Tektronix FG 5010 User Manual

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In addition , the outputs of U1201B switch differential pair
Q1114
-
Q1113
,
causing
the
CLOXON
signal
to
Loop 2 to be
low , and the
BURST
ON
signal ( rear
interface option ) to be
high .
Gating Mode . In
this mode ,
FREEGATE
is high
. Thus ,
U1211A is
disabled ,
and no
trigger
pulse can be
generated
.
The TRIG /
GATE signal
goes low at
the
outset
, so
pin 14 of
U1211B goes high to reset U1201B . ( U1201A stays reset
because
BURST
is still high . )
The positive level
from pin 14
of
U1201B pulls
U1211C
,
pin 6 ,
low ,
causing the
Clamp
Enable
Switch to
start the
main
loop
running
.
The high BURST signal from Q1201 holds the reset in
put , pin 4 of U1201A high , so the D input , pin 10 of U1201B
is high . The loop continues to run while the gate signal
moves negative to release the reset state of U1201B . When
this occurs , the next positive edge at pin 11 sets the flip
flop , pin 14 moves low , enabling U1211C to switch . This
occurs at the next negative transition of the applied HFSQ
signal at pin 10 , which corresponds to the negative extreme
of the triangle wave in the main loop . The Clamp Enable
Switch
immediately
shuts
off the loop ,
and the
triangle wave
signal operates for only the gate length , as a result . Howev
er , since triangles are always produced in integral numbers
of cycles , the loop will stop at the same point on the same
slope as the
start ,
following
the
gate ending .
Burst Mode . In this mode , the FREEGATE line is low ,
which allows the trigger pulse to be generated . The BURST
line is also low , so U1201A is not held reset as before . Thus ,
the first trigger sets U1201A , and resets U1201B . This
places a low level at pin 10 of U1201B , and the high level
from U1201B pin 14 triggers the Clamp Enable Switch to
start
the
main
loop
running .
As long as U1201A remains set , the D input of U1201B
remains low . Thus , the clock signals applied to pin 11 won't
alter the flip - flop state . When the burst is to end , the
END OF
BURST
signal moves low , and
the
positive edge
at pin 6 of U1201A clocks the flip - flop to the reset condition ,
and pin 10 of
U1201B moves high . At the
next
positive edge
at pin 11 of
U1201B
, the flip -
flop sets , pin 14
goes low , and
when pin 10 of U1211C next goes low , the main loop is
stopped
to
end
the burst .
Theory of
Operation -
FG 5010
Clamp
Enable
Switch
This circuit
consists
of
Q1224 and
Q1223 , and also
Q1222 and
Q1221 , which
are not
involved directly
in
the
clamp switching . Transistors Q1224 and Q1223 form a dif
ferential pair that steers the current for the Phase Clamp
circuit , and thus control the circuit operation . The current
that flows through R1224 and R1225 is sufficient to over
come
the
21
generator and
to pull the
node at the
cathode
of CR1324 up to 1.4 V , when CR1322 and CR1321 clamp
the circuit . This permits the loop to free - run . If the differen
tial pair switches , the cathode of CR1324 is pulled down to
the point where the charging current is taken by the 21 ,
UP
current source , stopping the loop .
UP
The collector of Q1223 controls transistor Q1222 , which
in turn control Q1221 , which is the path for the Schmitt
Defeat control from latch U1301 . The drain of Q1221 con
trols transistor Q1233 ( Diagram 12 ) . When the loop is run
ning
,
passage of
the
signal is
blocked , so
that the
circuit
does not
affect the trip
point when
gating ,
triggering
,
or
burst modes are selected .
Square
Selector
Transistors Q1022 and Q1021 are a level translator that
converts ECL levels to TTL levels for use by the Loop 2
circuits . The
HFSQ and HFSQ
signals are
differentially
ap
plied to the circuit . The output is taken from the collector of
Q1022 .
The HFSQ signal is also sent to U1011A , the other input
of which is controlled by Q1121 . The HI RANGE signal is
applied to the base of Q1121 . If the signal is high , Q1121
conducts , cutting off Q1122 and enabling the signal at pin 4
of U1011A to pass through to pin 13 of U1011C . Since
Q1122 is cut off , the LOW FREQ SQWV signal cannot pass
through U1011B , and the low at the output of U1011B en
ables
U1011C
to
complete
the
path for the
fast
squarewave
signal . Two complementary outputs are produced , SE
LECTED SQWV and SELECTED SQWV . Both are fed off
the board for use in other circuits , and the SELECTED
SQWV
is
used to
control U1201 pin 11 .
4-21

Tektronix FG 5010 Specifications

General

Brand	Tektronix
Model	FG 5010
Category	Portable Generator
Language	English