Krohn-Hite 3550 Assembly Instructions

SOLID STATE
VARIABLE FILT ER
MODEL 3550
SERIAL NO. __
OPER AT I G AND AINT NANCE
MA NUAL
KRD
- ITE CD R PCRAT ID
Avon Industrial Park/Bodwell St., Avon, Massachusetts 02322
CD 1975 KROHN- HITE CORPORATION

Con t en
ts
CONTENTS
Se c ti on
1
GE NE RAL D ESCRI PT IO N . . . . . . . . .
2 O P E R A T ING I
STRUCTIONS . . • . . ..
3 IN
COMING AC CEPTANCE AND INSPEC T IO N
4
CIRCU IT DES CRIPT IO N . . . • .
5
MAINTEN A NC E ....•..
6 CA L
IB R AT ION AN D ADJ US T M E N T
ILLUSTRATIONS
F igure
1-1 M o de l 35 50 M u lt if u nc ti o n F i l te r .
2-1 F r ont and Rea r Pa ne ls .
2-2 Pas s Ban d C ha r a c te r i s t ic s .
2- 3 Normalized At tenuati on C ha r a te r is tic s
2- 4 Squa re Wa ve Response .. ' . ....
2- 5 P ha s e Shif t . . . . • •e •
4 -] loc k Diagram . . • • . . . . .'
4 - 2 R e s po ns e
of Q ua d r a t ic A mplifie r s •
5 -1
Trim s and A dj u st m e nts . ..
Appendi x
S c h e m a
ti • Layout a nd P a r ts L is t
TABLES
Table
3 - ] Acc e ptan c e Che ck out P r
oc ed u r
5- ]
Te s t P oint v s S igna l Volt ag e
6- 1
Ca l ib r ati on P ro c ed u r e . . . .
P a g e
I
4
I I
15
20
24
P a g e
ii
5
8
8
8
9
16
17
21
~
E nd
Pa g e
12
22
26

F i lt er, 3 55 0
. 1 . 10 ,100
.IK
INPUT
I<ROH -HITE
mo de. 3550 filter
F ig u r e 1-1, Model 3550
Multifunction Filter
ii

Se ctio n I - General D escripti on
SECTION 1
GENERAL DESCRIPTION
1.1 INTRODUCTION
T h e K r oh n - Hi te Mo de l 3550 , shown i n F igu re 1- 1, is a mu lti func tion filte r
that ope r a te s in a h igh -pa ss , lo w -pass , band -pass , or band -reject mode .
The c ut off frequencie s a r e independentl y a dj u s ta bl e bet ween 2 H z an d 2 0 0kHz .
A n
optional rack -m ounting kit (P a r t No . RK - 38) is a vailabl e f r om Kr oh n -H ite
(or install ing th e Model 3550 in a standard 19" r a c k spacing .
1.2 ELECTRICAL SPECIFICATIONS
Function
L ow -pas s , h igh - pa s s , b an d -p a s s , band- reject.
Cutoff F requenc y Range
BAND
M UL T IP L IE R F
RE QUE NC Y (Hz )
I O. 1 2 - 20
2 I 20 - 200
3 10 20 0
-200 0
4
5 l Oa
lK
2,
000 -20 , 000
20, 000 - 200, 000 \
F requenc y Can1 ,01
L ow - pa s s and high-pass functions ea ch have one decade dial and a 5- position multi -
p
li e r s wi tch , e ff e c t ivel y a 30 i nch lo ng scale fo r the 5 fr eq uen cy band s .
Cutoff Frequency Cal ibrc tion Accu 'a cy
±50/0 bands 1 t h r u 4, ±lO% band 5 with RESPONS E s wi tch in MA X F LA T (B ut t e r wo r th)
pos i tio n ; l e s s a c c u r a te in L OW 0 p ositi on . Re la tiv e to m id- ba nd l ev el, the f il t er
output i s do wn 3d B a t cu t o ff in MA X F LAT po sition a nd app roximate l y .1 2. d B in
L OW 0 pos i
ti o n.
Bandwidth
Lo w -Pass Mode : F ro m a pproximate ly 0 .2 Hz to c u to ff setting b et we e n 2. °H z to
200 kHz ,

