EG&G 113 - Operating Instructions; Introduction; Noise and Source Resistance

7-"
Zq+
L;
Z
“ii
X-=
Z24
M
9N3
:e|nu.u0qaq1
Aq
ua/\q5
sq
L|lp!MpUBq
asqou
1ua|e/\qnba
(sun)
a6e1|0/\
asqou
|eu.uaq1
aomos
. 0L5
Hp
lnduq
‘dune
01
pauaqaq
aelqo/\
asqou
suu
|e1o1
0|
Oz
= amqqq
asq0q\|
(Z)
1
:sau1o:>aq
‘suu:->1
asaql
u|
passaqdxa
amqq
aw’
‘DP
“em
Jaqlo
S!
umas
muanbau
HOHOJ
In
am
4|
asqou
aq_|_
'u|e5
Jaqqqqdwe
9L|l
Aq
Buqpmqqa
Aq
asqou
1ndL'u
"z/M
Aq
paqqdnqnw
Avuanbwq
qqvqqw
:IH
eul
/\|dw!$
S!
suw
'
'
'
'
'
' '
'
'
9H1
4°
Ll1P!/“PUQQ
95!°U
1U9l9'\!"b9
9H1
'(OCI
01
HQIIOJ
;I"l)
paqdnoo
Op
uqleqado
uaq/q/q
'q1pq/v\pueq
Jaqqqqdwe
aq1
10/pue
aql
6uququ.ua1ap
uq
pasn
qlpq/vqpueq
asqou
1ua|e/qqnba
aLq_|_
'
'
'
1ua|e/xqnba
ue
01
pane/\u0o
aq
Aeqw
asqou
1nd1n0
|e1o1
aq_q_
'(o1az aq
01
lnduq
pasnun
a'q1
qoq
qolaaqas
uqqdnoo
aq1
1:-as
‘papua-aquqs
pasn
qq fgqq
qapoq/qq
10;
aouelsqseu
aomos
qeqluaqaqqqp)
swqo
uq
aouelsqsaq
azunos
=
H
sun
s1|0/\
Q3/:||\|
5O||1UB
x
asqou
|BLU.l8L|1
aomos
ZH
U!
LllP!MPUBq
asqou
luaqe/\qnba
=
qv
=
a5e1|o/\
asqou
lnduq
susu
1ua|e/\qnba
qe1o_|_
(3)
5“!"|9>|
U!
amleladwal
amlosqe
=
-L
:(g)
uoqlenba
pue
qdeq
aql
woqq
pauqelqo
aq
ueo
sqqq_|_
‘ls:-ueluq
qo
A1!1uenb
aql Aqqensn
sq
PUB
3
= Su“
asqou
1ndu|
su.u
1ua|e/\qnba
|e1o1
aqa,
‘smoluoo
asaqa,
uqsn
uq
51l°/\
}VHJ.>H7/‘
=
9$!°N
|9U~'19Ll.l_
991"°S
9'41
919W‘/\
>|/saqnoq
8
z_()[
x
331
'1ue1su00
s,uueLuz1q0g
=
>q
(suu)
a6e1|o/\
asqou
|BUJJ8L|1
aomos
x
u|e6
Ol
'
'
60
9“13G°W
3H1
H0’!
8p
1nd1no
Jaqqqqdwe
8L|l
1e
a5e1|0/\
asqou
su.u
|e101
l
Oz
SUn0.|.N00
aunsu
EISION
'|V0ld)\.l.
'l'Ill
@1"5!=l
1H NI
A3N3O3Bi
;OP§
qO|
’O|
{OI
OOI
OI
I
I
OI
2
OI
= aJn6q:q
asq0q\|
(q)
:
amqd
asqo
'
~
ll
N”
F
’
~~
SP0’
aql
paqqeo
sq
sqql
‘sq:-aqqoap
uq
passaqdxa
fasqou
qeuuaqa,
~=P_<v>fmH
azunos
paqqqqdwe
sq),
01
sppe
Jaqqqqdwe
aql
asqou
qo
lunowe
L
s~
8L|1
Aq
paqqqoads
aq
uea
a:>ueuu0,uad
asqou
qaqqqqdwe
‘laadsaq
7
‘W
sqql
uq
'oq1e1
asqou-01-qeuqs
lnduq
aql
Buquqwqz-nap
uq
10102;
=°'p
20*
lueuqwop
aql
sq
aouelsqsaq
aomos
qeuqs
aql
Aq
paleqaua
—+~
8P9
BPQ
,o|/
‘F
“s
voqg,
HBOHHO
—I
BPS
—
I
90!
9 0|
901
s
9990
*
/vxoqq
||q/v\
95B1|0I\
auqq
e
Lqqq
001 woqq
5Ll[1BJ3dQ
'(u0q1e1ad0
WHON
1
i
90
X062V
i—
+
8""
asqou
|BLUJ8L|1
aql
saouelsuq
Auew
uq
'oq1e1
asqou-01-qeuqs
$0,?
W
V, | qqeqa/\o 8L|1
saseaqoap
lseaq
1q
aqaq/v\
suoqlqpuoo
asoql
J9pUl’\
pazqqeaq
aq
01
papqeaq
uz->140
sq
aoueuuoqqad
J9[].!|dUJB
lsag
*~
I
3ONV.LS|SEl!:|
EIOHHOS
CINV
EISION
Z'S
's1uau0du10:)
lqnoqqo
pue
J8LUJO}SUBJ1
J8MOd
amp,
aewep
Aqqqssod
pue
asnq
auqq
3L|1
A
OEZ
1°}
V
Z8/l
1°
U°!1919d°
A
E-ill
1°}
V
9L/L)
Pallelsul
sq
asnq
auqq
azqs
J8dO.ld
sq],
ems
aq
pue
‘pasn
aq
01
a6e1|o/\
10»
saw
~
—
~
qoq
auqq
eql
Buqleoqpuq
uoqlqsod
aq.q1
uq
sq
L|31[N\S
|8UBd-.1881
BM
-*?
