Model  3575A
I
Sectiorl I
SECTIO 
N
GENEBA[ 
INFOR
ATION
dBV 
(l 
V rms 
= 
0 
dBV). 
Input levels from 
0.2 mV rms
(" 
74 dBV) to 20 V rms 
(+ 
26 dBV) can 
be 
measured 
with
0.1 dBV resolution 
in two 
voltage  ralges. When 
bg 
B/A is
selected, thc 
panel 
rneter  indicates  the relatiye  amplitude of
the two input 
signals 
in 
dB. The 
display 
range 
for 
relative
measurements 
is 
from 
- 
100 dB to 
+ 
100 
dB with 0.1 dB
resolution. 
Since 
the two input channels 
each 
contain 
ac/dc
corverters and are totally 
indgpendent,  relatiye  measure-
ments 
can 
be made between two signals that 
dilfer 
in
frequency.
1-7. The 3575A 
amplitude 
functions 
are 
particularly 
useful
fbr 
measuring 
gain, 
attenuation 
and other characteristics
where amplitude 
comparison is required. 
The I-og B/A
function eliminates 
the need for 
separate  input and 
output
measurements 
and time conslming 
difference calculations.
1-8. Mlen Phase 
Dsplay is selected, 
the 35754 measures
the 
phase 
difference 
between  two input 
signals. The 
phase
measurement 
range is from 
- 
180 
degrees to 
+ 
180 degrees
with 12 degees 
overrange and 
0.1 
degree 
display reso-
lution. 
Due to 
the wide dynalnic  range of the 
instrumelt,
phase 
difference can 
be measured between  two signals 
that
differ 
in amplitude by 
as 
much 
as 100 dB.
l-9. An accurate 
phase 
meter is of little value 
unless the
accuracy oan 
be maintained 
in the 
presence 
of troise 
and
distortion. 
Udike conventional 
phase 
meters, 
the 3575A
uses 
two 
phase 
detectors rather 
tian a single 
phase
detector. 
This, in conjunction 
with a 
highly 
effective  error
correction 
scheme, 
greatly 
reduces the elfects 
of noise  and
distortion 
on 
phase 
readings.
1-10. 
SPECtFICATT0NS.
l-11. 
Table  l-1 is 
a complete list of 
the Model 
35754
critical 
specifications  that 
are controlled 
by tolerances.
Table 
l-2 contains 
general 
information 
that 
delcribes  the
operatirg 
characteristics  of 
the Model  3575A.
I-12. Any 
changes  ill 
specifications due 
to manufacturing,
design, 
or traceahility 
to the 
U.S. National 
Bureau 
of
Standards 
are 
included  in 
Table 
l-l 
in 
this manual_
Spscficatiols 
listed 
in this manual 
supersede 
all 
previous
specfications  for 
the 
Model  3575A.
1.13.0PTr0NS.
1-1.1. 
There are 
presently 
three 
instrument 
and two acces-
sory options  available 
for the Model 
3575A. 
These options
are as 
follorvs:
I
M
1.1. 
D ESCRTPTT0 
N.
1'1. The Hewlelt-Packard  Model 
1575A 
Gain-Phase  Meter
is a versatile. 
wide-range 
ac voltage 
analyzer 
which affords
diect. convenicnt 
mcasurenent 
of amplitude  and 
phasc
paranletcrs. 
Thc nrajur 
featurcs 
of the instrument  includg
broadband  fiequertcl 
response, wide  dynamic 
range, 
digital
readout 
plus 
a 
unique 
detgction  soheme which ensures
accurate 
phase 
measuremcnts  in 
the 
prescnce 
of noisc 
artd
distortion. These  standard  leatures, along 
with 
a variety  ol
options  including 
dual 
panel 
meters, BCID  output and
remote control. nrake ths 
-3575A 
a truly flexible instrurnent
that 
is well 
suited 
for 
bench 
or 
systems  applications.
l-3. rhc broadbrnd 
liequency 
response  of 
the Model
3575A  extends frorl 
I Hz to l3 Nlllz in 
four 
overlapping
frecluencl'  rartges- For JnaxiJnum 
operating 
corlvenience,
each range  is designed to cover  a wide 
band 
of frequencies
while range seleciability allows the user to optinrize
measuremenl  accuracv 
ar:d scttling tinle 
over 
the 
entire
frequencl 
spe{l.unr.
l-4. The 
-1575A 
is equippcd 
with 
two 
independent input
clunnels. 
Each 
channel 
provides 
an 
lJodB  dynamic range
which allorvs 
"hands ,rff" 
operatioii 
with a wide range of
input 
levels. In 
addition,  each channel  is equipped 
with a
20dB 
input attenurtor rvhich 
provides 
an 
extended 
oper-
ating 
capabiiit)  ol 
100 dB 
in 
two voltage rangcs. Input
sensitivity is fron 
0.] 
mV 
rnrs b  l V mls on the 
lower
range and 
I 
mV nrrs 
to 20 
V 
rins 
on 
the higher  range. The I
Megohm 
( 
30 
pF 
input impedance of each  channel 
permits
the use of l0:l divider 
probes 
which 
further extend 
the
]rl&rinum input level 
to ]00Vrms and the overall  oper-
ating range  to 
I 20 
d B.
l-5. 
The i575A.ontains a 
buiit-in  dc digital 
voltmeter
which 
providcs 
! direcl indication  ol amplitudc  or 
phase 
on
a 3 l/2 digil 
(LLD) 
display. 
Lighted 
annunciators oo the
panel 
rlletcr indicatc dB V, dB or 
degrees  dependinB on 
the
paranreter 
being 
rneasured. 
Thc 
pancl 
nrctcr displa)  is deter-
nlincd b) thc iiont 
panel 
Displa) 
switch 
rvhich 
permits
selection  oi AurplitLrde 
or 
Phase  presentatiorl. 
For recording
purposcs. 
ar1 Analog Output 
(BhvC) 
connector is 
providcd
on the rear 
panel 
ol thc instrument. The Ana)og 
Output
supplies a dc voltage 
proporlional 
to the 
panel 
nteter
reading.
l-6. Wren 
Amplitude  Display  is 
selected, the 
panel 
Ineter
presentation 
is 
controlled 
by the ftont 
panel 
Amplitude
Func'!io11 
switch  which 
permits 
selection 
of 
three different
functiols. 
These 
tunctions 
are Log A, 
Log B and Log ts/A.
When 
Log 
A 
or Log B 
is selected,  the 
panel 
meter 
indicates
the 
logarithrnic 
amplitude  oI 
the respectiye input 
signal 
in
1-l