Filter , 3550
Hig h -Pass Mod e : F r o m cu toff s e tt ing of 2. 0 Hz to 2 00 k Hz , to ap p ro x ima t el y
3 MH
z.
Ban d-Pass: Bot h cut offs a djustabl e fro m 2 . 0 Hz t o 2 00 k Hz , F o r m in im um ba nd -
wid t h
(Butt e rwo rth response ) both c ut o ff fr equencies a r e s e t to c o in c id e . Th is
p r
oduce s an inse rt i on loss of 6 dB , with the 3dB po int s a t 0 .8 an d] . 25 time s the
mid-ban d frequ e nc y.
Ban d-Reject: Bot h cutoff f r e qu e nci es adj us ta b le fr om 2. 0 Hz to 20 0 k Hz . Lower
pass band to ap p r o ximatel y 0. 2 Hz, upper passband to app r o ximatel y 3 MHz . A
sh a rp n ul l can be ob ta ined b y s etting th e Hig h Pa ss s e ct ion to about t wice the null
fr eq ue n c y, and the L ow P a s s s e ct i on to half the null fr e quen cy, and a l te r n at el y a d-
justin g both d i al s fo r minim um r e s pon s e .
Response Charocteristi cs
Choice of 4 pol e Butt e rwo r th (Maxi mally fi a t res pon s e) fo r fr e que nc y d om a in op e r a -
tion and L ow Q (da m ped res p on se) f or tr a n s i ent - fr e e ti m e dom ai n operati on,
selected by mean!') of a switch on the rear pa ne l.
Attenuation Slope
Nominal 24 dB per o ct av e In all rn od e s of o pe r a ti on .
Pa$S Band Gain
Zero db +1 db in pass band.
Maxi mum Attenuat ian
Great er than 60 dB
Input Character; stic 5
Max Volta g e : ±7V peak to 2 MHz.
Max DC Component: ±lOOV.
Input Irnped anc e : 10 Megohms in parallel wit h 50 pi.
Output Characteri 51iC5
Max Volta ge : ±7V peak to 2 MHz.
Ma x Current: ± 15 rna peak.
Internal Imp ed an c e : 50 ohms.
Hum lind Hoi se
Less than 200 uv , except 400 uv in "BAN D RE JECT" rn od e ,
2

Section 1 - General De sc ript ion
Output DC Le ve l Stobi I ity
± l m y / oC t ± l rnv Zhr . Som e what g r e ater in BR m ode .
Front Panel Control s
High Pass Sectio n : Hz d ia l a nd m ultip l i e r sw it c h.
Low Pass Sectio n : Hz d i al and multip lie r s w it c h .
Function Switch : LP, HP , BP, E R.
P owe r
ON Switch
Reor Ponel Control s
Re s p on s e Switc h : M AX FLAT , LOW Q.
Gr o un d Switch : C HASSIS, FLO A TI NG .
DC L e v e l: P
ot entio m et er.
L in e S wi t ch : 115V /230V.
Terminals
F ro nt an d r e ar pa n el s , one E NC con ne cto r fo r IN P U T, one for OU TP UT. AC power
r e c ept a cl e w it h d et acha b l e l in e co rd . On e r ea r ter mi na l for ch a ssi s g r ou n di ng .
POWIIT Henuirernants
105-125 or 210-250 volts, sin gle phase, 50-400 Hz, 10 watts.
Operating Temperature Range
occ to 50aC .
Dimensions and Weights
Mo de l
Ov er a ll D im e n s io n s We i
ht
Widt h
Height
Dept h Ne t S
hip p ing
355 0 8 1/ 2" 3 1/ 2" 13 " 9
Ib/4kg
14 Ib / 7kg
3

F i lt e r , 3550
SECTION 2
OPE RA TI NG INSI CIIONS
2.1 INITIAL SETUP
T he fi lt e r is ad jus te d and checked ca r ef ul l y in our test department to insure t ha t it
mee t s al l specifications . It is then age d and teste d aga in bef o re shipmen t. The
filter is shi pped complete and afte r un pa ck in g is read y for use.
Th e M od el 3550 s ho ul d be unpacked ca r ef ul l y and in s pe ct ed f or damag e tha t ma y
ha
ve oc c u rr ed in s hipping . Check all controls for freedom of ope ration .
T
he Filte r may be op er at ed f rom an A C powe r s ou rc e of e ithe r 10 5- 125 vo lt s ,
50 - 4 00 H z ,
or 2 10 - 250 vo lt s , 50 - 4 00 H z . A I1 5 / 2 30 V LI NE wi t c h, l oc at ed on th e
r e
ar pa n el , s e le ct s t he filt er' s mode of ope r at io n, Wh en t he AC line i s 115 V, m o ve
t he LIN E s wit c h to the I 15V po si tio n . In t hi s mod e , a 1/ 8 ampe r e 5 10- b lo fu s e ITlUS t
b e u s e d . Whe n th e
fi lte r is to be op e r a ted f rom 230 V AC , m ov e t he L I NE s wi tc h to
t
he 2 30V po sit io n, and r e pla c e t he fu s e w it h a 1/ 16 am pe r e slo -bl o typ e .
2.2 CONTROLS AND TERMINALS (figure 2-2)
2.2.1 Fro" I Ponel
T he fun c tio n s witch in the top center of th e front panel selects on e of fou r fi ltering
f un ct ion s : L ow P a s s (L P ), Hig h P a s s (H P ), Band P as s (B P), o r B a nd R e je c t (BR ).
4

