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2640A/2645A NetDAQ
Users Manual
B-4
Crosstalk from a VAC or frequency signal on a 2640A channel to an adjacent
channel using the slow reading is as shown in Table B-2.
Table B-2. 2640A Crosstalk Specifications
Frequency
VDC 1 kΩ
source
Resistance
100Ω RTD Thermocouple
R <20 kΩ R >20 kΩ
<100 Hz -120 dB .001%/V .01%/V*MΩ .001°/V .001°/V
100 Hz -120 dB .001%/V .05%/V*MΩ .001°/V .003°/V
500 Hz -120 dB .001%/V .05%/V*MΩ .001°/V .01°/V
1 kHz -100 dB .001%/V .05%/V*MΩ .001°/V .01°/V
2 kHz -60 .001%/V .1%/V*MΩ .001°/V .01°/V
2
5 kHz .01 mV/V
2
.005%/V
2
Not recomm. .001°/V
2
.01°/V
2
10 kHz .01 mV/V
2
.005%/V
2
Not recomm. .01°/V
2
.05°/V
2
20 kHz .05 mV/V
2
.01%/V
2
Not recomm. .01°/V
2
Not recomm.
50 kHz .1 mV/V
2
.01%/V
2
Not recomm. .01°/V
2
Not recomm.
100 kHz .1 mV/V
2
.01%/V
2
Not recomm. .01°/V
2
Not recomm.
>500 kHz .1 mV/V
2
.1%/V
2
Not recomm. .01°/V
2
Not recomm.
For frequencies below 5 kHz, the 2640A is roughly 10 times more susceptible to crosstalk at
frequencies that are exact multiples of 300 Hz than it is at the frequencies shown above. e.g., the
sensitivity at 3 kHz will be about 10 times worse than at 2 kHz or 5 kHz.
The above table indicates the amount of crosstalk interference caused by applying VAC to one other
channel. If VAC (or frequency) inputs are applied to multiple channels, multiply the value in the table
by the number of channels with VAC (or frequency) applied.