BRUEL & KJAER 2006 User Manual

As can be seen from the passage below the output voltage of a Signal
Generator depends on the load, and this must be considered when making
a calibration curve. Fig. 4.11 shows a calibration curve made for a Signal
Generator with a 75 [J output impedance. It was measured with the 2006
us in g a 75 .Q te rmin a tion , a nd th e output v olt age s hould thu s ag ree with
the attenuator setting if the attenuator had been exact over the whole range.
Note: The Heterodyne Voltmeter Type 2006 is as mentioned before a
selective voltmeter and therefore it will not give the same deflection as a
diode voltmeter for the same signal if the signal is anything but a pure
sinewave. This is because the diode voltmeter includes the harmonics of the
signal.
Output Impedance.
If the output impedance of the signal generator is unknown it can be
calculated in the following way (see Fig. 4.8).
Probe
Rs
Voltage measured with 2006
without Ra:V=Vt
with Ra: V = Vs
~o~
~ ~ -- - ~ ·- 6 ~- • "': ~ : ~
~ · · .•. ~- ..
Fig. 4..12. Determination of output impedance.
The unloaded voltage (V t) can be measured with the Probe. However, at fre-
quen cies higher than abo ut 150 MHz th e A tt e nu a tor s hould be used du e to the
loading effect of the Probe input impedance. Connecting a load (RB) across
the output of the signal generator will change the reading on the 2006 to VB.
Now it is found that:
RB
VB= Rt + Ha X V t volts
which leads to:
Vt
Rt = RB (VB -1)
25

BRUEL & KJAER 2006 Specifications

General

Brand	BRUEL & KJAER
Model	2006
Category	Measuring Instruments
Language	English