g
FRONT VIEW REAR VIEW
FIGURE
2-2. FRONT AND REAR PANE LS
CD POWER SWITCH (ON IO FF )
® INDICATOR LI GHT
@INPUT CONNECTOR (BNC TYPE)
®OUTPUT CONNECTOR (BNC TYPE)
®MULTIPLIER SWITCH (HIGH PASS)
®MULTIP LIER SW IT CH (LOW PASS)
oFREQUENCY DIAL (L OW CUTOFF)
®FREQUENCY DIA L (HIGH CUTOFF)
® 115 / 23 0V LI NE SWITCH
® OUTP UT CONNECTOR (BNC TY PE)
@ INPUT CONN ECTOR (BNC TYPE)
@
I/ BA SLO- BLO !lT V
12 FUSE 1/ 16A SLO-BLO 23 4V
@POWER RECEPTACLE
@CHASSIS GROUND CONNECTOR (BINDING POST)
@GROUND SWITCH (FLOATING I CHASSIS)
@ RESPONSE SWITCH (MAX FLAT I LOW 0)
@ DC LEVEL POTENTIOMETER
@ FUNCTION SWITCH (LP, HP, BPt BR)
F igur e 2 - 2. F ro nt and Rea r Pan e ls
:.n
(1)
('l
,...
... .
o
...
N
o
v
l't>
-t
PJ
...
... .
::J
()Q
5'
til
...
....
c
('l
...
....
o
::l
t1l
VI

F ilter , 355 0
The cuto ff frequencies are se t by d ia l s and rn ul t i pl ie r s w it c he s, o ne fUI' the Hig h
P a s s a nd o
ne fo r the LLl\\ Pass s e c io n s.
T he p owe r O N sw i tch and indicato r li g ht in the l owe r cen ter comp lete th e fr on t pane l
c on t r o l s .
B NC C
on n ec tors fo r INPUT and OUTPUT a re loc at ed in I he l ow e r co rners .
2.2.2 Rear Panel
The R ESP O SE s wi tc h provides cho ice be twee n MAX FL AT and LO\ .\,' 0 r e sp on s e of
t he Model 3 5 50 . T he G R OU. ' D sw it c h, r e ce s s ed in the r e ar panel t o p r e v en t in -
ad ver tent oper ati on , conn ec ts the ch ass is to ci rcuit g rou nd in t ne CHAS SIS pos it ion
and disc onne cts them in F LOA TI G . T he DC L E V EL mu l ti tu r n s c r ewd ri ve r - ad -
ju
stabl e potentiomet er p ermits se ttin g of th e ou tpu t DC l ev el. T he LINE s wi tc h
s
elect s 115 V r 230 V A C ope ra t ion .
The IN P U T a nd OUT P UT BNC co nne c to r s a gain oc cup y t he c o r ne r s a nd th e CHASSI S
bingin g po st p rovides m eans for groundin g the chassis .
A
fuse holder l ab e l e d wit h th e r equ ir ed fus e ratin g , is a lso mount ed on the l' a r
pan e l.
2.3 OPERATING PROCEDURE
2.3.1 Conn ect t he Mod el 35 50 to th e power line.
2.3.2 Ma ke c onne ct i on s t o the INP UT and O UT P U T.
2.3.3 Set the fun c ti on s wi tch to th e d e s i r e d m od e a nd th e High P a s s and Low Pa s s
section cont ro l s to the r e qui r ed fr e q uen cy ran ge s.
2.3.4 T u r n ON pu \'. ,'er.
NOTE
If the in put s ig na l exceeds the m ax im um
sp e c i fied lev el s ( 7v pe a k, ± IOO vdc ) or if
the o ut pu t c u r r e nt ex c ee d s ±15m A pea
cl ipp ing w ill oc cu r .
2.4 SPECIAL FUNCTIONS
2.4.1 Narrow Bon dposs
Nar r o we s t pass ban d in the ba nd - pa s s mod e is o bt a ined by s e tt in g bot h c uto ff fre-
quen ci e s eq u al a s s ho wn in figu r e 2-2, cu r ve C. T he r e s ul t ing in s e r tion los s is
6

