Tektronix FG 504 User Manual

t h at t he STO P
FRE
Q is set
by t he STO P FRE Q d ial .
R elease t he STO P FRE Q button and press t h e T R IG S WP
butto n . N ote t h at t he fre q ue n cy no longer c
h
a
n ges . P ress
t he MAN
TR
IG
button and n ote t h at t he fre q uency
c
h anges o n ce . R eturn t heS WEEP D UR ATIO N k nobtot h e
O FF position .
P ress t he TR IG button in t he green section of
t he pan el
in . N ote t h at t
h
e OU
T
PU
T signal stops . Press t he MAN
button in t h e gree
n section i n and note t h at t h ere is o ne
com
p lete output cycle for eac h time t he MAN switc h is
p ressed . P ress t he GAT E button i n . Now
press t he MAN
button .
N
ote t
h
at
t he output waveform is continuous w h ile
t h
e MAN
butto n is p resse d . Press t h e FREE RUN button in
again for continuous out p ut .
T he out p ut frequency co n trols are outline d i n blue .
V ary t h e FRE Q UEN CY co
n
trol to see t he effect on
t he
output frequency .
T h
e
output fre quency MUL TI PL I ER
Kn ob selects t he fre q uency ran ge covere d by t
h
e
main
d ial . Switc h t he MUL TI PL I ER k nob to t
h
e
10 - Ζ range . As
t he sign al am p litu de slowly varies on
t h e oscilloscope,
pus h t he H O LD/ RUN butto n in a
n
d release
it several times
to see t h at t
h
e
oscillator stops at one point on t he
waveformand t h en begi ns at t he same poi n t w h en t he
button is released .
T h is completes
t he first time operation of t he instru-
ment .
R isetime and F alltime
If t h e out p ut pulse from t he F G 504 is use d to measure
t h e rise or falltime of α d evice, consider
t he risetime
ch aracteristics of
t h
e
associated eq ui p me n t use d . If t he
risetime of t h e d evice un d er testis at least ten times longer
t h an t he combi n ed risetimes of t he F G 504 plus t
h
e
mo n itoring oscilloscope an d associated
cables, t h e error
i n tro d uced
will not excee d 1 ο / ο . T h is error can generally be
ig n ored . Wh en t he rise or falltime of t he test device is less
t h an ten times as long as t h e combine d risetimes of t he
testing system, t he actual risetime of t
h
e system
must be
determine d . T h is is fou
nd from t h e risetime of eac h
com
p
o
n
e
n t ma king
up
t he system . T h e total risetime
e q uals t he square root of t he sum of t he s q uares of t he
i n divi d ual risetimes, or :
REV ΜΑΥ 1981
R, _

( R
ι
) Ζ +
~
R
z ) Ζ
+ . . .
O n ce t he risetime of t he system is k now n , t h e risetime
of t he d evice under test ca n be foun d by using t he
preceding met h od .
T h e p h ysical and electrical ch aracteristics of t h e pulse
transmitting cable determine t he c h aracteristic im-
Operati ng I n st
r
uctio
n s- F
G
504
(S
N Β 040000 & UP)
ped a n ce, velocity of pro p agation, and amou
n t
of
signal
loss . Signal loss is
relate d
to
fre q ue n cy . Α fewfeet of cable
can attenuate h ig h frequency informatio n i n α fast-rise
pulse . It is t h erefore im p orta n t to k eep t h ese cables as
s h ort as practical
.
Wh e n signal compariso
n
measurements or
time
d ifference determi
n ations are made, t h e two signals from
t
h
e test
d evice s h ould travel t h roug h coaxial cables with
identical loss and time delay ch aracteristics .
Impedance M atc h ing
As α pulse travels d own α transmissio n li n e, eac h time it
en counters α mismatc h (or an im peda
n
ce
d iffere n t t h an
t h at of t
h
e
transmission li n e), α reflection is generated an d
sent bac
k along t he li ne to t he source . T he amplitu d e an d
p olarity of t he reflectio ns are determine d by t he im-
pe d ance mismatc h en countere d . If t he im p eda n ce mis-
matc h is α h ig her value t
h
an
t h
e
line imped an ce, t he
reflectio
n
will be of
t h e same polarity as t he a p plie d sig n al .
If it is α lower value t h a nthe line im p edance, t he reflectio n
will be of o pp osite polarity .
If t he reflected sign al returns before t he pulse is en d ed ,
it adds to or subtracts from t
h
e am
p litu d
e of
t he pu lse . T h is
distorts t h e pulse sh apeand am
p litu d
e .
If t he F G 504 is d riving α
h
ig h im
p
ed a n ce suc
h
as
t h
e
1
ΜΩ i n put impe d ance (paralleled by α stated capac-
itance) of t hevertical i np uttoanoscilloscope, connectt he
tra n smission line to α 50 Ω atte n uator, 50 Ω terminatio n ,
an d t h en t he oscillosco pe i np ut . T h e attenuator isolates
t he input ca p acitance of
t h
e device,
an
d
t h
e
F
G
504 is
prop
erly terminated .
F ree R unningOutput
Select t he d esired waveform (s q uare,
triangle,
or si
n
e)
by pus hing t he a pp ropriate button mar ked wit h
SQ
UA REW A VE, TR IA N GL E , or SI NEW A VE symbols .
P us h th e FREE RUN butto n . M a k e certain t he S WEEP
D UR
ATIO N switc h
is
in t he O FF p osition . Select t he
d esired fre q ue n cy wit h th e MUL TI PL I ER a n d FRE-
Q UEN CY H z (STA R T) d ials . T he FRE Q UEN CY VERN I ER
control p ermits fi ne freque n cy ad j ustme n ts . Connect t he
load to
t h
e
O
U
T
PU
T terminal . M ake certain t he H O L D
butto n is out . Set t he ATT ENU ATO R co n trol for t he
desired p ea k -to-pea k output amplitu d e . U se t he V A R
k nob to
vary t
he am
p
litu de between t h e steps
.
T he waveforms with out offset center around 0 V . To
offset t he waveforms, pull an d rotate t he O FF SET control
for t h e d esire d offset . If α square-wave out p ut is selected,
ad j ust t he R IS E an d F A LL TI ME co n trol for t he desire d
values .
T h
e
V
A
R
k nob varies t h ese times between
t
he
E nglis h 2- 5

Tektronix FG 504 Specifications

General

Brand	Tektronix
Model	FG 504
Category	Inverter
Language	English