Hameg HM 8131-2 Manual page 69

The maximum selectable output voltage in AM
mode is 10.00 V
entered into the keyboard a warning signal will sound,
the former value remains valid. It is not possible to
enter illegal values via the knob or the menu buttons
STOP
With 100 % modulation and 10.00 V
output signal will be 20 V
External source
An external modulation voltage can be connected to the rear
panel terminal AM IN . The waveform can be any. However,
the indication of the modulation depth will be only correct for a
sine wave of 1 kHz and 1.0 V
this case the modulation depth can be set between 0 .. 100 %,
this being equeivalent to internal modulation.
External source: V = 1.4 V
in
HM 8131-2: V = 10 V
o
100 % modulation selected
For 50 % modulation this picture will result:
External source: V = 1.4 V
in
HM 8131-2: V = 10 V
o
50 % modulation selected
Subject to change without notice
. In case a larger value is
pp
selected the total
pp
.
pp
(equal to the internal source). In
rms
, 1 kHz, 1 V/cm
p
, 20 kHz, 5 V/cm,
pp
, 1 kHz, 1 V/cm
p
, 20 kHz, 5 V/cm,
pp
STOP
A further method of varying the modulation depth with
external modulation is by changing the input voltage.
The following example shows the same output signal
as before with an input of ½ = 0.5 V
modulation depth set to 100 %. The amplitude is 0.7 Vp

.
as before. This method is advantageous especially in
automated test systems.
TiPP
External source:
HM 8131-2:
If it is desired to modulate the instrument externally
from 0 to 100 % the amplitude of this signal must
range from 0 to 1.4 Vp, the modulation depth remains set to
100 %. The amplitude may be increased to 3.00 Vp while
simultaneously decreasing the modulation depth setting of
STOP
the instrument. Higher voltages will overmodulate as
demonstrated in the pictures following:
External source:
HM 8131-2:
MainMenu 2 and its functions
Vin = 0.5 V = 0.7 Vp, 1 kHz, 1 V/cm
rms
Vo = 10 V , 20 kHz, 5 V/cm,
pp
100 % modulation selected
Vin = 4.00 Vp, 1 kHz, 2 V/cm
Vo = 10 Vp, 20 kHz, 5 V/cm,
100 % modulation selected
generator overmodulated
and the
rms
69