Section 2 - Ope r at ing Instructions
6 d B, (a t band ce n te r) , and the 3 dB points ar e at ab ou t 0 .8 and 1. 25 times m id -
band
frequenc y .
2.4.2 Null
A s ha r p null can be obtained in t he Band Rej e ct m ode by setting the L ow Pass
section to ha lf the n ull f r e que n cy and th e Hi gh Pa s s sec ti on t o t wic e the n ul l fre-
quenc y an d a lt e r natel y adj us t ing bo th di al s to m in im i ze the ou tp u t. Fi gu r e 2 - 2,
Cur ve D.
2.4.3 Maxi mom Flot vs, Low Q Respon ses
In the MA X FLA T po s it ion of this rear - pa nel switch the fil te r res p on s e i s a fo u rt h
o r de t: B utte
rwo r th f unct ion:
VI + S8
VI + S8
G=
gain
f
S -- -
fa
f = fr eq ue nc y
fa = c ut o
ff fr e quency setting
Th is r s po ns e is plotte d as the s o li d cu r v es in F igur 2-2, cur ve s A a nd B ,
a.nd norma lize d on ~ larg e r s ca le as i n F i g u r e 2-3. It h ug s th e O- d B
li
ne v er y close ly wi.th no r i ppl s a Irn os t to the cut off freq u ency , a nd the n
k.
ee ps cl os e to th e 24d B /oct a ve a s sy m p to te , d ep a r ti ng I dB fr om these
l irie s at f /fo= 0. 8 an d 1. 25 r e spect i vely.
The li m it a tion s of t hi s ty pe of f il t e r a r e appare nt in F igu r e 2-4(al w hich shows the
s te p- f un ct ion r e s ponse of a fou rt h o r d er But te r w or th l ow pa s s . Fo r a pp li c at i ons
wher e thi s eleve n per c ent ove r s hoot cann ot be t ol e rated , the Mo d el 3 55 0 p r ov id e s
t
he L O W 0 po s i ti on of th e R ES PO NS E s wit ch . In this m od e the sh a rpness of th e r.u t -
o
ff is r ed uc ed ju s t en ou gh t o eli mi na te the s te p - f un c tio n o ve r sho ot (s e e Fi g ur e 2-4(b)}.
T he f r e qu e nc y r e s pon s e of t he L O W Q mod e is s hown by th e d ot t ed c ur v es in
Fig u r e 2 - 2 (c u r-v e s A a nd B). Obv iousl y, the cutoff i sm uch Les s sh a r p, t he a tt en ua -
ti on at t he c or ne r is a pprox imat ely 12 dB and the I dB po in ts ar e a t 0.2 and 5 ti m e s
th e cutoff freq u e nc y.
T h i s reductio n of cu to ff sharpn es s ha s n o r e al m ean ing fo r a high - pa s s filter but
wa s i n
cl u de d in th e Model 3 550 hig h pa s s sect ion to pro vid e sy m metrical band pa s s
and band reject cu rv e s w hen the LO W Q mod e is us e d .
7

F il t e r , 3 5 50
A - LOW PASS B - HIGH PASS
..... "
<,
1\
1\\
~~
\ \
\ I \
I \ I \
I I
db
db o
o
-2 0
-20
-40
-40
-6 0 -60
20Hz 200KHz 2MHz
C-BAND PASS
100 IK 10K lOOK 1M
Hz
I
.'
/'"
'-1
/ \
~ \
/ \ 1\
I I / \ I \
I ' I \ , \
I I I \ I
db
db o
o
-2 0
-20
-40
-40
-60
-60
.I 10 .1
:
li/ '" {./
III,
~ :
I
I I I I
I I I I
I I I I
20Hz
20 0KHz 2MHz
0- BAND REJECT
-,
\ ( /
I ' ~
V,
\
I \ I
1 \ I I
I I
10 100 IK 10K lOOK 1M
Hz
Figure 2 -2. Pass Band Cha r a ct e r i s ti c s
o
2
---
....
1\\
-, \\
'\
\
, \
\ \
\
\ ,\
IHP ot< IGli PASS OJlOtT FREC'JENCY
'.\
fLP'LOW PASS CUTOFF fREQUENCY
\\
I II \
I II .\
(a)
- 6
_ - 12
'"
':.
~ - 18
'"
Il:
~ -24
-'
i::
- 3 0
- 42 I 3 4 5 6 7
891 2 ~
4 56 18 10 (b )
-O R !liE
fLP f
Fi g ur e 2- 3.
No r m a l i z e d A tt e nua tion Cha r a c te ri s ti c s F ig
ur e 2-4. Sq ua r e Wa ve Re s pons e
8

