine Shaper circuits , amplifies it
to the desired value , and passes it on to the Output Amplifi
er . The Level Control performs the fine adjustments to the
output
signal amplitude
. The AM
Circuit
receives the
modu
lation signal
from the
front - panel
connector
,
processes it ,
then sums it with the Fine Amplitude Control Voltage .
Level Control
The Level Control consists of the following major circuits :
Input Differential Amplifier , Multiplier , Multiplier Current
Source , DAC , and Output Driver .
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Tektronix FG 5010 Specifications

General

Brand	Tektronix
Model	FG 5010
Category	Portable Generator
Language	English