Table of Contents
Advertisement
;
ensure
that
the
mechanical zero
of
both
meters
is
correctly
set.
Adjustment
is
made
;
•
using
the inset
screw
located centrally
below each meter.
;
(iii)
ensure
that
all
push
buttons
are
in
the
'out'
position
and
that the
supply switch
is in
the
off
positioUi
fif!
(iv)
connect
the
instrument
to the
supply
and
switch
on.
Check
that
the supply indicatinE
lamp
is
illuminated.
The
TF
2337A
is
now
ready
for use,
proceed
as follows
:
2.4.2
Level
Measurement
(i)
Select the
LEVEL
push
button
of
the
FUNCTION
switch.
!
(ii)
Select the
100
V
(40
dB) push button
of the
LEVEL RANGE
switch.
(iii)
Connect
the
signal
to
be
measured
to
the input
terminals.
(iv)
Observe
the
reading on
the
LEVEL
meter.
If
the
reading
is
not within
the 0
dB
to
-10
dB
scale,
continue
to
select
successively
lower
LEVEL
ranges
until
the
desired
indication
is
obtained.
(v)
Note
the
LEVEL
push
button selected.
The
full-scale of the
meter
is
determined by and
indicated
above
this
push
button.
If^measurement
is
required
in
dB's
the signal level
is
determined by
the
sum
of the me*ter indication
and
the
dB
value indicated
(in
RED)
above
the
selected
push
button e.g. with the 30
dB
(30
V) push
button
depressed and
the
meter
reading -5 dB,
the signal level will
be
25
dB
above
1
V.
2.4.3
Distortion
Measurement
_
(i)
Carry
out
Level
measurement
as
described
in
Chapter
2.4.3
(i)
to
(iv).
,
.
(ii)
Select the
desired fundamental
filter
by
selecting either
the
400
Hz
or
1000
Hz
push
button.
.
(iii)
Select the
30%
(-10
dB) push button
of the
DISTORTION
RANGE
switch.
'
'
(iv)
Observe
the
reading on
the distortion
meter.
If
the indication
is
towards
the
-20
dB
end
of the
scale
select
lower
distortion
raises
xmtil
the indication
can be
easily read.
The meter
full-scale
range
is
indicated
by
the
percentage
figure (black)
above
the
press
button selected.
If
measurement
is
required
in
dB's, the distortion
level
is
determined by
adding
the
meter dB
indication (red) to the
dB
figure (red)
immediately above
the
selected
push
button.
i.
e.
if
the -40
dB
push
button
of
the
Distortion
Range
Switch
is
selected
and
the
meter
indi-
cates
-3
dB
then
the distortion
level
measured
is
-43
dB
(0.
7%).
NOTE
t
The
distortion
measurement
is
valid only
if
the
level
meter
indication
lies
between
-10
and
0
on
the
dB
scale.
2.5
CALIBRATION
A
facility for
checking
the distortion
measuring
circuits
is
provided.
Proceed
as follows
TF
2:{37A
Advertisement
Table of Contents