Sect ion 2 - O pera ting Instructions
2.4.4 P hase Response
T he ph a s e s h ift in eac h sec ti o n of the fi lte r is s ho wn in F ig ur e 2- 5. In t he dr a win g
a po s i t
iv e angle m ea ns p hase lead , i. e . I the out p ut vo lt a ge lea d s in pu t vo ltag e . T he
solid cu r ve is fo r MA X FLAT mo de , and t he do tt ed c ur ve f or LO W Q m ode .
Wh e n
th e M ode l 35 50 is used f or ban dpa s s , bo th sec tion s ar e c asc a de d (s e e Sec tio n 4 )
a
nd ph as e sh ift s a dd a lge b raicall y . No te th at at pa s s ba nd cente r f r eq u en c y (f = fHf
L)
the ph a s e s hif t i s ze r o. A n exam ple of the com pu t at ion of pha se s hi ft i n the ba nd pas s
mo de follo ws :
Giv en : P a s s ban d 100 Hz to 500 Hz (i. e . Hi h Pa ss s e c ti on se t to 100 Hz a nd the
Low Pass sectio n se t to 500 Hz . . )
F ind : P ha s e
shift a t 200 Hz MA X F LA T res pon s e
20 0
Hz
1.
High pass
r el a tiv e fr e que n
cy = =2. 0
100 Hz
20 0 Hz
2. L ow P a ss r el a tive freq uen c y = = 0 . 4
500
Hz
+ 360
t:::---
.........
--
.... -
r-,
<,
f"'-.,. r-..
<,
....
' ...
f'\
I' , :\
~~
1\ '
\: ' ,
"""
.... ,
<,
............ "
............
.......
I--
. ....
.....
. ~
-r-.
I-
-
o
-60
.3 0 0
lJ} lJ}
w w
W W
IX:
IX:
~ + 2 4 0 - 120
~
o o
w w
<J)
<l: +18 0 - 180 <;J,
I I
a..
n,
lJ}
lJ}
lJ}
lJ}
-240 rt
tt. -+ 120
I
~
£1
...J
I
-+ 60
-~oo
o -360
1 2 .4 .5 .6 .7 .8 .9 I 2 J .. 5 6 7 9 910
RELAT IVE FREQUENCY
F igu r e 2 - 5. P ha se Shi ft
9

Fi l t e r , 3S50
- 3. R e fe
rr ing to F ig u r e 2 - 5 :
Hi g h pa s 5 ph a s e s h ift
Low a s s ha se s hift
4 . R e s ul t a n t ph a s e s h i ft =2 0 0
In the band r ej e ct mod e , the
Hi gh Pa s s and L ow P a s t> se c t ion s a rc c on nec ted in
a
ra lle l (se e Sec i n 4) . T h
pha s e s h if is t he n d et e r m in ed ve c t o r a .l y add i ng th e
c on t r ib
ut ion s o f bo th f ilt e r s . An e xa
mp l e io ll o w s :
G iv
en : Re je ct B and 1 00 Hz to SOO Hz (L ow Pas s s e c- lion set t 10 0 Hz a nd
ig h P a s s secti on to SOO Hz ).
F i nd :
Attenuat ion a nd p ha s e s hift a t l Oa Hz .
1. H
igh pas s re l ati ve fr eq u en cy 20 0 Hz = 0 . 4.
SOD Hz
L 1 " 2 00 Hz -= 2
2.
ow pass r c atrv e 1r e quenc y 100 Hz .
3 . R e fe r r ing to F'ig ur e 2- 3:
h I ' d f SOOHz "7 S 3 2, d b
H'
pa s s no r rria rze r equ en cy 200A z - w . =19
. f
lOOH ,.; 2. 0 2. 4dl
Low pa s s n o r rna Ii z e d r eq ue nc y 10 0H z = . = )
4. F or filter vol t a g e input £ :
Hi g h
pa s s s ect io n ut pu t
= . 02 S Et30 00 =,01 2, 2E - jo . 02 J6 £
Lo w pas s s e ction o utput
= . 0 62 5£ 1- 2 80
0 =. 0 10 8 £ + jO. 0 6 I S £
Sum . 0233 £ + jo, 03 9 9 £ = 0 . 04 62 £ IS9. 70
T he a tt e n ua t io n is 2 6 . 7 dB a n pha s e hi ft
1 11

