HP 5383A

4-1 . I N T R OD U CTIO N
42 .

Th
e
t h eo r y of ope r atio n is w r itten p r ima r i l y at α f un ctional bloc k level . Some d etaile d
ci r
c
u it t h
eo
ry
is p
r ovi ded as an ai d to t r ou bles h ooti ng w h en ci r cuit com p lexity r equ i r es it . In
a dd itio n ,
br
ief ci r cu it expla n atio n s a r e give n fo r two un i que integ r ate d ci r cuit p ac k ages
:
t h
e
Va r ia b le Time Base Co un te r a nd t he H ex M ulti p lexe d Co un te r s .
4-3 . FUN CTIO NA L D E SC
R
IPTIO
N
4-4
.

T h
e 5383 Α
is α d i r ect f r
equ
ency co un ti ng i n st ru me n t w h ic h comp u tes i npu t fre quen cy "f"
by cou n ti n g t h e nu m b e r of cycles " η " t hat occ ur s dur i ng an i n te rn ally gene r ate d time b ase
i n te rval "t" . T h is f r e quen cy meas ur ement
f
un ctio n is d escri bed sim p ly by t he followi ng
equ atio n :
η =fxt
η = n um be r of cycles
f = f r equ e n cy of i npu t sig n al
t = inte rn ally gene r ate d time base interval
O
n
ce calculate
d , " η " d
ata
mu
st
be sam p le d a nd
co
rr ectly t r a nsfe r re d to t he
9- d igit cou nte r d is p lay .
4-5 .

I NPU T CI R CU IT
46 .

( R efe r to F ig ur e 4-1 and to sc hematic .) Sig n al "f" is a p plie d to t h e i npu t ci r c u its con sisting
of A2S2, A1Q15, a nd A1Q14 . In pu t switc h S2 r o u tes t he sig n al to eit
h
er t h e 1 ΜΩ
Χ
1, Χ 10 p at h , o r
t he t h e 50 Ω pat h . Q14 and Q15 b iases t h ese sig n al pat h s, allowi n g t he Bala nced I nput Amplifie
r
to
accept eit he r t he 50 Ω o r t h e 1 ΜΩ sig n al ( r efe
r
to t
h
e sc h ematic fo
r d
etaile d b
iasi ng i n
fo
r matio n
a
nd corresponding
signal p at h selectio n ) . A2S2 ca n also select α 1 ΜΩ Χ 10 atte nu ato r consisti ng of
α 1 :10 voltage divi de r n etwo rk .
T
h e
50 Ω
sig n al p at h consists of :
The 1 ΜΩ Χ 1, Χ 10 p at h consists of :
SE CTIO N I V
T H
EO
R Y
O
F
O
P E R
ATIO
N
α .

0 .1 amp fuse Al F 1 (3 .5 V r msmaxim u m in p ut) .
M od el 5383 Α
T
h
eo
r y
of Ope
r atio n
b .

Clampi ngand limiti ng d io d es (A1CR 12 and CR 13 ; a nd A1C
R
8
t hru
C
R 11) whic h limit t h
e
i npu t to
1 volt pea k -to-pea k .
α .

FE T's A1Q17, Q18, a nd E mitte r followe r A1Q16 .
b .

Α switc h able low p ass filte r consisti ng of A1 R 55 a nd C44
.
'Boa
rd
-mo
un
te
d switc h A1S2
("F I L T ER") switc h es t h is filte r i n o r o u t .