Hewlett-Packard 5890 II Manual

A SERVICE OF

next previous

Signal Output

Zeroing signal output

69

The function of

ZERO

is to subtract a constant background signal from

the detector signal. Background signal sources include the detector itself

(background level depending upon detector type), column bleed, or

contaminants in supply gas(es).

Displaying current

ZERO

setpoint

Current

ZERO

setpoint value is displayed by pressing the appropriate

signal channel key (

SIG 1

or

SIG 2

), followed by

ZERO

(or simply press

ZERO

alone, if the desired signal channel is already displayed). Typical

displays are shown in Figure 5•1.

ACTUAL SETPOINT

SIG 1 ZERO 104.5

ACTUAL SETPOINT

SIG 2 NOT INSTALLED

ACTUAL SETPOINT

ZERO 1 104.5 OFF

ACTUAL SETPOINT

ZERO LIMIT = 83000

Typical Displays

ZERO

Figure 5-1

Table 5•1lists conversions between detector units and the scale used for

ZERO

setpoint values.

FID & NPD 1.0 pA (1.0 10

-12

A)

TCD 25

V (2.5 10

-5

V)

ECD 10 Hz

Detector

Conversion

(1.0 unit = )

ZERO

Table 5-1. Conversions from Detector Units to Setpoint Val-

ues

ZERO