Se ction 3 - In co m ing Ac cep tanc e a nd Ins pe ct ion
SECT IO N 3
INCOMING ACCEPTA CE AND INSPECTION
3.1 INTRODUCTION
T he fo ll owing pro ced u r e s h o ul d be u sed to veri fy the Filter operati on within specifi-
c ation s. The se c he ck s m a y be u s ed for in c o ming in s pection and periodic specifica-
ti on chec ks . Test s must be m ad e wit h al l co v ers in place. If the instrument is not
ope r a t ing w it hin sp e ci fic a ti on s ref er to Se cti on 5 and 6 b efore attempting any detailed
mai n te na nc e. Before te s ting, follow t he i ni ti al setup and operating procedures given
in Se ct i on 2 .
3.2 TEST EQUIPMENT REQUI RED
The followir , ,.,, ,( :st e qu.i pr n e nt is required to perform t he se tests:
a. RC Oscillator, with frequency rang e 0.0 1 H~ to 1 MH z, frequency
accuracy +0.5% to 100 k Hz , frequency r es po ns e better than +0 . as dB and distortion
less than O. 02~t, K'r ohn Hi t e Model 41QUA or equival ent. - .v
b. Oscilloscop e, with DC to 50 MHz bandwidth, vertical input sensitivity of
I mv/em, 'I'r-k t ro n ix type 544, with type lAS plug-in, or equivalent.
c. AC Vo ltri i. -L cr , capable of rri o a su r i ng 100 microvolts to 10 volts RMS,
Ba llantine Model 314A or equivalent.
d. DC Vo lt r-ic-t c-r , capable of nl eii~uri :-J~ : 1 millivolt to 20 volts, Fluke
Modd ~ ; O O O A or equivalent.
e. Variable auto-transformer for a dju st i nc line voltage.
3.3 TEST PROCEDURE AND CONDITIONS
Table 3 -1 g ive s the c on di ti ons a nd se tup fo r testi ng the v arious filter character-
i stics. U nl es s o th e r w i s e sp e ci fi ed in the ta bl e, th e RE SP O NS E s w it c h i s in the
MAX F L AT po s it ion, an d the outp ut l oa d i s g r ea te r than 1000 oh m s. In the table,
volta g es a r e r m s u nl e s s othe r w ise s pec ified .
11

--
--
--
----
Filt e r , 3 55 0
Ta bl e 3 - J • Accept anc e C he ck out P r oc edu r e
F
unc- BP Se cti on
LP Se c tion
Inpu t
Te st
tio n Cuto
ff
Cuto ff
F r e qu enc y Set Am p litud e
I .
"Low
L P ZO O x 1000 60
kHz
I V at Out pu t
P a s s
Ope ration
Me a s u r e o sc
vo lt ag e a t f il te r inpu t.
L i mit s ar e 0. 9 to I. I vo lt s . F oll ow
same p r oc edur e w ith os c a t 6 k
Hz , 600 Hz a nd 6 Hz .
LimitsareO . 9 to 1.1.
Switc h osc to 200 k Hz , L im i t s
are . 63 to . 77 volt s a t outpu t .
2 .
Hi g h
P a s s
Ope r a tion
HP ZOO x • I 60 Hz I V
at Outp u t
Meas u re os c volt a g e at fil te r
input. Lim its are 0 .9 to 1. 1 volt s.
Foll ow
sa rn e p r o c ed u re wi th o se at 600 kHz , a nd 60 k Hz , L
'irn it s a re 0 . 9 t o 1. 1
v ol t s . Sw i tc h o s e
to 20 Hz . L i
rri ts are . 63 to . 77 vo lt at o utpu t .
3. Ba nd
P a s s
Op
er a t ion
ZOO x 1 200 x 10
BP 600 Hz I V a t Ou t put
Mea s u r e os c vo l tag e at fil te r input.
Limits are 0 .9 to 1. 1 v olts . Sw it c h
osc
t o 10 0 Hz .
Out put vo lt a g e sho uld be 50 t o 80 m i ll iv ol t s.
Switc h os c
to ZOO Hz . Out put s ho
ul d be .6 3 to . 77 volt. Swit ch os c to 2 kHz ; out-
put sh o uld be • 63 t o • 77 v olt.
Swi t ch osc
to 4 kHz ; ou tput s ho ul d be
50 to 80 millivolt s.
4. Band
Reject
Operation
50 x
100
B R 20 x 10 50 Hz I V at Output
Sw itch os c fr om 50 Hz t o 20 0 Hz ; output s houl d b e . 63 t o . 77 volt. Sw it c h
o s c
to 1 kHz ; outp ut sh o ul d
be le s s tha n 5 mi ll ivolts . Sw it ch os c to 5 k Hz ;
Output s ho ul d be .63 to • 77 volt. Sw itc h o s c illat or to 20 k Hz ,
output
s houl d be 0 .9 to 1. I vo lt s .
5.
Atte n -
ua t
ion
Sl ope (HP )
HP 200 x . 1 50 Hz 1V at Output
Sw it c h os c fr om 50 Hz to 10 Hz . Sw i t c h HP to
20 0 xl a nd os c to 100 Hz .
Sw itc h Hp to ZOO x 10 a nd e sc to I k Hz . Sw it ch HP to 200 x 100 a nd o sc
to 10 k Hz . Output sh ould read be twe en 50 m i ll i volts a nd 80 m i ll iv o lt s at
ea c h H P section mul t ip li e r settin g. Sw
it ch HP to 200 x 100 0 a nd o s c to
100 k Hz , Ou
tput s h ould r e a d 45 mill iv o lt s to 100 rn ill iv ol t s ,
6.
Atten-
ua ti on
Slope(LP) L P
20 x 1000 I kHz I V at Output
Swit ch os c 40 k Hz , Ou
tp ut shoul d r e ad b e twe e n 45 an d 100 mi ll iv o lts .
Sw i tc h L P to 20 x 10 0 and o s c t o 4k Hz .
Swit ch LP to 20 x 10 a nd o s c
to
40 0 Hz .
Sw itc h L P to 20 x I and o s e to 40 Hz . Ou t p ut at ea c h L P m ul -
tiplier setting should be bet w een 50 and 80 m i ll ivolts .
7.
x , I ban d
LP Cali-
b r a tion 1V a t Outpu t
Chang e os c
il l a t or t o 20
Hz .
Read
0 .6 3 to
0.7 7 v ol t at outpu t .
200
x • I 10 Hz
L P
12