1
4L-
89?
I
*
"’—1"'
SP9
' T
so‘
/
avov
P9
oqol
o|O'
aql
ems
a>|ew
'J9MOd
auqq
oe
LUOJ}
Buqleqado
aqoqeg
:3_|_Q|\|
¢
‘
—
'SLUL|O
=|.O
8OUQ1S!S8.l
B
L{5I'\OJl]1
>|OQ[
1nd1n0
aLq1
1e
aqqeqqe/xe
sq
qeuqs
paqqqqdwe
8L|1
!(s)101oauuo:>
‘°‘
em
avo
QPQ
6°‘
1nc|uq
aql
01
paqqdde
sq
paqqqqdwe
aq
01
qeuqs
8L{l
pue
M.
4
‘auqq
oe
aq1
woqq
10
saqqaneq
pauqeluoo-qqas
aql
woqq
Jaqlqa
paqqnbeq
se
paqa/v\0d
sq
luawnnsuq
9L|1
‘A||e1uau1epun:q
'/v\0|aq
passnosqp
aqe
Lqoqq/\/\
qo
qqe
’suoq1
'gqq
qapoq/\|
aq),
10,1
smoluoo
-eqapqsuoo
dooq
punoq
uq
pue
'q.q1pq/vxpueq
aql
6uq1:>a|as
uq
aqnqq
asqou
qo
1as
qeoqd/K1
e
sq
q-|||
a1n6q:q
'/kqqeoqqdeq
'aouepadwq
aamos
qeuqs
8L|1
uqlaaqas
uq
pasqaqaxa
aq
1SLU
pa11o|d
pue
'/kqqeluauqqqadxa
pauqelqo
aqe
samqq
asaq_q_
9199
'8ll
|9P°|N
9H1
W01}
99U9l11J°>l19d
W"W!1d°
Ulelqo
°.L
'aoue1sqsa1
aamos
pue
Aouanbaqq
qo
uoq1aun,q
e se
saqqe/\
qoqq/v\
‘amqq
asqou
oqlsqqalaeqeqo
u/v\0
s1q
seq
Jaqqqqdwe
Lqoeg
|\|()|_|_Q(|()E|_|_|\||
['3
SNOl.I.3H.I.SNl
9NI.l.V!:l3dO
III NOLLOHS
SECTION III
OPERATING INSTRUCTIONS
3.1 INTRODUCTION
To obtain optimum performance from the Model 113, care
must be exercised in selecting the signal source impedance,
in selecting the bandwidth, and in ground loop considera-
tions, all of which are discussed below.
Fundamentally, the instrument is powered as required
either from the self-contained batteries or from the ac line,
and the signal to be ampl ified is applied to the input
connector(s); the amplified signal is available at the output
jack through a resistance of 600 ohms.
NOTE: Before operating from ac line power, make sure the
rear-panel switch is in the position indicating the line
voltage
to be used, and be sure the proper size line fuse is
installed (1/16 A for 115 V operation or 1/32 A for 230 V
operation). Operating from too high a line voltage will blow
the line fuse and possibly damage the power transformer
and circuit components.
3.2 NOISE AND SOURCE RESISTANCE
Best amplifier performance is often regarded to be realized
under those conditions where it least decreases the overall
signal-to-noise ratio. In
many instances the thermal noise
generated by the signal source resistance is the dominant
factor in determining the input signal-to-noise ratio. In this
respect, amplifier noise
performance can be specified by the
amount of noise the amplifier adds to the amplified source
thermal noise; expressed in decibels, this is called the
"Noise Figure":
(1) Noise Figure =
20 I total rms noise voltage at the ampl ifier output
0910 gain x source thermal noise voltage (rms) dB
where the Source Thermal Noise = V4KTRl'lf volts
rms
= E, and
K = Boltzmann's constant, 1.38 x 10-
23
joules/K
T
= absolute temperature in kelvins
M = equivalent noise bandwidth in Hz
R = source resistance in ohms (differential source
resistance for Model 113; if used single-ended, set
the coupling selector for th.e unused input to
ground, and regard this part of input resistance to
be zero).
The total output noise may be converted to an equivalent
input noise by dividing by the amplifier gain. The noise
figure,
expressed in these terms, becomes:
(2) Noise Figure =
20 I total rms noise voltage referred to amp. input dB
0910 source thermal noise voltage (rms)
II 1-1
Each ampl ifier has its own characteristic noise figure, wh ich
varies as a
function of frequency and source resistance.
These figures are
obtained experimentally, and plotted
graphically. Figure 111-1 is a typical set of noise figure
contours for the Model 113.
30dB
--'_---l,
10 -1 10-
1
00
IO~ ~ IO~
FREQUfNr i .N Hz
Figure 111-1. TYPICAL NOISE FIGURE CONTOURS
FOR THE MODEL 113
In using these contours, the total equivalent rms input noise
is usually the quantity of interest. This can be obtained
from the graph and equation (3):
(3)
Total equivalent rms input noise voltage =
source thermal noise x antilog NF/20 volts rms
The equivalent noise bandwidth used in determining the
source thermal noise is a function of the external circuitry
and/or the amplifier bandwidth. When operating dc coupled
(LF rolloff to DC), the equivalent noise bandwidth of the
M113 is simply the HF rolloff frequency multiplied by 1T/2.
If the LF rolloff frequency setting is other than dc, the
equivalent noise bandwidth is given by the formula: