Tektronix PG 508 User Manual

P aired pu lses are obtai ned by pus h i ng both t h e D EL AY
and UN D L Y b u ttons . An initial pulse now occurs at
external trigger time wit h t he secon d or paire d p ulse
delayed by t he selected delay time . The CO N
TRO L
ERRO R lig
h
t illuminates
if t h
e
d elay
is too
sh ort or lo ng for
α valid p ulse
train . Α custom d elay position is provi de d
on
t h e DE L AY switc
h .
To determine
t h
e
val ue
of
t heca p acitor
require d ,
multi p ly
t
h e
desired
d elay time i n seconds by 1 Χ
10 - Ζ . F or example, α 50 ms d elay time re q uires α 500 μ F
ca p acitor (50 ms ti m es 1 Χ 10 - Ζ ) . U se either a p ola r ized or
non-polarized capacitor wit h α rati n g of at least 6 V . If α
p olarize d cap acitor is u sed, observe t hep olarity mar k i ngs .
R emove t he i np ut boar d and connect t he capacitor as
sh ow n i n F ig . 1-2 .
Transition
T ime Selectio n
T h e leadi n g a nd traili ng times of t he p
ulses may be
varie d by usi n g t he
TRA N SITIO N
TIME co
n t r ol an d t he
LE ADI NG a nd TRAI L
I N
G va
r iable cont r ols . Select t he
desire d
tra n sition time range wit h t he TRA N SITIO N TIME
control a nd vary t h e lea d i ng and traili n g times in-
d epen d e n tly wit h t h e LE ADI N G an d TRAI L I N G co n trols .
Α custo m range position is also
provi d ed on t h e
TRA N SITIO N
TIME
co n trol . To select t he correct
capacitor (i n F arad s) for this ra n ge, multi p ly t he d esire d
transitio n ti m e (in seco nd s) measured from 10°/
ο
to 90°/
ο
poi n ts, by 4 .4
Χ
10 -3 . For exa
mp le, α d esired transitio n ti m e
of 50 ms
requires α ca p aciator of 220 μ F . Con n ect t he
capacitoras sh ow n i n Fig . 1-3 . U se αcapacitor wit h at least
α 10 V rating and observe p olarity r equirements .
Wh en t he tra n sitio
n times become la r ge com pared wit h
th
e duratio
n
or
perio d times an d t h e pu lse d oes n ot reac h
full
amplit
u d
e,
t
he CO N T R O L ERR O R lig h t will flas h
i n dicati ng imp ro p er control settings .
Output L evels
T h e
o
u t pu t amplitude and offset are selected b y
i n depen d en t p ulse L O W L EV E L and H IG HLEV E L con-
trols . U se t h e front pa n el voltage calibratio n mar k s fo r an
open circuit loa d an d divide t he values b y two
w h en t h e
P G 508 is o p erating
i n
to
α
50
Ω loa d . The O U TP U T
(VOLTS) co n trols are interloc ke d to pr eve n t setti ng t h e
H
IG
H L E VEL m ore negative t han t h e L O W LE V E L . . . It is
also im p ossible to set t h e co n trols for more t han about
20 Vp ea k to pea k out p u t am p lit ud e i n to an o p e
n circuit
o
r
10 V i n to 50
Ω .
P ulse amplitud e always e qu als t he pulse h ig h level
minus t he pu lse low level . Offset may be t he
h ig h level
or
t he low level,
w h
ic
h
ever is
used as t h e base li n e refere n ce
level . The flexi b ility of t h is met h o d is useful i n ce r tai n
a pp licatio ns suc h as logic
testing . E it h er t he h ig h or low
level
ca
n be varied wit h out disturbing t h e ot h er .
REV . Β , A PR . 197 8
Operati
ng
Instructio
n
s-PG 508
To determi n e t h e custom
ca p acito r
value m u lti p ly t he d esired d ur
atio n o r
delay time by 1 Χ 10 -2 . See text .
F ig . 1-3 . L ocatio n fo
r
tra n sitio
n
c
u
stom
timi ng capacito r .
T he p ulse h ig h an d low levels can be p reset . Pu sh the
PRESET button a nd ad ju st t h e HIGH LE V EL and the L O W
LE
VEL
poten tiometers wit
h
α screw
d river for t he d esired
outp
ut
levels
.
E xte rn al T riggering a nd Gati ng
Το change t h e' ΓΗΙ G/G ΑΤΕ IN i nput i mp edance
r
e
m
ove
t h e plug-i
n from t he mainframe . R emove t h e left si d e
cover . Set t he sli de switc h , locate d on t he I np ut boa r d and
labele d I npu t Impe dan ce, to eit h er t h e 50
Ω
o r the 1 ΜΩ
positio n . In t he 1 ΜΩ positio n t h e shun t capacita nce is
approximately 20 pF . Α stan d ar d oscilloscope p ro be can
be use d to ac qu i r e t he triggeri ng sig
n
al
from
t
he external
circuit r y . If α compe nsated probe is use d , calibrate t he
p r obe on t h e i npu t of α 1 MO 20 pF oscillosco pe first . Α
10 Χ p ro be allows t r iggeri n g d irectly from h ig h impeda nce
sources s uch as M OS d igital circuit r y wit h an effective
TRIG/GATE
L EVE
L
range
of + : .30
V .
For external gating select t he d esire d p erio d a
n
d
d u r atio n .
P
ress t he SY
N
C
GATE
pus
h
button
. Select t he
d esired trigger slo p e w it h t he+ or ~- S L O PE bu tto n . T he
OUTPUT now
co n sists
of
pu lses, d escri be d by t he f r o n t
p a n el controls, w h enever t h e TRIG/GATE IN inp u t ex-
cee ds t he TRIG/GATE L EVEL cont r ol setting .
To exter n ally t r igger t he P G 508, connect t he t r iggeri ng
sig n al to t h e TRIG/GATE IN co nnecto r . Select t
he
slo p
e
on w h ic h triggeri n g is d esi r e d wit h t
h
e + or
---
S
L O PE
b utton . P lace t h eP ERIOD switc h i n t h e ΕΧΤ T RIG O R
MAN
position . Now adjust the TRIG/GATE LEVELcontrol
for t h e d esired triggering level . 'T he output waveform
commences ab o u t 48 ns after t he triggering signal .

Tektronix PG 508 Specifications

General

Brand	Tektronix
Model	PG 508
Category	Pulse Generator
Language	English