----
----
----
- ---
----
----
----
-- --
- - --
Section 3 - In c om i ng Ac c e pta nce an d Inspect ion
T a
ble 3-1 . Accep t ance Che c kout Pro c edu re (Co ntd . ]
In put
Tes t
Func- L P Sec ti on
H P Se
ction
Frequency Set Amplitude
tion
Cuto ff Cu t off
8. x l L P
Calibr a t ion
1V at Output.
Ch an g e os
cillat or to 60 Hz .
Re ad 0.63 to 0 .77 vo lt a t ou tp ut •.
20 Hz
LP 60 x 1
9.
xlO bane
L P Cali -
b r a ti on I V
at Output
Cha ng e os
cill at or to 600 Hz.
Re ad 0 . 6 3
to 0.77 vol t at outpu t.
60 x 10 200 Hz
L P
10 . x i OO
B a nd L P
C
al ib ra ti on 2
kHz I V at ou t put.
Change
o s c ill a to r to 6 k Hz ,
Re ad 0. 63 to 0.77 volt at output.
60 x 100
L P
I
I.
x l OOO
Ba nd
LP
Ca lib r a ti on 20 k
Hz I V at Output
Chan g e o s
ci ll a to r to 60 kHz.
Read O. 8 volt at output .•
60 x 1000
L P
12 . x 10
00
Ba nd HP
Ca
li br at io n 1V at
Outout
Change
o s ci lla t or to 20 k Hz ,
Re ad 0.5 6 to 0.84 volt at
ou t put .
20 x
1000 60 k Hz
HP
13. x l OO
B an d HP
Cal i bra t ion
I V
at Ou t put
Sw itch oscillator to 6 k
Hz ,
Read 0.56
to 0 . 84 vo lt a t ou t put .
20 k Hz
60 x 10 00
H P
14.
x10 HP
Cal ib r atio n HP 6 kHz 1V a t
Output
Change
oscillator to 600 Hz .
Re ad 0.6 3
to 0 .77 v ol t a t: o ut put .
60 x 10
15. x I Ba nd
HP
Cali-
b r a t i on
600 Hz I V at Output
Change
oscillator to 60 Hz .
Read 0.63
to 0 .7 7 v olt a t output .
60 x I
H P
16. x , I
Ban d H P
Ca
li bration H P 1
Vat Output
Cha ng e
oscillat or
to 20
Hz .
Read 0.6 3 to 0 .77 vo lt at ou tp ut.
200 x . I
60 Hz
17.
Max i -
mum
Vo l t -
ag e
200 x 10 00 1 kHz I V a t fi lt e r input
Con ne ct o s c i ll o s co pe to outp ut.
Inc re a s e a m plit ude of os c s ig n al un ti l
clip ping i s ob s erved . Input vo
lt ag e s hould r e ac h 5 vrms be fo r e cl ipp in g
o
ccurs.
20 x 1
BP
18.
Max i-
m un
Cu r -
rent
200 x 1000 I k Hz O. 5 V a t f
il te r Ou t put
Conn
ec t oscill o s c o pe to outp u t. P lace 50 - ohm lo ad a c r o s s
ou t pu t, and
a
dju st ose amp li tu de so tha t ou tp ut is .5 v r m s , No
clipp ing sh o uld oc cu r .
20 x 1
B P
1 ~

Filte r , 3 550
Tabl e 3 -1. A cc e pt a n ce Check ou t Pr oce du r e (C ont d . )
F u n c - H P
Sectio n LP Se c tion
Input
tio n Cuto
ff
T e s t C ut o ff Se t Am p li tud e
Fr eq u enc y
19.
Impe -
dan ce
B P 20 x I
200 x 100 0 2 k Hz O. I V a t
filter
Ou tpu t
S
hu n t out put with 50 hm re si stor . V
olta ge a t output
s h ou ld drop to
•as ± • a1 vo lt .
20 .
Hu m
a nd
Nois e B P 20 x I 200 x 1000
Shiel d fron t a nd r e a r
in p uts . Out pu t vo lt a g e sh ould b e l e s s t ha n ZOO
m i c r ov o lts with 60 Hz l i
ne powe r , an d l e ss t han 50 0 m i c r ov ol t s w i th
400
Hz power .
14

