Service manual

8 Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual

Operator’s Check

The operator's check allows the operator to make a quick check of the

instrument prior to use or if a failure is suspected.

Description The attenuator is driven from a 50-ohm signal source at 1 kHz. The output

level from the attenuator is detected by a narrow-bandwidth voltmeter. The

attenuator and detector range switches are stepped together and the

variations in level noted. This veriﬁes that each attenuator section is being

properly switched and checks the low-frequency accuracy of the attenuator.

NOTE The SWR meter used in this check is calibrated for a square-law detector

and therefore the range changes and errors (read in dB) are twice that

indicated by the meter.

Figure 1 Operator Check Setup

Procedure 1. Connect equipment as shown in Figure 1 with the attenuator set to 0 dB.

2. Set the test oscillator to 0.3 Vrms at 1 kHz.

3. Set SWR meter range to 2 dB (expanded) [or for the 8494A/B to 10 dB

(expanded)] and adjust its bandwidth to center of adjustment range. Fine

tune the oscillator frequency to obtain maximum meter indication.

4. Set the attenuator and SWR meter range switch as shown in Table 2 and

verify that SWR meter indicates within limits shown.