BRUEL & KJAER 2006 User Manual

inherent noise in the Heterodyne Voltmeter. In Fig. 1.5 is shown typical
curves of sensitivity and Fig. 1.6 shows the inherent noise for the Heterodyne
Voltmeter.
Input voltages around the noise level can be measured by comparison with a
reliable standard signal generator.
A limitation of the measuring range will occur at the lower frequencies of
the input signal for which the corresponding oscillator frequency approaches
the IF and tends to block the IF -amplifier. Consequently, the higher the
frequency is, the lower the level of the measurable input voltage. As indicated
in Fig. 1.5 this limitation is small compared with the frequency range of the
instrument.
Measuring at the IF-Frequency, 11.3 MHz.
The sensitivity of the Heterodyne Voltmeter Type 2006 will change at fre-
quencies just around 11.3 MHz, which is the center frequency of the IF-
amplifier. Depending on the setting of the BANDWIDTH switch it will
increase (Wide) or decrease (Narrow) as shown in Fig. 1.7a. At f = 11.3 MHz
it is
thus only possible to make measurements if the FREQUENCY RANGE
switch is set out of position (between 7 and 1). The oscillator is then dis-
connected, and the frequency response of the Heterodyne Voltmeter will be
as shown in Fig. 1. 7b when the BANDWIDTH switch is set in position
"Wide". As the sensitivity under these circumstances depends on the current
amplification factor of the Mixer transistor, the Heterodyne Voltmeter must
in this case be calibrated specially with a known signal voltage at 10.7 MHz.
Rear Connection J aek.
On the rear plate is a 6-pinned jack to which the following internal connec-
tions are made: Fig. 1.8).
External Battery.
The built-in battery is connected directly to the jack, pins 1 and 5. Therefore
the intenral· 'bTJ.ttery should be removed if an external battery . is connected to
teh terminals. The external battery must have the positive terminal connected
to pin 5.
LF-Output.
The output for external loudspeaker connected directly across the LF-
output should not be loaded with more than 60 Q, and in this case the fre-
quency response is ± 1 dB from 20 Hz to 20ooo Hz. The LF output is found
at pins 2 and 4.
Meter Circuit.
The terminals 3 and 4 can be used for connecting an external meter or ampli-
fier. Pin 4 is connected to the chassis ("ground") and pin 3 is connected to
the meter circuit in series with a 63 kQ resistance.
The Power Supply.
The Heterodyne Voltmeter Type 2006 is designed for battery-operation. The
battery is contained in the instrument and is of the nickel-cadmium storage
8

BRUEL & KJAER 2006 Specifications

General

Brand	BRUEL & KJAER
Model	2006
Category	Measuring Instruments
Language	English