Se cti on 4 - C ir cu it De s c r i tion
SECTION 4
CIRCUIT DESC
RIPTI ON
4.1 GENERAL
Fi gure 4 - 1 s ho ws th e Mod el 35 50 fi lte r in b lo ck d i ag r a m pr e s e nt a ti on .
T he
incomin g signal pa sse s fi rst th r ou gh the unity-gain input amp li f ie r an d the n is
sw i tc hed by th e Functio n Sw it ch eith e r to the High Pas s (HP ) or t he Lo w P a s s (L P)
se c tion or both , depen din g on the fi lt e ri ng function s el e c t e d . In th e Ba nd P a s s
p
os ition bot h s e c ti o ns a r c o nn e c t ed in s e r i e s , In the Band R e j e c t po s i tio n bo th
se c ti on s a r e in paralle l with out p uts added th r oug h a pai r of 10k resist o r s .
Th e output amplifi e r is ca p ac ito r co upl ed, to e li m ina te d c d r ift fro m the pr ev iou s
stage s , and p ro v i de s lo w out p ut im p edance . It al s o ha s v o lt age g ai n to co mpen s a t e
for a dding l o s ses and to maintai n z e r o in sertion l o ss in the Ba nd Rej e c t ( BR) ftlIlC-
tio n ,
T h e f o ll ow ing parag raph s d e s c r i be ea c h section of the Mo de l 3 550 filter more fully.
4.2 INPUT AMPLIFIER
Ea ch of th e I PUT c on ne ct ors , f r on t an d r e a r , ha s a r es i s t o r in s e r i e s . Wit h th e
capacitance of the sh ielded fr ont - t o - rear c a b le the s e r e s i s t o r s a c t a s l ow p a ss
f il te r s , at te n ua ti ng fr eq ue n c i e s ab ove 2 MHz.
The i np ut capa citor C IOI, bl o ck s d c and w ith HIO I prov ide s a l o w fr eque n c y p a s s
ba nd d ow n t o 0 . 2
Hz . Resi stor R I02 pr ote cts the inpu t F E 010 1 ( r om d a m a g e b y
high in pu t v ol tag e s. C I0 2 and R I0 3 a r e hi gh - f req u en c y by pass for R I0 2.
The d rai n 0[ 0 10 1 dr i ve s t he ba s e ofOI02. The c ollector of 010 2, t hr oug h di ssi pa ti on
limitin g r e s is t or R II 0, p r ov i de s the output s ign al, as we ll a s fe e d b ack to the s ou r c e
of 0 10 1. Re s i s to r RI 04, ca pa ci t or C IG3 and t he ferrit e b ead LI OI are fo r loop
stabili zation .
4.3 HIGH PASS SECTION
In pu t t o th e Hi g h Pas s Se ct ion comes fr om the in put l oo p through t he fu n c ti on
s wi
tch. It goes dir e ctly to the firs t HP tun ing ne t wor k con s istin g of two po tenti o -
m
et e rs and tw o c a pa ci to r s. T he po ten tio me te r s a r e ganged , a r e op e r a t ed by
the tunin g d ia l, and hav e s e r ie s and pa rall el tr im m ing r e s i s to r s . The ca pa c it o r s
a r e
sel e c t ed by m ea ns of the ba n d s w it c h . T he va l u e s o f t he tw o net w or k
15

CII
0-
IHIGH PASS SECT IONI
FUNCTION
SWITCH
LP HP
,- --£=
BP
;4 (1 ::4 (; I ~ ~ g ~ > f Jr , I ~ ~ g ;
.#
1° I
1°
02 03
INPUT 1-1_ -
AMPLIFIER I
INPUT
'rJ I
.... .
CIt:.
0-1
c
o-r
I
c:>
J>.
I I
I
tIl
- '
0 rl-
---
~ ~
-e--+- -- +- -~ if'v~ ~ VX f\r"' --i 0 30 1
C1
1° °
'1""
0
.'. I
PJ
Otl
'1
PJ
3
1°
1-
r-
L
I --- 1-
:1
°
I
L- --
-
OUTPUT
AMPLIFIER
030 2
0303
IL 8W1-
I
0306 ~
- I
I
030 4
0 30 5
-
I
I
RESPONSE
SWITCH
I
I
I
IMAX
FLAT .
'rJ
.....
......
....
'1
VJ
V1
V1
o