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Measurement Computing DBK Part 2 User Manual

Page 302

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DBK215, pg. 12

897994

DBK Option Cards and Modules

Do not use RC filters in conjunction with additional DBK expansion accessories.

Prior to installing a resistor to the filter network you must drill a 1/16” hole through

the center pinhole [beneath the board’s silkscreen resistor symbol] as indicated in the
preceding figure. Failure to do so will short-circuit the resistor.

Do not drill holes on the board for channels, unless those channels are to receive a

filter network (see preceding statement).

Resistors should be ¼ watt, film-type with up to 5% tolerance. Do not use wire-

wound resistor types.

A resistor value of 510 is recommended. Do not exceed 510 .

Capacitors used are to be of the film dielectric type (e.g., polycarbonate or

NPO ceramic), above 0.001 µF.

RECOMMENDED: For reduction of both Common Mode Noise and Differential

Mode Noise, use one capacitor between Channel High and AGND; and use a second
capacitor between Channel Low and AGND.

For reduction of Differential Noise [when no reduction of Common Mode Noise is

needed] position a capacitor across the respective Channel High and Channel Low.

When in Differential Mode, using capacitors between Channel High, Channel Low,

and AGND may cause a slight degradation of wideband Common Mode rejection.

When making a RC filter network, always install a wire jumper between the relevant

FILT CAP LO and AGND. FILT CAP LO terminals are located on TB9 and TB10.

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