BRUEL & KJAER 2006 User Manual

Modulation down to 3% (kHz).
Fig. 4.15 shows how to measure modulations down to 3 %. As described in
a previous section (3. Operation) the Heterodyne Voltmeter Type 2006 is
calibrated for measuring modulation (AM or FM) . If the degree of modula-
tion is low the accuracy of the measurement can be improved by connecting
a Microphone Amplifier Type 2603 to the rear connection plug (pin 2 and 4.
4 being ground).
The Microphone Amplifier is calibrated as described in the instruction book
delivered with the instrument, and the knob setting should be:
INPUT SWITCH is set to "Input Potentiometer".
RANGE MULTIPLIER: 0 dB.
METER RANGE: 1 volt full deflection.
With a signal with a relatively high degree of modulation (30-40 % (kHz))
the INPUT POTENTIOMETER of the 2603 should be adjusted, so that the
meter reading (in volts) at the 2603 corresponds to the meter reading of the
2006 (in %/kHz).
Turning the METER RANGE switch on the 2603 one step anticlockwive (100
m V full d~ection) the degree of modulation can now be read from the meter
of the 2603 directly. Full deflection corresponds to a modulation of 10%
(kHz).
If desired the sensitivity of the 2603 can be increased further. It should,
however, not be increased by more than 10 dB (RANGE MULTIPLIER) as the
noise of the amplifiers themselves will then influence the measurements.
Using the Audio Frequency Spectrometer Type 2112 instead of Type 2603 the
noise can be reduced by measuring selectively.
RF- Circuit
--.
!
I
AI
Probe Modulated
RF- Voltage
Plug
0 •
i -= • :_
.• c ~
~. · ~ _";L·~~-~·· 2. .; ·· ··
2103
~6 9o to
Fig. 4.15. Set-up for modulation measurements.
Automatic Recording of Modulation.
When desired the degree of modulation can be recorded automatically. Con-
nect the RECORDER output of the Microphone Amplifier Type 2603 to the
Level Recorder Type 2305 fitted with a linear potentiometer (ZR 0002:
10-110 mV).
The output voltage from the Heterodyne Voltmeter is taken from the rear
connection plug via pins 2 and 4 (pin 4 is grounded).
28

BRUEL & KJAER 2006 Specifications

General

Brand	BRUEL & KJAER
Model	2006
Category	Measuring Instruments
Language	English